Research ArticleAll-Pass Filter Based Linear Voltage ControlledQuadrature Oscillator

Koushick Mathur1 Palaniandavar Venkateswaran2 and Rabindranath Nandi2

1Department of Electronics amp Communication Engineering UIT Burdwan University West Bengal 713104 India2Department of Electronics amp Telecommunication Engineering Jadavpur University Kolkata 700032 India

Correspondence should be addressed to Rabindranath Nandi robjutelyahoocoin

Received 14 June 2017 Accepted 27 July 2017 Published 29 August 2017

Academic Editor Jiun-Wei Horng

Copyright copy 2017 Koushick Mathur et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A linear voltage controlled quadrature oscillator implemented from a first-order electronically tunable all-pass filter (ETAF) ispresented The active element is commercially available current feedback amplifier (AD844) in conjunction with the relativelynew Multiplication Mode Current Conveyor (MMCC) device Electronic tunability is obtained by the control node voltage (119881)of the MMCC Effects of the device nonidealities namely the parasitic capacitors and the roll-off poles of the port-transfer ratiosof the device are shown to be negligible even though the usable high-frequency ranges are constrained by these imperfectionsSubsequently the filter is looped with an electronically tunable integrator (ETI) to implement the quadrature oscillator (QO)Experimental responses on the voltage tunable phase of the filter and the linear-tuning lawof the quadrature oscillator up to 99MHzat low THD are verified by simulation and hardware tests

1 Introduction

Realization of first-order all-pass filters had been reportedearlier using various types of active building blocks (ABBs)namely VOA [1] Current Conveyor and its variants [2ndash5]DDA [6] DDCC [7] DVCC [8 9] VDIBA [10] and OTAwith differential amplifier [11] as listed in Table 1 some ofthese building blocks are implemented with a basic device(OTA CC or DVCC) combined with some signal (current orvoltage) differential unit Recent literature suggests that elec-tronic function circuits fabricated by commercially availableIC modules are capable of providing desired results [12ndash16]

A varied genre of ABBs emerged during the recent pastfor realizing diverse functions towards signal processingwave formingfiltering applications Fabrication of internaldesign of suchABBs inCMOS technology leads to easy verifi-cation However recent studies address the issues of suchapproach concerning involvement of fabrication cost andcomplexity in their nodal relations with such wide variety ofABBs [12 14 16]

Use of readily available off-the-shelf devices thus maybe an alternate approach to obtaining satisfactory results

Some recent composite blocks yield quite useful results onsignal processing applications wherein two types of basiccommercially available chips are conjoined (eg DDCCDVCC and VDIBA) It has been suggested that compositeblocks may provide better results in comparison to theconstituent elements [17] So for such ABBs requiring morethan one commercially available IC it is still economical andmore convenient compared to chip fabrication [12 16 17]

The relatively newMMCC element [18] used in this workis thus configured using readily available CFA (AD844) andmultiplier (AD835) [19] elements The useful feature of theMMCC is that it has an in-built control voltage terminal (119881)which is conveniently utilized for electronic tuning of a circuitparameter Hence the conventional method of transconduct-ance (119892119898) to bias current (119868119887) conversion is avoided such con-version needs additional hardware complexity and involve-ment of thermal voltage (119881119879) [3 10 16] We now presenthere an electronically tunable all-pass filter (ETAF) using thecomposite CFA-MMCC block

Next a linear voltage controlled quadrature oscillator(LVCQO) is implemented with the ETAF being looped infeedback with an electronically tunable integrator (ETI)

HindawiActive and Passive Electronic ComponentsVolume 2017 Article ID 3454165 8 pageshttpsdoiorg10115520173454165

2 Active and Passive Electronic Components

Table 1 Comprehensive summary of recent APFs

Ref ABB ABB implementation 119891119901 reported (Hz) Tunability[1] VOA HA 2544C opamp 125K 119877119862[2] CCII LF 356N opamp with current mirror 16 K 119877119862[3] DO-CCCII Dual-output current controlled conveyors 163M 119868119887[4] CCC II with OA Current controlled conveyor 1215 K 119868119887[5] DO-CCII CC II with additional z-copy node 389M 119877119862[6] DDA Differential amplifier (DA) 16K 119877119862[7] DDCC Current conveyor with DA 318K 119877119862[8] DVCC VDU followed by OTA 400K 119868119887[9] DVCC VDU followed by CC 159M 119877119862[10] VDIBA OTA with differential input buffer 94M 119868119887[11] OTA OTA with DA 375K 119868119887Proposed CFA-MMCC CFA844 and multiplier AD835 991M 119881Notes (a) Designs in [1 2 10] based on commercially available IC modules (b) comprehensive listing of recent APFs using various ABBs presented in [5]

Detailed analysis is carried out taking into account the deviceimperfections namely parasitic shunt-119903119911119862119911 components andthe roll-off poles of the port-transfer ratios Effects of thesenonidealities are negligible but the higher range of usablefrequencies is constrained The oscillation frequency (120596119900) isactive-insensitive relative to port-mismatch error (120576) Exper-imental results on ETAF and quadrature oscillator responsesare verified by PSPICE simulation and hardware test

2 Analysis

The proposed ETAF is shown in Figure 1(a) where the nodalrelations are as follows

CFA 119868119911 = 120572119868119909 119881119909 = 120573119881119910 and 119881119900 = 120575119881119911MMCC 119868119911 = 119886119868119909 119881119909 = 119887(11989611988111991011198811199102) and 119881119908 = 120574119881119911

The port tracking ratios are ideally unity but may be postu-lated by error coefficients (|120576| ≪ 1) as 120572 = (1 minus 120576119894) = 119886 120573 =(1 minus 120576V) = 119887 and 120575 = (1 minus 120576119911) = 120574 where 119896 equiv (01volt) is themultiplication constant [20]

Analysis of Figure 1(a) yields the transfer function 119866 equiv119881119900119881119894 as119866 = 12057511205752119898 + (12057511205752 minus 1) 12057221205732 119904119899120591 minus 1205721120572212057511205752119886119887120574[119904119899120591 + 12057211205751119886119887120574] (1)

parasitic elements yielding a modified transfer where 119898 =11990331199034 119899 = 11990321199031 and 120591 = 119877119862119896119881In ideal devices port tracking ratios are all unity assum-

ing the realizability conditions as 119898 = 1 = 119899 (1199031234 = 119903) forsimplicity we get

119866 = (119904120591 minus 1)(119904120591 + 1) (2)

which is the nonminimum phase all-pass function wheretransmission gain |119866| = 1 and phase (120579) is tunable in a range180 le 120579∘ le 0 being variable by control voltage (119881) as

120579 = 120587 minus 2 arctan(120596119877119862119896119881 ) (3)

3 Effects of Nonidealities

31 Parasitic Components The parasitic components appearas shunt-119903119911119862119911 arms at current source nodes of the device asper data-book [21] the typical values are 2 le 119903119911 (MΩ) le5 and 3 le 119862119911 (pF) le 55 ratio of circuit resistors (KΩ)relative to 119903119911 is assumed to be negligible Reanalysis now withfinite parasitic elements yields modified transfer elements inFigure 1(a) exhibiting a single-pole roll-off model [22] givenby

119866 = (11989921199042 + 1198991119904 + 119899119900 minus 1)(11988931199043 + 11988921199042 + 1198891119904 + 119889119900 + 1) (4)

where

1198992 = 1205911205911199111 (1 + 120590)1198991 = 120591 (1 + 120590) (1 + 1205831) + (12058331205911199111)119899119900 = 1205833 (1 + 1205831)1198893 = 12059112059111991111205911199112 (1 + 120590)1198892 = 1205911205911199111 (1 + 120590) (1 + 1205832)

+ 1205911205911199112 (1 + 120590) (1 + 1205831) + (120583312059111991111205911199112)1198891 = 120591 (1 + 120590) (1 + 1205831) + (12058331205911199111) (1 + 1205832)

+ 12059111991121205833 (1 + 1205831)119889119900 = 1205832120590 = 1198621199113119862 ≪ 1

12058312 = 11990311990311991112 ≪ 1

Active and Passive Electronic Components 3

+

Eo

Vo

y1

y2

rz3 Cz3 Co

Cz1

Cz2

rz1

rz2

r2

r1 r3

r4

Vi

x

y

zx

y z

k

V

x

w

z

R

ECFA 1

CFA 2

MMCC

(a)

+

AD844

AD835

k

X

Z

w

minus

y1

y2

(b)

Figure 1 (a) First-order ETAF (b) Implementation of MMCC with commercially available ICs

1205833 = 119877119896V1199031199113 ≪ 1

12059111991112 = 1199031198621199111212059111991112120591 ≪ 1

(5)

Then (4) simplifies to

119866 = [11990421205911205911199111 + 119904120591 minus 1][119904312059112059111991111205911199112 + 1199042 (1205911199111 + 1205911199112) + 119904120591 + 1] (6)

The frequency-domain behavior may be estimated bywriting 119904 = 119895120596 in (6) given by

119866 (120596) = [119895120596120591 minus (1 + 1205771)][119895 120596120591 (1 minus 1205772) + (1ndash1205773)] (7)

where

1205771 = 12059621205961199011205961199111 ≪ 1

120596119901 (filter-pole frequency) = 1120591 1205961199111 =

11205911199111

1205772 = 120596212059611991121205961199111 ≪ 1

1205773 = 1205962120591 (1205911199111 + 1205911199112)100381610038161003816100381610038161205911199111=1205911199112=120591119911 asymp 21205962120591120591119911 asymp 21205962120596119901120596119911 ≪ 1

(8)

With119862119911 asymp 33 pF (measured) and 119903 = 1KΩ we estimatedvalue of the parasitic pole frequency 119891119911 asymp 54MHz Hencefor usable ranges of lt 119891119911 effects of parasitic capacitors arenegligible and 119866 = 119866 therefore the nominal APF function ispreserved with the limit 119891 le 119891119911

32 Roll-Off Pole of Device-Port Transfer Ratios At relativelyhigh-frequency ranges the port-transfer ratios 120572 120573 120575 and 119886119887 120574 of the active components are as follows

12057212 = 12057211990012(11990411990112 + 1)12057512 = 12057511990012(11990411990134 + 1)1205732 = 1205731199002(1199041199015 + 1)119886 = 119886119900(119904119901119894 + 1)119887 = 119887119900(119904119901V + 1)120574 = 120574119900(119904119901119911 + 1)

(9)

The dc values of all the products of port coefficients in (1)may be taken as unity for example 12057211990012 asymp 1minus(1205761198941+1205761198942) asymp 1since 12057611989412 ≪ 1

The modified APF function (1198661015840) is now written as

1198661015840 = [Δ 1 + Δ 2 (Δ 1ndash1) 119904120591 minus Δ 3119872][119904120591 + Δ 4119872(119904)] (10)

where

Δ 1 = 12057511205752 asymp 1119904211990131199014 + 119904 (1199013 + 1199014) + 1 (11)

Δ 2 = 12057221205732 asymp 1119904211990111199015 + 119904 (1199011 + 1199015) + 1 (12)

Δ 3 = 12057211205722 asymp 1119904211990111199012 + 119904 (1199011 + 1199012) + 1 (13)

Δ 4 = 12057211205751 asymp 1119904211990111199013 + 119904 (1199011 + 1199013) + 1 (14)

4 Active and Passive Electronic Components

Table 2 Comparative description of recent QO designs

Ref Device used Electronic tunability Linear tuning law 119891119900 reported (Hz) Tuning by THD ()[5] DO-CCII No No 233M 119877119862 117sim282[10] VDIBA Yes No 85M radic119868119887 225[12] CFA No No 909K 119877119862 mdash[14] CFA No No 398K 119877119862 142[23] OTA Yes Yes 64K 119868119887 mdash[24] VOA No No 160K 119877119862 mdash[25] CFOA No No 159K 119877119862 316[26] CDTA Yes No 173M radic119868119887 30[27] CCCDBA Yes No 419K radic119868119887 2sim12[28] CCCCTA Yes No 11M radic119892119898 1sim29[29] OTA Yes No 159M radic119892119898 1sim22Proposed CFA-MMCC Yes Yes sim102M 119881 09 sim28

The function119872(119904) relates to the MMCC block it is decom-posed as119872(119904) = 119872119900(119904) sdot 119872119890(119904) where119872119900 = 1119904120591119900 and

119872119890 (119904) = 1[(119904119901119894 + 1) (119904119901V + 1) (119904119901119911 + 1)] (15)

It has been observed that the 3 dB corner frequenciesfor all the port-transfer ratios appear at close proximity andhence these may be assumed equal without loss of generality[22] Therefore calculations for examining the effects of theroll-off poles become simpler if wewrite1199011sim5 equiv 1120596119901Writing119906 = (120596120596119901) ≪ 1 and solving for (11) we get

Δ 1 (119895120596) = 11 minus 1199062 + 2119895119906 (16)

which implies |Δ 1| = radic(1+41199062) asymp 1 and NΔ 1 = arctan(2119906) asymp0 Similar results are checked for (12) to (14) For the effects ofthe MMCC roll-off we put 120595 = (120596120596119898) ≪ 1 where 119901119894V119911 equiv1120596119898 solving (15) we get

119872119890 (119895120596) = 1[(1 minus 31205952) + 1198953120595 1 minus (12059523)] (17)

which reduces to |119872119890| = 1 and N119872119890 = minus arctan(3120595) asymp 0This analysis indicates that effects of roll-off poles of the activebuilding blocks are quite negligible in the range of operatingfrequencies (119891 lt 119891119901119898)4 LVCQO Implementation

Quadrature oscillators find diverse application in mea-surement systems [30ndash33] and in communication circuitsquadrature mixers SSB-modulator vector generator anddata conversion A comprehensive summary of recent QOdesigns is listed in Table 2 It may be seen that even thougha number of such oscillators were reported very few arelinearly tunable

We now present the linear VCO as implemented byforming a regenerative feedback loop formed with the ETAFin Figure 1(a) and the ETI in Figure 2 transfer of ETI is

119867(119904) = 1119904120591119900 (1 + 120585) + (119877119900119903119911) (18)

MMCC

k

V

x

w

z

Vi y1

y2 +

Vo

CzCo rzRo

Figure 2 Electronically tunable integrator (ETI)

where 120591119900 = 119877119900119862119900119896119881 120585 = 119862119900119862119911 ≪ 1 and 119877119900119903119911 ≪1 hence 119867(119904) = 1119904120591119900 Grounding of the capacitor (119862)facilitates absorbing119862119911 in119862-values at predesign level Deviceimperfection relative to port-transfer roll-off pole frequencies(120596119886119887120574) is estimated by writing

119867(119904) = (119886119887120574)119904120591119900 equiv (1 minus 120576119879)(119904120591119900) (19)

where 120576119879 = (120576119894 + 120576V + 120576119911) ≪ 1The deviation due to roll-off is

= ( 119904120596119886) + 1(

119904120596119887) + 1(

119904120596120574) + 1 (20)

As in previous section if we assume 120596119886119887120574 asymp 120596119898 and put 120595 =(120596120596119898) then reduces similar to (17) as

| = 1N = minus arctan (3120595) asymp 0 (21)

Active and Passive Electronic Components 5

020406080

100120140160180

(A)(B)

Frequency (Hz)

0

6

(dB)

20M10M1M500k

(B) (6 MHz V = 6

(A) (9 MHz V = 9 vＩＦＮs)

minus6

∘

e | fp (－（Ｔ)

(A) 31∘ Ｎ fp = 90

(B) 12∘ Ｎ fp = 60

vＩＦＮs)

(a)

02 04 06 08 1001

025

05

075

1

THD

()

Vip (volt)

9MHz6 Mhz

(b)

Time (sec)0

Am

plitu

de (v

olt)

00

75

minus75

500n250n

(c)

(d)

1 4 7 100

Simulation

Freq

uenc

y (H

z)

10M

5M

V (dc volt)

Hardware (C = 40 Ｊ R = 400Ω)Hardware (C = 80 Ｊ R = 400Ω)

(e)

Figure 3 Continued

6 Active and Passive Electronic Components

Quadrature phase error THD

2 066 1610 28

080 085 090 095 100 105 110 115 120

01020304050

Gain-crossover point

0

(C)

(B)

Gai

n (d

B)

(A)minus10

minus20

minus30

minus40

minus50

(C) (8 MHz)(B) (4 MHz)(A) (1－Ｔ)

fo (－（Ｔ)(Δ)

12∘

24∘

31∘

∘

u = (ffo)

(f)

Figure 3 Measured response of ETAF and QO (a) AP phase response (A) = 9Vdc (B) = 6Vdc (b) AP-THD () to 7th harmonic (c)QO wave response tuned at 10MHz quadrature signals at 119881119900 and 119864119900 nodes (d) QO spectral response of 10MHz for phase-noise evaluation(e) QO linear-tuning response (f) Measured tuning error of VCO

Now implementation of oscillator is derived by equating 1 minus119866119867(119904) equiv 0 which gives the characteristic equation (CE)

CE 1199042120591119900120591 + 119904 (120591119900 minus 120591) + 1 = 0Realizability condition 120591119900 = 120591

119877 = 119877119900119862 = 119862119900

Oscillation frequency 120596119900 = 119896119881119877119862

(22)

So tuned frequency (119891119900 in Hz) is linearly and directlyvariable by control voltage (119881)

119891119900 = 119881(20120587119877119862) (23)

The proposed method provides direct electronic tunabil-ity of oscillation frequency by the control voltage (119881) Noadditional current processing circuitry for 119892119898 to bias current(119868119887) conversion is needed as seen in the previous designsshown in Table 1 and thermal voltage (119881119879) is not involvedIt may be seen that 120596119900 is practically active-insensitive 119878120576120596119900 asymp05120576 ≪ 15 Experimental Results

The response of 119881-tunability of the proposed ETAF andLVCQO had been verified by PSPICE simulation [34] andhardware tests these are shown in Figure 3 ETAF responsesalong with its phase error (120579119890) and THD (measured to 7thharmonic) are shown in Figures 3(a) and 3(b) which arerelatively low compared to [10 24 25] Some small phaseerror (120579119890) on the experimentally generated sinusoid quadra-ture signals deviated around 90∘ was measured as shown in

Figure 3(c) The oscillator spectral response in Figure 3(d)shows the LVCQO spectral response wherein phase noisemeasured is minus107 dBcHz at an offset of 100KHz from thetuned frequency of 10MHz this response is measured byTektronix spectrum analyzer (RSA306B) [35]

This result is better as compared to that in [14] Anew method of examining the VCO tuning error (120573) isadopted by measuring the shift (Δ119891) in 119891119900 at phase cross-overfrequency The tested value of 120573 in the overall tuning rangeof 1MHzsim10MHz was observed to be less than 45

6 Conclusion

A new design of ETAF function and its subsequent applica-tion to the implementation of aVCQOwith linear-tuning laware presented The active blocks are commercially availableCFA (AD844) and four-quadrant multiplier (AD835) whichare readily available IC modules Responses of the functioncircuits are verified experimentally with PSPICE simulationand hardware testsThe quadrature oscillator had been tunedby control voltage (119881) in a linear range (band-spread) of05 le 119891119900 (MHZ) le 99 at low THD The design does notneed any additional current processing circuitry hence thereis no extra quiescent dissipation Power dissipation of theproposed oscillator circuit is about 33mW The circuit ispractically active-insensitive relative to device-port track-error (120576) Analysis on the effects of device parasitic com-ponents indicates insignificant effect on design equationseven though parasitic capacitors tend to limit the usablehigh-frequency range In this work a relatively new buildingblock namely the MMCC had been utilized for the voltage(119881) controlled linearly tunable quadrature oscilator designwith 107 dBcHz phase noise at 100KHz offset as shown inFigure 3(d) Thus a comparatively better quality result hadbeen obtained as is shown in Table 2

Active and Passive Electronic Components 7

It may be seen in Tables 1 and 2 that in the cited designsactive devices used are certain primary blocks with auxiliaryvoltagecurrent differencing unit (VDUCDU) or differentialamplifiers with their associated parasitics which tend to limitthe desired range of frequency (119891119901 or 119891119900) [6] Also tuningby 119892119898 or 119868119887 needs additional current processing circuitswith parasitic capacitors The authors believe that owing tosuch topological distinction the frequency tuning ranges aresomewhat lower However in the case of design by VDIBA[10] the range improves owing to the fact that the active com-ponent OPA-860 has itself a bandwidth (BW) of 470MHzIn the proposed design no such VDUCDU and 119892119898-to-119868119887conversion circuitry are used this circuit is structured withcommercially available AD844 (BW = 60MHz) and AD835(250MHz) ICmodules to achieve relatively higher frequencywherein effects of port-mismatch roll-off poles and parasiticshad been included in support

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] S J G Gift ldquoApplication of all-pass filters in the design ofmultiphase sinusoidal systemsrdquoMicroelectronics Journal vol 31no 1 pp 9ndash13 2000

[2] M Higashimura and Y Fukui ldquoRealization of current mode all-pass networks using a current conveyorrdquo IEEE Transactions onCircuits and Systems vol 37 no 5 pp 660-661 1990

[3] S Oztayfun S Kilinc A Celebi and U Cam ldquoA new elec-tronically tunable phase shifter employing current-controlledcurrent conveyorsrdquo International Journal of Electronics andCommunications vol 62 no 3 pp 228ndash231 2008

[4] S Minaei and O Cicekoglu ldquoA Resistorless realization of thefirst-order all-pass filterrdquo International Journal of Electronicsvol 93 no 3 pp 177ndash183 2006

[5] F Yucel and E Yuce ldquoCCII based more tunable voltage-modeall-pass filters and their quadrature oscillator applicationsrdquoInternational Journal of Electronics and Communications vol68 no 1 pp 1ndash9 2014

[6] A Toker and S Ozoguz ldquoNovel all-pass filter section usingdifferential difference amplifierrdquo International Journal of Elec-tronics and Communications vol 58 no 2 pp 153ndash155 2004

[7] J-W Horng C-M Wu and N Herencsar ldquoFully differentialfirst-order allpass filters using a DDCCrdquo Indian Journal ofEngineering and Materials Sciences vol 21 no 4 pp 345ndash3502014

[8] T Tsukutani H Tsunetsugu Y Sumi andN Yabuki ldquoElectron-ically tunable first-order all-pass circuit employing DVCC andOTArdquo International Journal of Electronics vol 97 no 3 pp 285ndash293 2010

[9] M A Ibrahim S Minaei and E Yuce ldquoAll-pass sections withrich cascadability and IC realization suitabilityrdquo InternationalJournal of CircuitTheory andApplications vol 40 no 5 pp 461ndash472 2012

[10] N Herencsar S Minaei J Koton E Yuce and K Vrba ldquoNewresistorless and electronically tunable realization of dual-outputVM all-pass filter using VDIBArdquo Analog Integrated Circuits andSignal Processing vol 74 no 1 pp 141ndash154 2013

[11] A U Keskin K Pal and E Hancioglu ldquoResistorless first-orderall-pass filter with electronic tuningrdquo International Journal ofElectronics and Communications vol 62 no 4 pp 304ndash3062008

[12] S Maheshwari and M S Ansari ldquoCatalog of realizationsfor dxccii using commercially available ics and applicationsrdquoRadioengineering vol 21 no 1 pp 281ndash289 2012

[13] S J G Gift and BMaundy ldquoAn improvedmultiphase sinusoidaloscillator using current feedback amplifierrdquo International Jour-nal of Electronics vol 4 pp 177ndash187 2016

[14] H-P Chen Y-S Hwang Y-T Ku S-F Wang and C-HWu ldquoVoltage-mode universal biquadratic filter and quadratureoscillator using CFAsrdquo IEICE Electronics Express vol 13 no 15pp 1ndash11 2016

[15] R Sotner J Jerabek N Herencsar J-W Horng K Vrba and TDostal ldquoSimple oscillator with enlarged tunability range basedon ECCII and VGA utilizing commercially available analogmultiplierrdquo Measurement Science Review vol 16 no 2 pp 35ndash41 2016

[16] S Siripongdee and W Jaikla ldquoElectronically controllablegrounded inductance simulators using single commerciallyavailable IC LT1228rdquo International Journal of Electronics andCommunications vol 76 pp 1ndash10 2017

[17] S J G Gift and B Maundy ldquoVersatile composite amplifierconfigurationrdquo International Journal of Electronics vol 102 no6 pp 993ndash1006 2014

[18] Y-S HwangW-H Liu S-H Tu and J-J Chen ldquoNew buildingblock multiplication-mode current conveyorrdquo IET CircuitsDevices and Systems vol 3 no 1 pp 41ndash48 2009

[19] ldquoAnalog Devices AD-835 250 MHz voltage output four quad-rantmultiplierrdquo httpwwwanalogcomdatasheetsAD835pdf

[20] ldquoIntersil datasheet file 24775 Sept 1998 28634 Apr 1999rdquo[21] ldquoAnalog devices Linear products data-book (MA USA)rdquo 1990[22] E Yuce and SMinaei ldquoAmodifiedCFOA and its applications to

simulated inductors capacitancemultipliers and analog filtersrdquoIEEE Transactions on Circuits and Systems vol 55 no 1 pp266ndash275 2008

[23] K Kumwachara and W Surakampontorn ldquoAn integrabletemperature-insensitive gm-RC quadrature oscillatorrdquo Interna-tional Journal of Electronics vol 90 no 9 pp 599ndash605 2003

[24] J-W Horng ldquoQuadrature oscillators using operational ampli-fiersrdquoActive and Passive Electronic Component vol 2011 ArticleID 320367 4 pages 2011

[25] A LahiriW Jaikla andM Siripruchyanun ldquoFirst CFOA-basedexplicit-current-output quadrature sinusoidal oscillators usinggrounded capacitorsrdquo International Journal of Electronics vol100 no 2 pp 259ndash273 2013

[26] J Jin and CWang ldquoSingle CDTA-based current-mode quadra-ture oscillatorrdquo International Journal of Electronics and Commu-nications vol 66 no 11 pp 933ndash936 2012

[27] F Khateb W Jaikla D Kubanek and N Khatib ldquoElectronicallytunable voltage-mode quadrature oscillator based on highperformance CCCDBArdquo Analog Integrated Circuits and SignalProcessing vol 74 no 3 pp 499ndash505 2013

[28] W Sa-Ngiamvibool and A Jantakun ldquoQuadrature oscillatorusing CCCCTAs and grounded capacitors with amplitudecontrollabilityrdquo International Journal of Electronics vol 101 no12 pp 1737ndash1758 2014

[29] N Pandey and R Pandey ldquoApproach for third order quadratureoscillator realisationrdquo IET Circuits Devices and Systems vol 9no 3 pp 161ndash171 2015

Active and Passive Electronic Components 3

+

Eo

Vo

y1

y2

rz3 Cz3 Co

Cz1

Cz2

rz1

rz2

r2

r1 r3

r4

Vi

x

y

zx

y z

k

V

x

w

z

R

ECFA 1

CFA 2

MMCC

(a)

+

AD844

AD835

k

X

Z

w

minus

y1

y2

(b)

Figure 1 (a) First-order ETAF (b) Implementation of MMCC with commercially available ICs

1205833 = 119877119896V1199031199113 ≪ 1

12059111991112 = 1199031198621199111212059111991112120591 ≪ 1

(5)

Then (4) simplifies to

119866 = [11990421205911205911199111 + 119904120591 minus 1][119904312059112059111991111205911199112 + 1199042 (1205911199111 + 1205911199112) + 119904120591 + 1] (6)

The frequency-domain behavior may be estimated bywriting 119904 = 119895120596 in (6) given by

119866 (120596) = [119895120596120591 minus (1 + 1205771)][119895 120596120591 (1 minus 1205772) + (1ndash1205773)] (7)

where

1205771 = 12059621205961199011205961199111 ≪ 1

120596119901 (filter-pole frequency) = 1120591 1205961199111 =

11205911199111

1205772 = 120596212059611991121205961199111 ≪ 1

1205773 = 1205962120591 (1205911199111 + 1205911199112)100381610038161003816100381610038161205911199111=1205911199112=120591119911 asymp 21205962120591120591119911 asymp 21205962120596119901120596119911 ≪ 1

(8)

With119862119911 asymp 33 pF (measured) and 119903 = 1KΩ we estimatedvalue of the parasitic pole frequency 119891119911 asymp 54MHz Hencefor usable ranges of lt 119891119911 effects of parasitic capacitors arenegligible and 119866 = 119866 therefore the nominal APF function ispreserved with the limit 119891 le 119891119911

32 Roll-Off Pole of Device-Port Transfer Ratios At relativelyhigh-frequency ranges the port-transfer ratios 120572 120573 120575 and 119886119887 120574 of the active components are as follows

12057212 = 12057211990012(11990411990112 + 1)12057512 = 12057511990012(11990411990134 + 1)1205732 = 1205731199002(1199041199015 + 1)119886 = 119886119900(119904119901119894 + 1)119887 = 119887119900(119904119901V + 1)120574 = 120574119900(119904119901119911 + 1)

(9)

The dc values of all the products of port coefficients in (1)may be taken as unity for example 12057211990012 asymp 1minus(1205761198941+1205761198942) asymp 1since 12057611989412 ≪ 1

The modified APF function (1198661015840) is now written as

1198661015840 = [Δ 1 + Δ 2 (Δ 1ndash1) 119904120591 minus Δ 3119872][119904120591 + Δ 4119872(119904)] (10)

where

Δ 1 = 12057511205752 asymp 1119904211990131199014 + 119904 (1199013 + 1199014) + 1 (11)

Δ 2 = 12057221205732 asymp 1119904211990111199015 + 119904 (1199011 + 1199015) + 1 (12)

Δ 3 = 12057211205722 asymp 1119904211990111199012 + 119904 (1199011 + 1199012) + 1 (13)

Δ 4 = 12057211205751 asymp 1119904211990111199013 + 119904 (1199011 + 1199013) + 1 (14)

4 Active and Passive Electronic Components

Table 2 Comparative description of recent QO designs

Ref Device used Electronic tunability Linear tuning law 119891119900 reported (Hz) Tuning by THD ()[5] DO-CCII No No 233M 119877119862 117sim282[10] VDIBA Yes No 85M radic119868119887 225[12] CFA No No 909K 119877119862 mdash[14] CFA No No 398K 119877119862 142[23] OTA Yes Yes 64K 119868119887 mdash[24] VOA No No 160K 119877119862 mdash[25] CFOA No No 159K 119877119862 316[26] CDTA Yes No 173M radic119868119887 30[27] CCCDBA Yes No 419K radic119868119887 2sim12[28] CCCCTA Yes No 11M radic119892119898 1sim29[29] OTA Yes No 159M radic119892119898 1sim22Proposed CFA-MMCC Yes Yes sim102M 119881 09 sim28

The function119872(119904) relates to the MMCC block it is decom-posed as119872(119904) = 119872119900(119904) sdot 119872119890(119904) where119872119900 = 1119904120591119900 and

119872119890 (119904) = 1[(119904119901119894 + 1) (119904119901V + 1) (119904119901119911 + 1)] (15)

It has been observed that the 3 dB corner frequenciesfor all the port-transfer ratios appear at close proximity andhence these may be assumed equal without loss of generality[22] Therefore calculations for examining the effects of theroll-off poles become simpler if wewrite1199011sim5 equiv 1120596119901Writing119906 = (120596120596119901) ≪ 1 and solving for (11) we get

Δ 1 (119895120596) = 11 minus 1199062 + 2119895119906 (16)

which implies |Δ 1| = radic(1+41199062) asymp 1 and NΔ 1 = arctan(2119906) asymp0 Similar results are checked for (12) to (14) For the effects ofthe MMCC roll-off we put 120595 = (120596120596119898) ≪ 1 where 119901119894V119911 equiv1120596119898 solving (15) we get

119872119890 (119895120596) = 1[(1 minus 31205952) + 1198953120595 1 minus (12059523)] (17)

which reduces to |119872119890| = 1 and N119872119890 = minus arctan(3120595) asymp 0This analysis indicates that effects of roll-off poles of the activebuilding blocks are quite negligible in the range of operatingfrequencies (119891 lt 119891119901119898)4 LVCQO Implementation

Quadrature oscillators find diverse application in mea-surement systems [30ndash33] and in communication circuitsquadrature mixers SSB-modulator vector generator anddata conversion A comprehensive summary of recent QOdesigns is listed in Table 2 It may be seen that even thougha number of such oscillators were reported very few arelinearly tunable

We now present the linear VCO as implemented byforming a regenerative feedback loop formed with the ETAFin Figure 1(a) and the ETI in Figure 2 transfer of ETI is

119867(119904) = 1119904120591119900 (1 + 120585) + (119877119900119903119911) (18)

MMCC

k

V

x

w

z

Vi y1

y2 +

Vo

CzCo rzRo

Figure 2 Electronically tunable integrator (ETI)

where 120591119900 = 119877119900119862119900119896119881 120585 = 119862119900119862119911 ≪ 1 and 119877119900119903119911 ≪1 hence 119867(119904) = 1119904120591119900 Grounding of the capacitor (119862)facilitates absorbing119862119911 in119862-values at predesign level Deviceimperfection relative to port-transfer roll-off pole frequencies(120596119886119887120574) is estimated by writing

119867(119904) = (119886119887120574)119904120591119900 equiv (1 minus 120576119879)(119904120591119900) (19)

where 120576119879 = (120576119894 + 120576V + 120576119911) ≪ 1The deviation due to roll-off is

= ( 119904120596119886) + 1(

119904120596119887) + 1(

119904120596120574) + 1 (20)

As in previous section if we assume 120596119886119887120574 asymp 120596119898 and put 120595 =(120596120596119898) then reduces similar to (17) as

| = 1N = minus arctan (3120595) asymp 0 (21)

Active and Passive Electronic Components 5

020406080

100120140160180

(A)(B)

Frequency (Hz)

0

6

(dB)

20M10M1M500k

(B) (6 MHz V = 6

(A) (9 MHz V = 9 vＩＦＮs)

minus6

∘

e | fp (－（Ｔ)

(A) 31∘ Ｎ fp = 90

(B) 12∘ Ｎ fp = 60

vＩＦＮs)

(a)

02 04 06 08 1001

025

05

075

1

THD

()

Vip (volt)

9MHz6 Mhz

(b)

Time (sec)0

Am

plitu

de (v

olt)

00

75

minus75

500n250n

(c)

(d)

1 4 7 100

Simulation

Freq

uenc

y (H

z)

10M

5M

V (dc volt)

Hardware (C = 40 Ｊ R = 400Ω)Hardware (C = 80 Ｊ R = 400Ω)

(e)

Figure 3 Continued

6 Active and Passive Electronic Components

Quadrature phase error THD

2 066 1610 28

080 085 090 095 100 105 110 115 120

01020304050

Gain-crossover point

0

(C)

(B)

Gai

n (d

B)

(A)minus10

minus20

minus30

minus40

minus50

(C) (8 MHz)(B) (4 MHz)(A) (1－Ｔ)

fo (－（Ｔ)(Δ)

12∘

24∘

31∘

∘

u = (ffo)

(f)

Figure 3 Measured response of ETAF and QO (a) AP phase response (A) = 9Vdc (B) = 6Vdc (b) AP-THD () to 7th harmonic (c)QO wave response tuned at 10MHz quadrature signals at 119881119900 and 119864119900 nodes (d) QO spectral response of 10MHz for phase-noise evaluation(e) QO linear-tuning response (f) Measured tuning error of VCO

Now implementation of oscillator is derived by equating 1 minus119866119867(119904) equiv 0 which gives the characteristic equation (CE)

CE 1199042120591119900120591 + 119904 (120591119900 minus 120591) + 1 = 0Realizability condition 120591119900 = 120591

119877 = 119877119900119862 = 119862119900

Oscillation frequency 120596119900 = 119896119881119877119862

(22)

So tuned frequency (119891119900 in Hz) is linearly and directlyvariable by control voltage (119881)

119891119900 = 119881(20120587119877119862) (23)

The proposed method provides direct electronic tunabil-ity of oscillation frequency by the control voltage (119881) Noadditional current processing circuitry for 119892119898 to bias current(119868119887) conversion is needed as seen in the previous designsshown in Table 1 and thermal voltage (119881119879) is not involvedIt may be seen that 120596119900 is practically active-insensitive 119878120576120596119900 asymp05120576 ≪ 15 Experimental Results

The response of 119881-tunability of the proposed ETAF andLVCQO had been verified by PSPICE simulation [34] andhardware tests these are shown in Figure 3 ETAF responsesalong with its phase error (120579119890) and THD (measured to 7thharmonic) are shown in Figures 3(a) and 3(b) which arerelatively low compared to [10 24 25] Some small phaseerror (120579119890) on the experimentally generated sinusoid quadra-ture signals deviated around 90∘ was measured as shown in

Figure 3(c) The oscillator spectral response in Figure 3(d)shows the LVCQO spectral response wherein phase noisemeasured is minus107 dBcHz at an offset of 100KHz from thetuned frequency of 10MHz this response is measured byTektronix spectrum analyzer (RSA306B) [35]

This result is better as compared to that in [14] Anew method of examining the VCO tuning error (120573) isadopted by measuring the shift (Δ119891) in 119891119900 at phase cross-overfrequency The tested value of 120573 in the overall tuning rangeof 1MHzsim10MHz was observed to be less than 45

6 Conclusion

A new design of ETAF function and its subsequent applica-tion to the implementation of aVCQOwith linear-tuning laware presented The active blocks are commercially availableCFA (AD844) and four-quadrant multiplier (AD835) whichare readily available IC modules Responses of the functioncircuits are verified experimentally with PSPICE simulationand hardware testsThe quadrature oscillator had been tunedby control voltage (119881) in a linear range (band-spread) of05 le 119891119900 (MHZ) le 99 at low THD The design does notneed any additional current processing circuitry hence thereis no extra quiescent dissipation Power dissipation of theproposed oscillator circuit is about 33mW The circuit ispractically active-insensitive relative to device-port track-error (120576) Analysis on the effects of device parasitic com-ponents indicates insignificant effect on design equationseven though parasitic capacitors tend to limit the usablehigh-frequency range In this work a relatively new buildingblock namely the MMCC had been utilized for the voltage(119881) controlled linearly tunable quadrature oscilator designwith 107 dBcHz phase noise at 100KHz offset as shown inFigure 3(d) Thus a comparatively better quality result hadbeen obtained as is shown in Table 2

Active and Passive Electronic Components 7

It may be seen in Tables 1 and 2 that in the cited designsactive devices used are certain primary blocks with auxiliaryvoltagecurrent differencing unit (VDUCDU) or differentialamplifiers with their associated parasitics which tend to limitthe desired range of frequency (119891119901 or 119891119900) [6] Also tuningby 119892119898 or 119868119887 needs additional current processing circuitswith parasitic capacitors The authors believe that owing tosuch topological distinction the frequency tuning ranges aresomewhat lower However in the case of design by VDIBA[10] the range improves owing to the fact that the active com-ponent OPA-860 has itself a bandwidth (BW) of 470MHzIn the proposed design no such VDUCDU and 119892119898-to-119868119887conversion circuitry are used this circuit is structured withcommercially available AD844 (BW = 60MHz) and AD835(250MHz) ICmodules to achieve relatively higher frequencywherein effects of port-mismatch roll-off poles and parasiticshad been included in support

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] S J G Gift ldquoApplication of all-pass filters in the design ofmultiphase sinusoidal systemsrdquoMicroelectronics Journal vol 31no 1 pp 9ndash13 2000

[2] M Higashimura and Y Fukui ldquoRealization of current mode all-pass networks using a current conveyorrdquo IEEE Transactions onCircuits and Systems vol 37 no 5 pp 660-661 1990

[3] S Oztayfun S Kilinc A Celebi and U Cam ldquoA new elec-tronically tunable phase shifter employing current-controlledcurrent conveyorsrdquo International Journal of Electronics andCommunications vol 62 no 3 pp 228ndash231 2008

[4] S Minaei and O Cicekoglu ldquoA Resistorless realization of thefirst-order all-pass filterrdquo International Journal of Electronicsvol 93 no 3 pp 177ndash183 2006

[5] F Yucel and E Yuce ldquoCCII based more tunable voltage-modeall-pass filters and their quadrature oscillator applicationsrdquoInternational Journal of Electronics and Communications vol68 no 1 pp 1ndash9 2014

[6] A Toker and S Ozoguz ldquoNovel all-pass filter section usingdifferential difference amplifierrdquo International Journal of Elec-tronics and Communications vol 58 no 2 pp 153ndash155 2004

[7] J-W Horng C-M Wu and N Herencsar ldquoFully differentialfirst-order allpass filters using a DDCCrdquo Indian Journal ofEngineering and Materials Sciences vol 21 no 4 pp 345ndash3502014

[8] T Tsukutani H Tsunetsugu Y Sumi andN Yabuki ldquoElectron-ically tunable first-order all-pass circuit employing DVCC andOTArdquo International Journal of Electronics vol 97 no 3 pp 285ndash293 2010

[9] M A Ibrahim S Minaei and E Yuce ldquoAll-pass sections withrich cascadability and IC realization suitabilityrdquo InternationalJournal of CircuitTheory andApplications vol 40 no 5 pp 461ndash472 2012

[10] N Herencsar S Minaei J Koton E Yuce and K Vrba ldquoNewresistorless and electronically tunable realization of dual-outputVM all-pass filter using VDIBArdquo Analog Integrated Circuits andSignal Processing vol 74 no 1 pp 141ndash154 2013

[11] A U Keskin K Pal and E Hancioglu ldquoResistorless first-orderall-pass filter with electronic tuningrdquo International Journal ofElectronics and Communications vol 62 no 4 pp 304ndash3062008

[12] S Maheshwari and M S Ansari ldquoCatalog of realizationsfor dxccii using commercially available ics and applicationsrdquoRadioengineering vol 21 no 1 pp 281ndash289 2012

[13] S J G Gift and BMaundy ldquoAn improvedmultiphase sinusoidaloscillator using current feedback amplifierrdquo International Jour-nal of Electronics vol 4 pp 177ndash187 2016

[14] H-P Chen Y-S Hwang Y-T Ku S-F Wang and C-HWu ldquoVoltage-mode universal biquadratic filter and quadratureoscillator using CFAsrdquo IEICE Electronics Express vol 13 no 15pp 1ndash11 2016

[15] R Sotner J Jerabek N Herencsar J-W Horng K Vrba and TDostal ldquoSimple oscillator with enlarged tunability range basedon ECCII and VGA utilizing commercially available analogmultiplierrdquo Measurement Science Review vol 16 no 2 pp 35ndash41 2016

[16] S Siripongdee and W Jaikla ldquoElectronically controllablegrounded inductance simulators using single commerciallyavailable IC LT1228rdquo International Journal of Electronics andCommunications vol 76 pp 1ndash10 2017

[17] S J G Gift and B Maundy ldquoVersatile composite amplifierconfigurationrdquo International Journal of Electronics vol 102 no6 pp 993ndash1006 2014

[18] Y-S HwangW-H Liu S-H Tu and J-J Chen ldquoNew buildingblock multiplication-mode current conveyorrdquo IET CircuitsDevices and Systems vol 3 no 1 pp 41ndash48 2009

[19] ldquoAnalog Devices AD-835 250 MHz voltage output four quad-rantmultiplierrdquo httpwwwanalogcomdatasheetsAD835pdf

[20] ldquoIntersil datasheet file 24775 Sept 1998 28634 Apr 1999rdquo[21] ldquoAnalog devices Linear products data-book (MA USA)rdquo 1990[22] E Yuce and SMinaei ldquoAmodifiedCFOA and its applications to

simulated inductors capacitancemultipliers and analog filtersrdquoIEEE Transactions on Circuits and Systems vol 55 no 1 pp266ndash275 2008

[23] K Kumwachara and W Surakampontorn ldquoAn integrabletemperature-insensitive gm-RC quadrature oscillatorrdquo Interna-tional Journal of Electronics vol 90 no 9 pp 599ndash605 2003

[24] J-W Horng ldquoQuadrature oscillators using operational ampli-fiersrdquoActive and Passive Electronic Component vol 2011 ArticleID 320367 4 pages 2011

[25] A LahiriW Jaikla andM Siripruchyanun ldquoFirst CFOA-basedexplicit-current-output quadrature sinusoidal oscillators usinggrounded capacitorsrdquo International Journal of Electronics vol100 no 2 pp 259ndash273 2013

[26] J Jin and CWang ldquoSingle CDTA-based current-mode quadra-ture oscillatorrdquo International Journal of Electronics and Commu-nications vol 66 no 11 pp 933ndash936 2012

[27] F Khateb W Jaikla D Kubanek and N Khatib ldquoElectronicallytunable voltage-mode quadrature oscillator based on highperformance CCCDBArdquo Analog Integrated Circuits and SignalProcessing vol 74 no 3 pp 499ndash505 2013

[28] W Sa-Ngiamvibool and A Jantakun ldquoQuadrature oscillatorusing CCCCTAs and grounded capacitors with amplitudecontrollabilityrdquo International Journal of Electronics vol 101 no12 pp 1737ndash1758 2014

[29] N Pandey and R Pandey ldquoApproach for third order quadratureoscillator realisationrdquo IET Circuits Devices and Systems vol 9no 3 pp 161ndash171 2015

4 Active and Passive Electronic Components

Table 2 Comparative description of recent QO designs

Ref Device used Electronic tunability Linear tuning law 119891119900 reported (Hz) Tuning by THD ()[5] DO-CCII No No 233M 119877119862 117sim282[10] VDIBA Yes No 85M radic119868119887 225[12] CFA No No 909K 119877119862 mdash[14] CFA No No 398K 119877119862 142[23] OTA Yes Yes 64K 119868119887 mdash[24] VOA No No 160K 119877119862 mdash[25] CFOA No No 159K 119877119862 316[26] CDTA Yes No 173M radic119868119887 30[27] CCCDBA Yes No 419K radic119868119887 2sim12[28] CCCCTA Yes No 11M radic119892119898 1sim29[29] OTA Yes No 159M radic119892119898 1sim22Proposed CFA-MMCC Yes Yes sim102M 119881 09 sim28

The function119872(119904) relates to the MMCC block it is decom-posed as119872(119904) = 119872119900(119904) sdot 119872119890(119904) where119872119900 = 1119904120591119900 and

119872119890 (119904) = 1[(119904119901119894 + 1) (119904119901V + 1) (119904119901119911 + 1)] (15)

It has been observed that the 3 dB corner frequenciesfor all the port-transfer ratios appear at close proximity andhence these may be assumed equal without loss of generality[22] Therefore calculations for examining the effects of theroll-off poles become simpler if wewrite1199011sim5 equiv 1120596119901Writing119906 = (120596120596119901) ≪ 1 and solving for (11) we get

Δ 1 (119895120596) = 11 minus 1199062 + 2119895119906 (16)

which implies |Δ 1| = radic(1+41199062) asymp 1 and NΔ 1 = arctan(2119906) asymp0 Similar results are checked for (12) to (14) For the effects ofthe MMCC roll-off we put 120595 = (120596120596119898) ≪ 1 where 119901119894V119911 equiv1120596119898 solving (15) we get

119872119890 (119895120596) = 1[(1 minus 31205952) + 1198953120595 1 minus (12059523)] (17)

which reduces to |119872119890| = 1 and N119872119890 = minus arctan(3120595) asymp 0This analysis indicates that effects of roll-off poles of the activebuilding blocks are quite negligible in the range of operatingfrequencies (119891 lt 119891119901119898)4 LVCQO Implementation

Quadrature oscillators find diverse application in mea-surement systems [30ndash33] and in communication circuitsquadrature mixers SSB-modulator vector generator anddata conversion A comprehensive summary of recent QOdesigns is listed in Table 2 It may be seen that even thougha number of such oscillators were reported very few arelinearly tunable

We now present the linear VCO as implemented byforming a regenerative feedback loop formed with the ETAFin Figure 1(a) and the ETI in Figure 2 transfer of ETI is

119867(119904) = 1119904120591119900 (1 + 120585) + (119877119900119903119911) (18)

MMCC

k

V

x

w

z

Vi y1

y2 +

Vo

CzCo rzRo

Figure 2 Electronically tunable integrator (ETI)

where 120591119900 = 119877119900119862119900119896119881 120585 = 119862119900119862119911 ≪ 1 and 119877119900119903119911 ≪1 hence 119867(119904) = 1119904120591119900 Grounding of the capacitor (119862)facilitates absorbing119862119911 in119862-values at predesign level Deviceimperfection relative to port-transfer roll-off pole frequencies(120596119886119887120574) is estimated by writing

119867(119904) = (119886119887120574)119904120591119900 equiv (1 minus 120576119879)(119904120591119900) (19)

where 120576119879 = (120576119894 + 120576V + 120576119911) ≪ 1The deviation due to roll-off is

= ( 119904120596119886) + 1(

119904120596119887) + 1(

119904120596120574) + 1 (20)

As in previous section if we assume 120596119886119887120574 asymp 120596119898 and put 120595 =(120596120596119898) then reduces similar to (17) as

| = 1N = minus arctan (3120595) asymp 0 (21)

Active and Passive Electronic Components 5

020406080

100120140160180

(A)(B)

Frequency (Hz)

0

6

(dB)

20M10M1M500k

(B) (6 MHz V = 6

(A) (9 MHz V = 9 vＩＦＮs)

minus6

∘

e | fp (－（Ｔ)

(A) 31∘ Ｎ fp = 90

(B) 12∘ Ｎ fp = 60

vＩＦＮs)

(a)

02 04 06 08 1001

025

05

075

1

THD

()

Vip (volt)

9MHz6 Mhz

(b)

Time (sec)0

Am

plitu

de (v

olt)

00

75

minus75

500n250n

(c)

(d)

1 4 7 100

Simulation

Freq

uenc

y (H

z)

10M

5M

V (dc volt)

Hardware (C = 40 Ｊ R = 400Ω)Hardware (C = 80 Ｊ R = 400Ω)

(e)

Figure 3 Continued

6 Active and Passive Electronic Components

Quadrature phase error THD

2 066 1610 28

080 085 090 095 100 105 110 115 120

01020304050

Gain-crossover point

0

(C)

(B)

Gai

n (d

B)

(A)minus10

minus20

minus30

minus40

minus50

(C) (8 MHz)(B) (4 MHz)(A) (1－Ｔ)

fo (－（Ｔ)(Δ)

12∘

24∘

31∘

∘

u = (ffo)

(f)

Figure 3 Measured response of ETAF and QO (a) AP phase response (A) = 9Vdc (B) = 6Vdc (b) AP-THD () to 7th harmonic (c)QO wave response tuned at 10MHz quadrature signals at 119881119900 and 119864119900 nodes (d) QO spectral response of 10MHz for phase-noise evaluation(e) QO linear-tuning response (f) Measured tuning error of VCO

Now implementation of oscillator is derived by equating 1 minus119866119867(119904) equiv 0 which gives the characteristic equation (CE)

CE 1199042120591119900120591 + 119904 (120591119900 minus 120591) + 1 = 0Realizability condition 120591119900 = 120591

119877 = 119877119900119862 = 119862119900

Oscillation frequency 120596119900 = 119896119881119877119862

(22)

So tuned frequency (119891119900 in Hz) is linearly and directlyvariable by control voltage (119881)

119891119900 = 119881(20120587119877119862) (23)

The proposed method provides direct electronic tunabil-ity of oscillation frequency by the control voltage (119881) Noadditional current processing circuitry for 119892119898 to bias current(119868119887) conversion is needed as seen in the previous designsshown in Table 1 and thermal voltage (119881119879) is not involvedIt may be seen that 120596119900 is practically active-insensitive 119878120576120596119900 asymp05120576 ≪ 15 Experimental Results

The response of 119881-tunability of the proposed ETAF andLVCQO had been verified by PSPICE simulation [34] andhardware tests these are shown in Figure 3 ETAF responsesalong with its phase error (120579119890) and THD (measured to 7thharmonic) are shown in Figures 3(a) and 3(b) which arerelatively low compared to [10 24 25] Some small phaseerror (120579119890) on the experimentally generated sinusoid quadra-ture signals deviated around 90∘ was measured as shown in

Figure 3(c) The oscillator spectral response in Figure 3(d)shows the LVCQO spectral response wherein phase noisemeasured is minus107 dBcHz at an offset of 100KHz from thetuned frequency of 10MHz this response is measured byTektronix spectrum analyzer (RSA306B) [35]

This result is better as compared to that in [14] Anew method of examining the VCO tuning error (120573) isadopted by measuring the shift (Δ119891) in 119891119900 at phase cross-overfrequency The tested value of 120573 in the overall tuning rangeof 1MHzsim10MHz was observed to be less than 45

6 Conclusion

A new design of ETAF function and its subsequent applica-tion to the implementation of aVCQOwith linear-tuning laware presented The active blocks are commercially availableCFA (AD844) and four-quadrant multiplier (AD835) whichare readily available IC modules Responses of the functioncircuits are verified experimentally with PSPICE simulationand hardware testsThe quadrature oscillator had been tunedby control voltage (119881) in a linear range (band-spread) of05 le 119891119900 (MHZ) le 99 at low THD The design does notneed any additional current processing circuitry hence thereis no extra quiescent dissipation Power dissipation of theproposed oscillator circuit is about 33mW The circuit ispractically active-insensitive relative to device-port track-error (120576) Analysis on the effects of device parasitic com-ponents indicates insignificant effect on design equationseven though parasitic capacitors tend to limit the usablehigh-frequency range In this work a relatively new buildingblock namely the MMCC had been utilized for the voltage(119881) controlled linearly tunable quadrature oscilator designwith 107 dBcHz phase noise at 100KHz offset as shown inFigure 3(d) Thus a comparatively better quality result hadbeen obtained as is shown in Table 2

Active and Passive Electronic Components 7

It may be seen in Tables 1 and 2 that in the cited designsactive devices used are certain primary blocks with auxiliaryvoltagecurrent differencing unit (VDUCDU) or differentialamplifiers with their associated parasitics which tend to limitthe desired range of frequency (119891119901 or 119891119900) [6] Also tuningby 119892119898 or 119868119887 needs additional current processing circuitswith parasitic capacitors The authors believe that owing tosuch topological distinction the frequency tuning ranges aresomewhat lower However in the case of design by VDIBA[10] the range improves owing to the fact that the active com-ponent OPA-860 has itself a bandwidth (BW) of 470MHzIn the proposed design no such VDUCDU and 119892119898-to-119868119887conversion circuitry are used this circuit is structured withcommercially available AD844 (BW = 60MHz) and AD835(250MHz) ICmodules to achieve relatively higher frequencywherein effects of port-mismatch roll-off poles and parasiticshad been included in support

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] S J G Gift ldquoApplication of all-pass filters in the design ofmultiphase sinusoidal systemsrdquoMicroelectronics Journal vol 31no 1 pp 9ndash13 2000

[2] M Higashimura and Y Fukui ldquoRealization of current mode all-pass networks using a current conveyorrdquo IEEE Transactions onCircuits and Systems vol 37 no 5 pp 660-661 1990

[3] S Oztayfun S Kilinc A Celebi and U Cam ldquoA new elec-tronically tunable phase shifter employing current-controlledcurrent conveyorsrdquo International Journal of Electronics andCommunications vol 62 no 3 pp 228ndash231 2008

[4] S Minaei and O Cicekoglu ldquoA Resistorless realization of thefirst-order all-pass filterrdquo International Journal of Electronicsvol 93 no 3 pp 177ndash183 2006

[5] F Yucel and E Yuce ldquoCCII based more tunable voltage-modeall-pass filters and their quadrature oscillator applicationsrdquoInternational Journal of Electronics and Communications vol68 no 1 pp 1ndash9 2014

[6] A Toker and S Ozoguz ldquoNovel all-pass filter section usingdifferential difference amplifierrdquo International Journal of Elec-tronics and Communications vol 58 no 2 pp 153ndash155 2004

[7] J-W Horng C-M Wu and N Herencsar ldquoFully differentialfirst-order allpass filters using a DDCCrdquo Indian Journal ofEngineering and Materials Sciences vol 21 no 4 pp 345ndash3502014

[8] T Tsukutani H Tsunetsugu Y Sumi andN Yabuki ldquoElectron-ically tunable first-order all-pass circuit employing DVCC andOTArdquo International Journal of Electronics vol 97 no 3 pp 285ndash293 2010

[9] M A Ibrahim S Minaei and E Yuce ldquoAll-pass sections withrich cascadability and IC realization suitabilityrdquo InternationalJournal of CircuitTheory andApplications vol 40 no 5 pp 461ndash472 2012

[10] N Herencsar S Minaei J Koton E Yuce and K Vrba ldquoNewresistorless and electronically tunable realization of dual-outputVM all-pass filter using VDIBArdquo Analog Integrated Circuits andSignal Processing vol 74 no 1 pp 141ndash154 2013

[11] A U Keskin K Pal and E Hancioglu ldquoResistorless first-orderall-pass filter with electronic tuningrdquo International Journal ofElectronics and Communications vol 62 no 4 pp 304ndash3062008

[12] S Maheshwari and M S Ansari ldquoCatalog of realizationsfor dxccii using commercially available ics and applicationsrdquoRadioengineering vol 21 no 1 pp 281ndash289 2012

[13] S J G Gift and BMaundy ldquoAn improvedmultiphase sinusoidaloscillator using current feedback amplifierrdquo International Jour-nal of Electronics vol 4 pp 177ndash187 2016

[14] H-P Chen Y-S Hwang Y-T Ku S-F Wang and C-HWu ldquoVoltage-mode universal biquadratic filter and quadratureoscillator using CFAsrdquo IEICE Electronics Express vol 13 no 15pp 1ndash11 2016

[15] R Sotner J Jerabek N Herencsar J-W Horng K Vrba and TDostal ldquoSimple oscillator with enlarged tunability range basedon ECCII and VGA utilizing commercially available analogmultiplierrdquo Measurement Science Review vol 16 no 2 pp 35ndash41 2016

[16] S Siripongdee and W Jaikla ldquoElectronically controllablegrounded inductance simulators using single commerciallyavailable IC LT1228rdquo International Journal of Electronics andCommunications vol 76 pp 1ndash10 2017

[17] S J G Gift and B Maundy ldquoVersatile composite amplifierconfigurationrdquo International Journal of Electronics vol 102 no6 pp 993ndash1006 2014

[18] Y-S HwangW-H Liu S-H Tu and J-J Chen ldquoNew buildingblock multiplication-mode current conveyorrdquo IET CircuitsDevices and Systems vol 3 no 1 pp 41ndash48 2009

[19] ldquoAnalog Devices AD-835 250 MHz voltage output four quad-rantmultiplierrdquo httpwwwanalogcomdatasheetsAD835pdf

[20] ldquoIntersil datasheet file 24775 Sept 1998 28634 Apr 1999rdquo[21] ldquoAnalog devices Linear products data-book (MA USA)rdquo 1990[22] E Yuce and SMinaei ldquoAmodifiedCFOA and its applications to

simulated inductors capacitancemultipliers and analog filtersrdquoIEEE Transactions on Circuits and Systems vol 55 no 1 pp266ndash275 2008

[23] K Kumwachara and W Surakampontorn ldquoAn integrabletemperature-insensitive gm-RC quadrature oscillatorrdquo Interna-tional Journal of Electronics vol 90 no 9 pp 599ndash605 2003

[24] J-W Horng ldquoQuadrature oscillators using operational ampli-fiersrdquoActive and Passive Electronic Component vol 2011 ArticleID 320367 4 pages 2011

[25] A LahiriW Jaikla andM Siripruchyanun ldquoFirst CFOA-basedexplicit-current-output quadrature sinusoidal oscillators usinggrounded capacitorsrdquo International Journal of Electronics vol100 no 2 pp 259ndash273 2013

[26] J Jin and CWang ldquoSingle CDTA-based current-mode quadra-ture oscillatorrdquo International Journal of Electronics and Commu-nications vol 66 no 11 pp 933ndash936 2012

[27] F Khateb W Jaikla D Kubanek and N Khatib ldquoElectronicallytunable voltage-mode quadrature oscillator based on highperformance CCCDBArdquo Analog Integrated Circuits and SignalProcessing vol 74 no 3 pp 499ndash505 2013

[28] W Sa-Ngiamvibool and A Jantakun ldquoQuadrature oscillatorusing CCCCTAs and grounded capacitors with amplitudecontrollabilityrdquo International Journal of Electronics vol 101 no12 pp 1737ndash1758 2014

[29] N Pandey and R Pandey ldquoApproach for third order quadratureoscillator realisationrdquo IET Circuits Devices and Systems vol 9no 3 pp 161ndash171 2015

Active and Passive Electronic Components 5

020406080

100120140160180

(A)(B)

Frequency (Hz)

0

6

(dB)

20M10M1M500k

(B) (6 MHz V = 6

(A) (9 MHz V = 9 vＩＦＮs)

minus6

∘

e | fp (－（Ｔ)

(A) 31∘ Ｎ fp = 90

(B) 12∘ Ｎ fp = 60

vＩＦＮs)

(a)

02 04 06 08 1001

025

05

075

1

THD

()

Vip (volt)

9MHz6 Mhz

(b)

Time (sec)0

Am

plitu

de (v

olt)

00

75

minus75

500n250n

(c)

(d)

1 4 7 100

Simulation

Freq

uenc

y (H

z)

10M

5M

V (dc volt)

Hardware (C = 40 Ｊ R = 400Ω)Hardware (C = 80 Ｊ R = 400Ω)

(e)

Figure 3 Continued

6 Active and Passive Electronic Components

Quadrature phase error THD

2 066 1610 28

080 085 090 095 100 105 110 115 120

01020304050

Gain-crossover point

0

(C)

(B)

Gai

n (d

B)

(A)minus10

minus20

minus30

minus40

minus50

(C) (8 MHz)(B) (4 MHz)(A) (1－Ｔ)

fo (－（Ｔ)(Δ)

12∘

24∘

31∘

∘

u = (ffo)

(f)

Figure 3 Measured response of ETAF and QO (a) AP phase response (A) = 9Vdc (B) = 6Vdc (b) AP-THD () to 7th harmonic (c)QO wave response tuned at 10MHz quadrature signals at 119881119900 and 119864119900 nodes (d) QO spectral response of 10MHz for phase-noise evaluation(e) QO linear-tuning response (f) Measured tuning error of VCO

Now implementation of oscillator is derived by equating 1 minus119866119867(119904) equiv 0 which gives the characteristic equation (CE)

CE 1199042120591119900120591 + 119904 (120591119900 minus 120591) + 1 = 0Realizability condition 120591119900 = 120591

119877 = 119877119900119862 = 119862119900

Oscillation frequency 120596119900 = 119896119881119877119862

(22)

So tuned frequency (119891119900 in Hz) is linearly and directlyvariable by control voltage (119881)

119891119900 = 119881(20120587119877119862) (23)

The proposed method provides direct electronic tunabil-ity of oscillation frequency by the control voltage (119881) Noadditional current processing circuitry for 119892119898 to bias current(119868119887) conversion is needed as seen in the previous designsshown in Table 1 and thermal voltage (119881119879) is not involvedIt may be seen that 120596119900 is practically active-insensitive 119878120576120596119900 asymp05120576 ≪ 15 Experimental Results

The response of 119881-tunability of the proposed ETAF andLVCQO had been verified by PSPICE simulation [34] andhardware tests these are shown in Figure 3 ETAF responsesalong with its phase error (120579119890) and THD (measured to 7thharmonic) are shown in Figures 3(a) and 3(b) which arerelatively low compared to [10 24 25] Some small phaseerror (120579119890) on the experimentally generated sinusoid quadra-ture signals deviated around 90∘ was measured as shown in

Figure 3(c) The oscillator spectral response in Figure 3(d)shows the LVCQO spectral response wherein phase noisemeasured is minus107 dBcHz at an offset of 100KHz from thetuned frequency of 10MHz this response is measured byTektronix spectrum analyzer (RSA306B) [35]

This result is better as compared to that in [14] Anew method of examining the VCO tuning error (120573) isadopted by measuring the shift (Δ119891) in 119891119900 at phase cross-overfrequency The tested value of 120573 in the overall tuning rangeof 1MHzsim10MHz was observed to be less than 45

6 Conclusion

A new design of ETAF function and its subsequent applica-tion to the implementation of aVCQOwith linear-tuning laware presented The active blocks are commercially availableCFA (AD844) and four-quadrant multiplier (AD835) whichare readily available IC modules Responses of the functioncircuits are verified experimentally with PSPICE simulationand hardware testsThe quadrature oscillator had been tunedby control voltage (119881) in a linear range (band-spread) of05 le 119891119900 (MHZ) le 99 at low THD The design does notneed any additional current processing circuitry hence thereis no extra quiescent dissipation Power dissipation of theproposed oscillator circuit is about 33mW The circuit ispractically active-insensitive relative to device-port track-error (120576) Analysis on the effects of device parasitic com-ponents indicates insignificant effect on design equationseven though parasitic capacitors tend to limit the usablehigh-frequency range In this work a relatively new buildingblock namely the MMCC had been utilized for the voltage(119881) controlled linearly tunable quadrature oscilator designwith 107 dBcHz phase noise at 100KHz offset as shown inFigure 3(d) Thus a comparatively better quality result hadbeen obtained as is shown in Table 2

Active and Passive Electronic Components 7

It may be seen in Tables 1 and 2 that in the cited designsactive devices used are certain primary blocks with auxiliaryvoltagecurrent differencing unit (VDUCDU) or differentialamplifiers with their associated parasitics which tend to limitthe desired range of frequency (119891119901 or 119891119900) [6] Also tuningby 119892119898 or 119868119887 needs additional current processing circuitswith parasitic capacitors The authors believe that owing tosuch topological distinction the frequency tuning ranges aresomewhat lower However in the case of design by VDIBA[10] the range improves owing to the fact that the active com-ponent OPA-860 has itself a bandwidth (BW) of 470MHzIn the proposed design no such VDUCDU and 119892119898-to-119868119887conversion circuitry are used this circuit is structured withcommercially available AD844 (BW = 60MHz) and AD835(250MHz) ICmodules to achieve relatively higher frequencywherein effects of port-mismatch roll-off poles and parasiticshad been included in support

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] S J G Gift ldquoApplication of all-pass filters in the design ofmultiphase sinusoidal systemsrdquoMicroelectronics Journal vol 31no 1 pp 9ndash13 2000

[2] M Higashimura and Y Fukui ldquoRealization of current mode all-pass networks using a current conveyorrdquo IEEE Transactions onCircuits and Systems vol 37 no 5 pp 660-661 1990

[3] S Oztayfun S Kilinc A Celebi and U Cam ldquoA new elec-tronically tunable phase shifter employing current-controlledcurrent conveyorsrdquo International Journal of Electronics andCommunications vol 62 no 3 pp 228ndash231 2008

[4] S Minaei and O Cicekoglu ldquoA Resistorless realization of thefirst-order all-pass filterrdquo International Journal of Electronicsvol 93 no 3 pp 177ndash183 2006

[5] F Yucel and E Yuce ldquoCCII based more tunable voltage-modeall-pass filters and their quadrature oscillator applicationsrdquoInternational Journal of Electronics and Communications vol68 no 1 pp 1ndash9 2014

[6] A Toker and S Ozoguz ldquoNovel all-pass filter section usingdifferential difference amplifierrdquo International Journal of Elec-tronics and Communications vol 58 no 2 pp 153ndash155 2004

[7] J-W Horng C-M Wu and N Herencsar ldquoFully differentialfirst-order allpass filters using a DDCCrdquo Indian Journal ofEngineering and Materials Sciences vol 21 no 4 pp 345ndash3502014

[8] T Tsukutani H Tsunetsugu Y Sumi andN Yabuki ldquoElectron-ically tunable first-order all-pass circuit employing DVCC andOTArdquo International Journal of Electronics vol 97 no 3 pp 285ndash293 2010

[9] M A Ibrahim S Minaei and E Yuce ldquoAll-pass sections withrich cascadability and IC realization suitabilityrdquo InternationalJournal of CircuitTheory andApplications vol 40 no 5 pp 461ndash472 2012

[10] N Herencsar S Minaei J Koton E Yuce and K Vrba ldquoNewresistorless and electronically tunable realization of dual-outputVM all-pass filter using VDIBArdquo Analog Integrated Circuits andSignal Processing vol 74 no 1 pp 141ndash154 2013

[11] A U Keskin K Pal and E Hancioglu ldquoResistorless first-orderall-pass filter with electronic tuningrdquo International Journal ofElectronics and Communications vol 62 no 4 pp 304ndash3062008

[12] S Maheshwari and M S Ansari ldquoCatalog of realizationsfor dxccii using commercially available ics and applicationsrdquoRadioengineering vol 21 no 1 pp 281ndash289 2012

[13] S J G Gift and BMaundy ldquoAn improvedmultiphase sinusoidaloscillator using current feedback amplifierrdquo International Jour-nal of Electronics vol 4 pp 177ndash187 2016

[14] H-P Chen Y-S Hwang Y-T Ku S-F Wang and C-HWu ldquoVoltage-mode universal biquadratic filter and quadratureoscillator using CFAsrdquo IEICE Electronics Express vol 13 no 15pp 1ndash11 2016

[15] R Sotner J Jerabek N Herencsar J-W Horng K Vrba and TDostal ldquoSimple oscillator with enlarged tunability range basedon ECCII and VGA utilizing commercially available analogmultiplierrdquo Measurement Science Review vol 16 no 2 pp 35ndash41 2016

[16] S Siripongdee and W Jaikla ldquoElectronically controllablegrounded inductance simulators using single commerciallyavailable IC LT1228rdquo International Journal of Electronics andCommunications vol 76 pp 1ndash10 2017

[17] S J G Gift and B Maundy ldquoVersatile composite amplifierconfigurationrdquo International Journal of Electronics vol 102 no6 pp 993ndash1006 2014

[18] Y-S HwangW-H Liu S-H Tu and J-J Chen ldquoNew buildingblock multiplication-mode current conveyorrdquo IET CircuitsDevices and Systems vol 3 no 1 pp 41ndash48 2009

[19] ldquoAnalog Devices AD-835 250 MHz voltage output four quad-rantmultiplierrdquo httpwwwanalogcomdatasheetsAD835pdf

[20] ldquoIntersil datasheet file 24775 Sept 1998 28634 Apr 1999rdquo[21] ldquoAnalog devices Linear products data-book (MA USA)rdquo 1990[22] E Yuce and SMinaei ldquoAmodifiedCFOA and its applications to

simulated inductors capacitancemultipliers and analog filtersrdquoIEEE Transactions on Circuits and Systems vol 55 no 1 pp266ndash275 2008

[23] K Kumwachara and W Surakampontorn ldquoAn integrabletemperature-insensitive gm-RC quadrature oscillatorrdquo Interna-tional Journal of Electronics vol 90 no 9 pp 599ndash605 2003

[24] J-W Horng ldquoQuadrature oscillators using operational ampli-fiersrdquoActive and Passive Electronic Component vol 2011 ArticleID 320367 4 pages 2011

[25] A LahiriW Jaikla andM Siripruchyanun ldquoFirst CFOA-basedexplicit-current-output quadrature sinusoidal oscillators usinggrounded capacitorsrdquo International Journal of Electronics vol100 no 2 pp 259ndash273 2013

[26] J Jin and CWang ldquoSingle CDTA-based current-mode quadra-ture oscillatorrdquo International Journal of Electronics and Commu-nications vol 66 no 11 pp 933ndash936 2012

[27] F Khateb W Jaikla D Kubanek and N Khatib ldquoElectronicallytunable voltage-mode quadrature oscillator based on highperformance CCCDBArdquo Analog Integrated Circuits and SignalProcessing vol 74 no 3 pp 499ndash505 2013

[28] W Sa-Ngiamvibool and A Jantakun ldquoQuadrature oscillatorusing CCCCTAs and grounded capacitors with amplitudecontrollabilityrdquo International Journal of Electronics vol 101 no12 pp 1737ndash1758 2014

[29] N Pandey and R Pandey ldquoApproach for third order quadratureoscillator realisationrdquo IET Circuits Devices and Systems vol 9no 3 pp 161ndash171 2015

6 Active and Passive Electronic Components

Quadrature phase error THD

2 066 1610 28

080 085 090 095 100 105 110 115 120

01020304050

Gain-crossover point

0

(C)

(B)

Gai

n (d

B)

(A)minus10

minus20

minus30

minus40

minus50

(C) (8 MHz)(B) (4 MHz)(A) (1－Ｔ)

fo (－（Ｔ)(Δ)

12∘

24∘

31∘

∘

u = (ffo)

(f)

Figure 3 Measured response of ETAF and QO (a) AP phase response (A) = 9Vdc (B) = 6Vdc (b) AP-THD () to 7th harmonic (c)QO wave response tuned at 10MHz quadrature signals at 119881119900 and 119864119900 nodes (d) QO spectral response of 10MHz for phase-noise evaluation(e) QO linear-tuning response (f) Measured tuning error of VCO

Now implementation of oscillator is derived by equating 1 minus119866119867(119904) equiv 0 which gives the characteristic equation (CE)

CE 1199042120591119900120591 + 119904 (120591119900 minus 120591) + 1 = 0Realizability condition 120591119900 = 120591

119877 = 119877119900119862 = 119862119900

Oscillation frequency 120596119900 = 119896119881119877119862

(22)

So tuned frequency (119891119900 in Hz) is linearly and directlyvariable by control voltage (119881)

119891119900 = 119881(20120587119877119862) (23)

The proposed method provides direct electronic tunabil-ity of oscillation frequency by the control voltage (119881) Noadditional current processing circuitry for 119892119898 to bias current(119868119887) conversion is needed as seen in the previous designsshown in Table 1 and thermal voltage (119881119879) is not involvedIt may be seen that 120596119900 is practically active-insensitive 119878120576120596119900 asymp05120576 ≪ 15 Experimental Results

The response of 119881-tunability of the proposed ETAF andLVCQO had been verified by PSPICE simulation [34] andhardware tests these are shown in Figure 3 ETAF responsesalong with its phase error (120579119890) and THD (measured to 7thharmonic) are shown in Figures 3(a) and 3(b) which arerelatively low compared to [10 24 25] Some small phaseerror (120579119890) on the experimentally generated sinusoid quadra-ture signals deviated around 90∘ was measured as shown in

Figure 3(c) The oscillator spectral response in Figure 3(d)shows the LVCQO spectral response wherein phase noisemeasured is minus107 dBcHz at an offset of 100KHz from thetuned frequency of 10MHz this response is measured byTektronix spectrum analyzer (RSA306B) [35]

This result is better as compared to that in [14] Anew method of examining the VCO tuning error (120573) isadopted by measuring the shift (Δ119891) in 119891119900 at phase cross-overfrequency The tested value of 120573 in the overall tuning rangeof 1MHzsim10MHz was observed to be less than 45

6 Conclusion

A new design of ETAF function and its subsequent applica-tion to the implementation of aVCQOwith linear-tuning laware presented The active blocks are commercially availableCFA (AD844) and four-quadrant multiplier (AD835) whichare readily available IC modules Responses of the functioncircuits are verified experimentally with PSPICE simulationand hardware testsThe quadrature oscillator had been tunedby control voltage (119881) in a linear range (band-spread) of05 le 119891119900 (MHZ) le 99 at low THD The design does notneed any additional current processing circuitry hence thereis no extra quiescent dissipation Power dissipation of theproposed oscillator circuit is about 33mW The circuit ispractically active-insensitive relative to device-port track-error (120576) Analysis on the effects of device parasitic com-ponents indicates insignificant effect on design equationseven though parasitic capacitors tend to limit the usablehigh-frequency range In this work a relatively new buildingblock namely the MMCC had been utilized for the voltage(119881) controlled linearly tunable quadrature oscilator designwith 107 dBcHz phase noise at 100KHz offset as shown inFigure 3(d) Thus a comparatively better quality result hadbeen obtained as is shown in Table 2

Active and Passive Electronic Components 7

It may be seen in Tables 1 and 2 that in the cited designsactive devices used are certain primary blocks with auxiliaryvoltagecurrent differencing unit (VDUCDU) or differentialamplifiers with their associated parasitics which tend to limitthe desired range of frequency (119891119901 or 119891119900) [6] Also tuningby 119892119898 or 119868119887 needs additional current processing circuitswith parasitic capacitors The authors believe that owing tosuch topological distinction the frequency tuning ranges aresomewhat lower However in the case of design by VDIBA[10] the range improves owing to the fact that the active com-ponent OPA-860 has itself a bandwidth (BW) of 470MHzIn the proposed design no such VDUCDU and 119892119898-to-119868119887conversion circuitry are used this circuit is structured withcommercially available AD844 (BW = 60MHz) and AD835(250MHz) ICmodules to achieve relatively higher frequencywherein effects of port-mismatch roll-off poles and parasiticshad been included in support

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] S J G Gift ldquoApplication of all-pass filters in the design ofmultiphase sinusoidal systemsrdquoMicroelectronics Journal vol 31no 1 pp 9ndash13 2000

[2] M Higashimura and Y Fukui ldquoRealization of current mode all-pass networks using a current conveyorrdquo IEEE Transactions onCircuits and Systems vol 37 no 5 pp 660-661 1990

[3] S Oztayfun S Kilinc A Celebi and U Cam ldquoA new elec-tronically tunable phase shifter employing current-controlledcurrent conveyorsrdquo International Journal of Electronics andCommunications vol 62 no 3 pp 228ndash231 2008

[4] S Minaei and O Cicekoglu ldquoA Resistorless realization of thefirst-order all-pass filterrdquo International Journal of Electronicsvol 93 no 3 pp 177ndash183 2006

[5] F Yucel and E Yuce ldquoCCII based more tunable voltage-modeall-pass filters and their quadrature oscillator applicationsrdquoInternational Journal of Electronics and Communications vol68 no 1 pp 1ndash9 2014

[6] A Toker and S Ozoguz ldquoNovel all-pass filter section usingdifferential difference amplifierrdquo International Journal of Elec-tronics and Communications vol 58 no 2 pp 153ndash155 2004

[7] J-W Horng C-M Wu and N Herencsar ldquoFully differentialfirst-order allpass filters using a DDCCrdquo Indian Journal ofEngineering and Materials Sciences vol 21 no 4 pp 345ndash3502014

[8] T Tsukutani H Tsunetsugu Y Sumi andN Yabuki ldquoElectron-ically tunable first-order all-pass circuit employing DVCC andOTArdquo International Journal of Electronics vol 97 no 3 pp 285ndash293 2010

[9] M A Ibrahim S Minaei and E Yuce ldquoAll-pass sections withrich cascadability and IC realization suitabilityrdquo InternationalJournal of CircuitTheory andApplications vol 40 no 5 pp 461ndash472 2012

[10] N Herencsar S Minaei J Koton E Yuce and K Vrba ldquoNewresistorless and electronically tunable realization of dual-outputVM all-pass filter using VDIBArdquo Analog Integrated Circuits andSignal Processing vol 74 no 1 pp 141ndash154 2013

[11] A U Keskin K Pal and E Hancioglu ldquoResistorless first-orderall-pass filter with electronic tuningrdquo International Journal ofElectronics and Communications vol 62 no 4 pp 304ndash3062008

[12] S Maheshwari and M S Ansari ldquoCatalog of realizationsfor dxccii using commercially available ics and applicationsrdquoRadioengineering vol 21 no 1 pp 281ndash289 2012

[13] S J G Gift and BMaundy ldquoAn improvedmultiphase sinusoidaloscillator using current feedback amplifierrdquo International Jour-nal of Electronics vol 4 pp 177ndash187 2016

[14] H-P Chen Y-S Hwang Y-T Ku S-F Wang and C-HWu ldquoVoltage-mode universal biquadratic filter and quadratureoscillator using CFAsrdquo IEICE Electronics Express vol 13 no 15pp 1ndash11 2016

[15] R Sotner J Jerabek N Herencsar J-W Horng K Vrba and TDostal ldquoSimple oscillator with enlarged tunability range basedon ECCII and VGA utilizing commercially available analogmultiplierrdquo Measurement Science Review vol 16 no 2 pp 35ndash41 2016

[16] S Siripongdee and W Jaikla ldquoElectronically controllablegrounded inductance simulators using single commerciallyavailable IC LT1228rdquo International Journal of Electronics andCommunications vol 76 pp 1ndash10 2017

[17] S J G Gift and B Maundy ldquoVersatile composite amplifierconfigurationrdquo International Journal of Electronics vol 102 no6 pp 993ndash1006 2014

[18] Y-S HwangW-H Liu S-H Tu and J-J Chen ldquoNew buildingblock multiplication-mode current conveyorrdquo IET CircuitsDevices and Systems vol 3 no 1 pp 41ndash48 2009

[19] ldquoAnalog Devices AD-835 250 MHz voltage output four quad-rantmultiplierrdquo httpwwwanalogcomdatasheetsAD835pdf

[20] ldquoIntersil datasheet file 24775 Sept 1998 28634 Apr 1999rdquo[21] ldquoAnalog devices Linear products data-book (MA USA)rdquo 1990[22] E Yuce and SMinaei ldquoAmodifiedCFOA and its applications to

simulated inductors capacitancemultipliers and analog filtersrdquoIEEE Transactions on Circuits and Systems vol 55 no 1 pp266ndash275 2008

[23] K Kumwachara and W Surakampontorn ldquoAn integrabletemperature-insensitive gm-RC quadrature oscillatorrdquo Interna-tional Journal of Electronics vol 90 no 9 pp 599ndash605 2003

[24] J-W Horng ldquoQuadrature oscillators using operational ampli-fiersrdquoActive and Passive Electronic Component vol 2011 ArticleID 320367 4 pages 2011

[25] A LahiriW Jaikla andM Siripruchyanun ldquoFirst CFOA-basedexplicit-current-output quadrature sinusoidal oscillators usinggrounded capacitorsrdquo International Journal of Electronics vol100 no 2 pp 259ndash273 2013

[26] J Jin and CWang ldquoSingle CDTA-based current-mode quadra-ture oscillatorrdquo International Journal of Electronics and Commu-nications vol 66 no 11 pp 933ndash936 2012

[27] F Khateb W Jaikla D Kubanek and N Khatib ldquoElectronicallytunable voltage-mode quadrature oscillator based on highperformance CCCDBArdquo Analog Integrated Circuits and SignalProcessing vol 74 no 3 pp 499ndash505 2013

[28] W Sa-Ngiamvibool and A Jantakun ldquoQuadrature oscillatorusing CCCCTAs and grounded capacitors with amplitudecontrollabilityrdquo International Journal of Electronics vol 101 no12 pp 1737ndash1758 2014

[29] N Pandey and R Pandey ldquoApproach for third order quadratureoscillator realisationrdquo IET Circuits Devices and Systems vol 9no 3 pp 161ndash171 2015

Active and Passive Electronic Components 7

It may be seen in Tables 1 and 2 that in the cited designsactive devices used are certain primary blocks with auxiliaryvoltagecurrent differencing unit (VDUCDU) or differentialamplifiers with their associated parasitics which tend to limitthe desired range of frequency (119891119901 or 119891119900) [6] Also tuningby 119892119898 or 119868119887 needs additional current processing circuitswith parasitic capacitors The authors believe that owing tosuch topological distinction the frequency tuning ranges aresomewhat lower However in the case of design by VDIBA[10] the range improves owing to the fact that the active com-ponent OPA-860 has itself a bandwidth (BW) of 470MHzIn the proposed design no such VDUCDU and 119892119898-to-119868119887conversion circuitry are used this circuit is structured withcommercially available AD844 (BW = 60MHz) and AD835(250MHz) ICmodules to achieve relatively higher frequencywherein effects of port-mismatch roll-off poles and parasiticshad been included in support

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] S J G Gift ldquoApplication of all-pass filters in the design ofmultiphase sinusoidal systemsrdquoMicroelectronics Journal vol 31no 1 pp 9ndash13 2000

[2] M Higashimura and Y Fukui ldquoRealization of current mode all-pass networks using a current conveyorrdquo IEEE Transactions onCircuits and Systems vol 37 no 5 pp 660-661 1990

[3] S Oztayfun S Kilinc A Celebi and U Cam ldquoA new elec-tronically tunable phase shifter employing current-controlledcurrent conveyorsrdquo International Journal of Electronics andCommunications vol 62 no 3 pp 228ndash231 2008

[4] S Minaei and O Cicekoglu ldquoA Resistorless realization of thefirst-order all-pass filterrdquo International Journal of Electronicsvol 93 no 3 pp 177ndash183 2006

[5] F Yucel and E Yuce ldquoCCII based more tunable voltage-modeall-pass filters and their quadrature oscillator applicationsrdquoInternational Journal of Electronics and Communications vol68 no 1 pp 1ndash9 2014

[6] A Toker and S Ozoguz ldquoNovel all-pass filter section usingdifferential difference amplifierrdquo International Journal of Elec-tronics and Communications vol 58 no 2 pp 153ndash155 2004

[7] J-W Horng C-M Wu and N Herencsar ldquoFully differentialfirst-order allpass filters using a DDCCrdquo Indian Journal ofEngineering and Materials Sciences vol 21 no 4 pp 345ndash3502014

[8] T Tsukutani H Tsunetsugu Y Sumi andN Yabuki ldquoElectron-ically tunable first-order all-pass circuit employing DVCC andOTArdquo International Journal of Electronics vol 97 no 3 pp 285ndash293 2010

[9] M A Ibrahim S Minaei and E Yuce ldquoAll-pass sections withrich cascadability and IC realization suitabilityrdquo InternationalJournal of CircuitTheory andApplications vol 40 no 5 pp 461ndash472 2012

[10] N Herencsar S Minaei J Koton E Yuce and K Vrba ldquoNewresistorless and electronically tunable realization of dual-outputVM all-pass filter using VDIBArdquo Analog Integrated Circuits andSignal Processing vol 74 no 1 pp 141ndash154 2013

[11] A U Keskin K Pal and E Hancioglu ldquoResistorless first-orderall-pass filter with electronic tuningrdquo International Journal ofElectronics and Communications vol 62 no 4 pp 304ndash3062008

[12] S Maheshwari and M S Ansari ldquoCatalog of realizationsfor dxccii using commercially available ics and applicationsrdquoRadioengineering vol 21 no 1 pp 281ndash289 2012

[13] S J G Gift and BMaundy ldquoAn improvedmultiphase sinusoidaloscillator using current feedback amplifierrdquo International Jour-nal of Electronics vol 4 pp 177ndash187 2016

[14] H-P Chen Y-S Hwang Y-T Ku S-F Wang and C-HWu ldquoVoltage-mode universal biquadratic filter and quadratureoscillator using CFAsrdquo IEICE Electronics Express vol 13 no 15pp 1ndash11 2016

[15] R Sotner J Jerabek N Herencsar J-W Horng K Vrba and TDostal ldquoSimple oscillator with enlarged tunability range basedon ECCII and VGA utilizing commercially available analogmultiplierrdquo Measurement Science Review vol 16 no 2 pp 35ndash41 2016

[16] S Siripongdee and W Jaikla ldquoElectronically controllablegrounded inductance simulators using single commerciallyavailable IC LT1228rdquo International Journal of Electronics andCommunications vol 76 pp 1ndash10 2017

[17] S J G Gift and B Maundy ldquoVersatile composite amplifierconfigurationrdquo International Journal of Electronics vol 102 no6 pp 993ndash1006 2014

[18] Y-S HwangW-H Liu S-H Tu and J-J Chen ldquoNew buildingblock multiplication-mode current conveyorrdquo IET CircuitsDevices and Systems vol 3 no 1 pp 41ndash48 2009

[19] ldquoAnalog Devices AD-835 250 MHz voltage output four quad-rantmultiplierrdquo httpwwwanalogcomdatasheetsAD835pdf

[20] ldquoIntersil datasheet file 24775 Sept 1998 28634 Apr 1999rdquo[21] ldquoAnalog devices Linear products data-book (MA USA)rdquo 1990[22] E Yuce and SMinaei ldquoAmodifiedCFOA and its applications to

simulated inductors capacitancemultipliers and analog filtersrdquoIEEE Transactions on Circuits and Systems vol 55 no 1 pp266ndash275 2008

[23] K Kumwachara and W Surakampontorn ldquoAn integrabletemperature-insensitive gm-RC quadrature oscillatorrdquo Interna-tional Journal of Electronics vol 90 no 9 pp 599ndash605 2003

[24] J-W Horng ldquoQuadrature oscillators using operational ampli-fiersrdquoActive and Passive Electronic Component vol 2011 ArticleID 320367 4 pages 2011

[25] A LahiriW Jaikla andM Siripruchyanun ldquoFirst CFOA-basedexplicit-current-output quadrature sinusoidal oscillators usinggrounded capacitorsrdquo International Journal of Electronics vol100 no 2 pp 259ndash273 2013

[26] J Jin and CWang ldquoSingle CDTA-based current-mode quadra-ture oscillatorrdquo International Journal of Electronics and Commu-nications vol 66 no 11 pp 933ndash936 2012

[27] F Khateb W Jaikla D Kubanek and N Khatib ldquoElectronicallytunable voltage-mode quadrature oscillator based on highperformance CCCDBArdquo Analog Integrated Circuits and SignalProcessing vol 74 no 3 pp 499ndash505 2013

[28] W Sa-Ngiamvibool and A Jantakun ldquoQuadrature oscillatorusing CCCCTAs and grounded capacitors with amplitudecontrollabilityrdquo International Journal of Electronics vol 101 no12 pp 1737ndash1758 2014

[29] N Pandey and R Pandey ldquoApproach for third order quadratureoscillator realisationrdquo IET Circuits Devices and Systems vol 9no 3 pp 161ndash171 2015

8 Active and Passive Electronic Components

[30] J Raman P Rombouts and L Weyten ldquoSimple quadratureoscillator for BISTrdquo Electronics Letters vol 46 no 4 pp 271ndash273 2010

[31] D Chen W Yang and M Pan ldquoDesign of impedance measur-ing circuits based on phase-sensitive demodulation techniquerdquoIEEE Transactions on Instrumentation and Measurement vol60 no 4 pp 1276ndash1282 2011

[32] S YoderM Ismail andW KhalilVCO-Based Quantizers UsingFrequency-to-Digital and Time-to-Digital Converters Springer-Briefs in Electrical and Computer Engineering Springer Sc +Busines Media LLC New York NY USA 2011

[33] S Liang and W Redman-White ldquoA linear tuning ring VCO forspectrum monitor receiver in cognitive radio applicationsrdquo inProceedings of the 20th European Conference on Circuit Theoryand Design (ECCTD rsquo11) pp 65ndash68 IEEE Linkoping SwedenAugust 2011

[34] ldquoMacromodel of AD-844 AN in PSPICE Library MicrosimCorp Irvine USArdquo 1992

[35] httpwwwtekcomspectrum-analyzerrsa306

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Active and Passive Electronic Components

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VLSI Design

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