EC6304_EC_I-QB

KSK COLLEGE OF ENGG & TECH EC6304-ELECTRONIC CIRCUITS I YEAR /SEM:II/III

K. S. K COLLEGE OF ENGINEERING & TECHNOLOGYDEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

B.E. ECE-R 2013-ChennaiSyllabus

Sub.Code : EC6304 Branch / Year / SEM: ECE / II / III Sub.Name : ELECTRONIC CIRCUITS I Batch : 2013-2017Staff Name : Mrs.A.SUJITHA Academic Year: 2015-2016 (Odd Sem)

L T P C 3 1 0 4

OBJECTIVES:The student should be made to Learn about biasing of BJTs and MOSFETs Design and construct amplifiers Construct amplifiers with active loads Study high frequency response of all amplifiers

UNIT I BIASING OF DISCRETE BJT AND MOSFET 9DC Load line, operating point, Various biasing methods for BJT-Design-Stability-Bias

compensation,Thermal stability, Design of biasing for JFET, Design of biasing for MOSFETUNIT II BJT AMPLIFIERS 9

Small signal Analysis of Common Emitter-AC Loadline, Voltage swing limitations, Common collector and common base amplifiers – Differential amplifiers- CMRR- Darlington Amplifier,Bootstrap technique - Cascaded stages - Cascode AmplifierUNIT III JFET AND MOSFET AMPLIFIERS 9

Small signal analysis of JFT amplifiers- Small signal Analysis of MOSFET and JFET, Common source amplifier, Voltage swing limitations, Small signal analysis of MOSFET and JFET Source follower and Common Gate amplifiers, - BiMOS Cascode amplifierUNIT IV FREQUENCY ANALYSIS OF BJT AND MOSFET AMPLIFIERS 9

Low frequency and Miller effect, High frequency analysis of CE and MOSFET CS amplifier, Shortcircuit current gain, cut off frequency – f α and fβ unity gain and Determination of bandwidth of single stage and multistage amplifiersUNIT V IC MOSFET AMPLIFIERS 9

IC Amplifiers- IC biasing Current steering circuit using MOSFET- MOSFET current sources- PMOSand NMOS current sources. Amplifier with active loads - enhancement load, Depletion load andPMOS and NMOS current sources load- CMOS common source and source follower- CMOS differential amplifier- CMRR.

TOTAL (L : 45 + T : 15) : 60 PERIODSTEXT BOOK:

1. Donald .A. Neamen, Electronic Circuit Analysis and Design –2 ndEdition,Tata Mc GrawHill, 2009.REFERENCES:

1. Adel .S. Sedra, Kenneth C. Smith, “Micro Electronic Circuits”, 6thEdition, Oxford University Press, 2010.41

2. David A., “Bell Electronic Devices and Circuits”, Oxford Higher Education Press, 5thEditon, 2010

3. Behzad Razavi, “Design of Analog CMOS Integrated Circuits”, Tata Mc Graw Hill, 2007. 4. Paul Gray, Hurst, Lewis, Meyer “Analysis and Design of Analog Integrated Circuits”, 4thEdition ,John Willey & Sons 2005 5. Millman.J. and Halkias C.C, “Integrated Electronics”, Mc Graw Hill, 2001. 6. D.Schilling and C.Belove, “Electronic Circuits”, 3rdEdition, Mc Graw Hill, 1989

A.SUJITHA,AP/ECE KSKCET


UNIT–I

BIASING OF DISCRETE BJT AND MOSFET

PART – A

1. Define - Stability Factor. [May/June 2012], [Nov/Dec 2009], [Apr/May 2010], [May/June 2012]

2. Compare bias stabilization and compensation techniques. [Nov/Dec 2011]

3. What is the condition for thermal stability? [Nov/Dec 2007]

4. What are the different methods of biasing JFET? [May/June 2012]

5. What are the types of transistor biasing? [Nov/Dec 2011]

6. Draw the single stage self biased circuit using pnp transistor. [Apr/May 2011]

7. List the advantages of self bias. [ Nov/Dec 2012]

8. Draw the fixed bias and the self bias circuits. [ Nov/Dec 2009], [ May/Jun 2007]

9. What is the need for biasing in transistor amplifier?

[Apr/May 2011]

10. What is reverse saturation current? [May/June 2012]

11. Calculate the value of feedback resistor (Rs) required to self bias an N-channel JFET with

IDSS=40mA, VP = -10V and VGSQ = -5V. [ Apr/May 2010]

12. What is DC load line? How is Q point plotted on the DC load line? [Nov/Dec 2012]

13. What is the function of the Q point?

[nov/dec 2013]

14. What is thermal stability?

[nov/dec 2013]

15. Define the term biasing.

[May-2013]

16. How can collector current be stabilized with respect to Ico variations?

[Nov-2010]

17. Derive stability factor for fixed bias circuit.

[Nov- 2010].

18. What are the operating regions of N channel MOSFET and how do you identify the operating

region?

[Nov- 2014]

19. Find the collector and base current of circuit given in fig hfe=100,VBE=0.7V

[nov-14]



20. List out the importance of selecting the proper operating point. [may-15]

21. Draw a DC load line of the circuit shown [may-15]

PART – B

1. Explain fixed biasing in BJT and FET. Explain the procedure for locating operating point on the

characteristic curves and derive an expression for the stability factor. (16) [ May/June 2012]

2. Draw a voltage divider bias BJT network. Derive expressions for ICQ and VCEQ and describe the

method of drawing the dc load line on the output characteristics of transistor derive an

expression for the stability factor. (16) [June 2012,2010]

3. A silicon transistor with β = 49 is used in self bias arrangement with VCC = 5V, RE = 1Kohms

and IE = 1mA. Find the values of R1 and R2 such that the stability factor does not exceed 5. (10)

[ Nov/Dec 2012]

4. In an N-channel JFET, biased by potential divider method, the operating point has to be at IDSS =

12mA. If VDD = 12V, R1 = 20K Ω and R2 = 10K Ω, RD =1.2K Ω and VP= -4V. Find the values of

ID, VGS, VG, VDS and VS. (16) [ Nov/Dec 2012]

5. Calculate the operating point for the following circuit. (6) [Apr/May 2011]



Vcc=15V

1 k o h m

1 0 0 o h m

2 0 0 o h m

.

6. For the following circuit calculate VCE and IC, where β = 100 for the silicon transistor.

. [ May/June 2012]

7. Derive the expression of stability factor for collector feedback amplifier. (10)[ Apr/May 2011]

8. Explain the circuit that uses a diode to compensate the changes in VBE and ICO. (12) [May 2010]

9. Explain the operation of thermistor compensation. (4) [ Apr/May 2010]

10. Explain the various techniques of stabilization of Q-point in a transistor. (16) [May/June 2012]

11. Explain the factors on which an amplifier needs to be stabilized. (6) [ Nov/Dec 2012]

12. With the help of neat diagram, explain the methods used in biasing the FET and MOSFET.

(16)

[Nov/Dec 2011]

13. (i) Define - Stability Factor (2)

(ii) The pnp transistor in the following circuit has β = 50. Find the values of RC to obtain

Vc = 5V. What happens if the transistor is replaced with another transistor β = 100? (14)

. [ Apr/May 2011]


β=50


14. (i) Draw the circuit of a voltage divider bias circuit. Explain its operation and discuss

how it stabilizes against VBE changes. (8)

(ii) Derive the stability factor of the voltage divider bias circuit.Compare the stability factor of fixed bias and voltage divider bias circuits with hFE =100, Re = 1KΩ, R1 = 33KΩ and R2 = 12 KΩ. (8)[nov/dec 2013]

15. (i) Explain the circuit of gate bias for providing stabilization of JFET. (8)

(ii) Sketch the bias circuit for enhancement MOSFETs and explain its

operation. (8)[Nov-2013]

16. For the Circuit in the Figure-1 , draw the AC load line and determine the maximum output swing without distortion.

(8)[may/june-13]

17. Discuss in detail about the various bias compensation techniques.

(8)[may/june 2013]

18. Locate the operating point for the below figure ,Vcc=15v,hf=200

(8) [nov/dec 2010]



19. Design a self bias circuit for JFET to be biased in pinch off region . Given Vdd=20,Vgb=-

4v,Idss=8mA.Draw the designed circuit. (8) (Nov-2010]

20. i)Design Emitter bias for BJT with Ic=2mA,Vcc=18V,VCE=10V and β=150. (8)

ii)Derive the stability factor of self bias circuit of BJT. (8) [Nov-2014]

21. Design voltage divider bias circuit for NMOS, such that

IDQ=400µA,VDD=14V,VDS=2.3V,kn=µnCox(W/L)=1mA/V2,Vt=1V. Assume a current of 1µA

through R1 and R2 and Vs=1.2V. (16)[Nov-2014]

22. The parameters for each transistor in the circuit given are hfe=100 and VBE(on)=0.7V. Determine

the Q point values of base, collector and emitter currents in Q1 and Q2. (8) [may-15]

23. Determine the change in collector current produced in each bias referred in figure, when the

circuit temperature raised from 25’C to 105’C and ICBO=15nA @25’C. (8) [may-15]

24. Determine the quiescent current and voltage values in a p channel JFET circuit (6) [may-15]



25. The circuit given let hfe=100.(1)Find Vth and Rth for the base circuit (2)Determine ICQ andVCEQ

(3)Draw the DC load line. (10)[may-15]

UNIT–II

BJT AMPLIFIERS

PART – A

1. Define h-parameters [May/June 2007]

2. Write the voltage gain equation for CE configuration including source resistance. [M/June 2012]

3. What is AC load line? How is Q point plotted on the AC load line?

4. Why are common emitter amplifiers more popular? [ Nov/Dec 2011]

5. How does the input impedance increase due to Darlington connection? [ Apr/May 2008]

6. Two identical amplifiers having 10 dB gain each are cascaded. Calculate the output, if the input

is of 1mV (p-p). [Apr/May 2011]

7. What is the coupling schemes used in multistage amplifiers? [ Apr/May 2010]

8. What is a cascade amplifier?

9. Determine the output voltage of a differential amplifier for the input voltages of 300 µV and

240µV. The differential gain of the amplifier is 5000 and the value of CMRR is 100. [N/D-12]



10. If CMRR of an amplifier is 100 dB and differential gain is 1000, calculate the common mode

gain. [Apr/May 2011]

11. What is the need of constant current circuit in differential amplifier? [May/June 2012]

12. State Bisection theorem. [ Nov/Dec 2012]

13. Define CMRR [Nov/Dec 2009], [Nov/Dec 2007] [ May/Jun 2007]

14. Define Miller’s Theorem [ May/June 2012], [Apr/May 2010]

15. What is the advantage of Darlington amplifier?

[nov/dec 2013]

16. Mention two important characteristics of CC circuit.

[nov/dec 2013]

17. Draw the circuit diagram of Darlington type amplifier.

[may/june2013]

18. Give the reason for the improvement of CMMR in the amplifier.

[may/june2013]

19. Draw darlington amplifier with bootstrap arrangement.

[nov/dec 2010]

20. Why CB amplifier is preferred for high frequency signal when compared to CE amplifier? [nov/dec 2010]

21. Draw the AC equivalent circuit for given figure. [Nov-2014]

22. Find CMRR of differential amplifier with differential gain of 300 and common mode gain of 0.2. [Nov-2014]

23. Define CMRR of BJT differential amplifier.How to improve it? [nov-15]

24. A small signal source Vi(t)=20cos20t + 30 sin106t is applied to a transistor amplifier as shown in fig. The transistor has hfe=150,ro=infinite and rπ=3kΩ. Determine Vo(t) [nov-15]

PART – B

1. Derive the expression for

a) Current gain,A.SUJITHA,AP/ECE KSKCET


b) Voltage gain,c) Input impedance and d) Output admittance. of a small signal transistor amplifier in terms of h parameters. (12) [ Apr/May 2010]

2. Explain the voltage swing limitations for a common emitter amplifier configuration.

3. A CC amplifier is fed with the voltage source Vs of internal resistance Rs = 800Ω. The load

resistance RL = 1600Ω. The CE hybrid parameters are hie = 1000Ω; hre = 2.2 x 10-4; hfe = 55;

hoe = 23 µA/V. Compute voltage gain, current gain, input resistance, output resistance using

approximate analysis. (8) [ May/June 2012]

4. Draw the small signal hybrid model of CE amplifier and derive the expression for its A I, AV, RI,

RO. (16) [ May/June 2012]

5. Compare CB, CE and CC amplifiers and state their applications.

(8) [ Nov/Dec 2011],[May/June 2012], [Nov/Dec 2009] [ Apr/May 2010]

6. Consider a single stage CE amplifier with RS = 1KΩ and RL = 1.2KΩ. Calculate Ai, Ri, AV,

power gain and Ro if hie = 1.1KΩ, hre = 2.5x10-4, hfe = 50 and hoe = 25 µA/V. (8) [ N/D 2011]

7. For the following circuit, find the voltage gain when the capacitance is connected across RE and

when capacitance is not connected across RE. (16) [ Apr/May 2011]

. . .

.

8. For the CC transistor amplifier circuit, find the expressions for input impedance and voltage

gain. Assume suitable model for the transistor. (16) [ Nov/Dec 2009]

9. (i) Describe the method to increase the input resistance using Darlington connection. (8)

(ii) Define CMRR (4)

(iii) Write short notes on multistage amplifiers. (4) [ Apr/May 2011]

10. Explain the operation of a Darlington emitter follower and also derive an expression for its

performance measures. (16) [ May/June 2012]

11. Explain the boot strapped Darlington emitter follower with circuit diagram. (8) [ May/June 2012]

12. Explain the operation of emitter coupled differential amplifier. (12)[ Apr/May 2010]


RL

C

RE

RB RC


13. Explain the transfer characteristics of the differential amplifier. (4) [ Apr/May 2010]

14. Draw the circuit of a CE amplifier with coupling and bypass capacitors. With the helpof its equivalent circuit, obtain the equation of the voltage gain, input and

output impedance. (16)[nov/dec2013]

15. Draw the circuit of a emitter coupled BJT differential amplifier and explain the

operation of the circuit. Explain how the differential amplifier with a constant current stage improves the CMRR.

(16)[nov/dec2013]16. Compute the parameters of the circuit shown in Figure – 2 with β = 100. (10)[MAY/JUNE-13]

17. Draw a differential amplifier and its AC equivalent circuit. Derive for Ac

and Ad.

18. Derive CMRR of differential amplifier with its equivalent circuit.

(16)[Nov-14]

19. Explain the operation of cascade amplifier and derive gain, input and

output impedance. (16)[Nov-14]

20. Consider the circuit shown with parameters are hfe=120 and

VA=infinite. (1)Determine the current gain, voltage gain, input impedance

and output impedance. (2)Find the maximum undistorted output voltage

swing. (12)[may-15]



21. Draw the circuit diagram of bootstrapped emitter follower with its equivalent

circuit, derive for its input and output impedance.

(6)[may-15]

UNIT–III

JFET AND MOSFET AMPLIFIERS

PART – A

1. What is an amplifier?

2. Write the expression for basic current equation in MOSFET.

3. Why FET is called as a voltage controlled device?

4. Draw the equivalent circuit of MOSFET.

5. State atleast two reasons why a hybrid parameter model is used in small signal analysis.

6. Sketch the simple common source amplifier circuit of MOSFET.

7. What are the basic circuit configurations used in MOSFET?

8. Sketch the simple common gate amplifier circuit of MOSFET.

9. Compare the characteristics of small signal and large signal amplifiers.

10. Compare the AC circuit characteristics of the CS, CG and CD.

11. State the general advantages of using JFET rather than BJT.

12. Draw the small signal equivalent circuit of JFET.

13. How does the body effect change the small signal equivalent circuit of MOSFET?

14. Write the applications of MOSFET.

15. Write the expression of small signal voltage gain and output resistance of the common gate

circuit.

16. What is the difference between MOSFET and PN junction FET?

17. Define amplifier rise time.

[nov/dec 2013]



18. Define bandwidth of an amplifier.

[nov/dec 2013]

19. Draw small signal model of JFET.

[Nov-14]

20. What are the features of BiMOS cascade amplifier?

[Nov-14]

21. Compare between JFET and MOSFET amplifiers.

[may-15]

PART-B

1. Draw the small signal hybrid model of common drain MOSFET amplifier and derive the

expression for Ai,Av,Ri,Rv.

2. Briefly explain about the small signal analysis of CS amplifier MOSFET?

3. With the neat sketch explain the principle of operation of cascode amplifier and also derive an

expression for its performance measures?

4. Write short notes on voltage swing limitations.

5. Briefly explain about the small signal analysis of JFET?

6. Derive gain, input and output impedance of common source JFET amplifier with neat

circuit diagram and equivalent circuit. (16)[Nov-14]

7. Derive gain, input and output impedance of MOSFET source follower with neat circuit

diagram and equivalent circuit. (16)[Nov-14]

8. Draw a discrete common gate JFET amplifier and derive voltage gain, input impedance and

output impedance with small signal equivalent circuit. (6)[may-15]

9. Determine the current gain of JFET source follower amplifier. (4) [may-15]

UNIT–IV

FREQUENCY ANALYSIS OF BJT AND MOSFET AMPLIFIERS

PART – A

1. Why are h parameters not used at high frequencies? [May/June 2012]

2. Write the expressions for gain bandwidth product for voltage and current. [ Apr/May 2010]

3. How is the high frequency gain of an amplifier limited? [May/June 2012]



4. Draw general frequency response curve of an amplifier. [ Nov/Dec 2007], [ May/Jun 2007]

5. What is bandwidth of an amplifier? [Nov/Dec 2009],[ May/Jun 2007]

6. What is the effect of coupling capacitors on the bandwidth of the amplifier. [Nov/Dec 2011]

7. Short circuit common emitter current gain of transistor is 25 at a frequency of 2 MHz if

fβ = 200KHz, calculate fT and hfe. What is the bandwidth that can be obtained using BJT, if

the rise time of a BJT is 40 nano seconds? [ Nov/Dec 2011]

8. What are the effects of emitter bypass capacitor on high frequency response? [Nov/Dec 2012]

9. What is meant by gain-bandwidth product? [Nov/Dec 2012] [Apr/May 2008]

10. Calculate the amplification factor, µ of FET, if rd = 4KΩ and gm = 4mA/V. [ Apr/May 2011]

11. Draw the high frequency model of MOSFET. [ May/June 2012]

12. Two amplifiers having gain 20 dB and 40 dB are cascaded. Find the overall gain in dB.

13. Write the equation of overall upper and lower cut off frequencies of multistage amplifiers.

14. What is the bandwidth that can be obtained using BJT, if the rise time of a BJT is 40 ns?

. [ May/ June 2012]

15. What is meant by amplifier rise time? [Nov/Dec 2007],[Apr/May 2010]

16. What is the effect of Millers capacitance on the frequency response of an amplifier? [Nov-14]

17. Relate gain and bandwidth of single and multi stage amplifier. [Nov-14]

18. Find the unity gain bandwidth of MOSFET whose gm=6mA/V, Cgs=8pF, Cgd=4pF

and Cds=1pF.[m-15]

PART – B

1. Define alpha cutoff frequency. (4) [May/June 2012]

2. Explain the significance of cut off frequencies and gain bandwidth product of amplifier. (6)

3. Explain the low frequency response and the high frequency response of an amplifier. (16)[M-10]

4. Draw the high frequency hybrid π model for a transistor in the CE configuration and explain the

significance of each component. (12) [ May/June 2012]

5. Explain in detail with neat diagram frequency response of BJT amplifier. Discuss the

significance of cut off frequencies and band width of the amplifier. (16) [ Nov/Dec 2011]

6. Using hybrid π model of a CE amplifier derive the expression for its short circuit gain. (16)

[ May/June 2012]

7. The following circuit has R = 100KΩ, Rin = 420KΩ, Cgs = Cgd = 1PF, gm = 4mA/V,



Rt = 3.33KΩ. Find the mid band gain and upper 3 dB frequency, fH . (16) [ Apr/May 2011]

.

8. Explain the operation of high frequency common source MOSFET amplifier with neat diagram.

Derive the expression for

(a) voltage gain

(b) input admittance

(c) input impedance

(d) output admittance (16) [ Apr/May 2010]

9. Draw the high frequency equivalent circuit of MOSFET amplifier and derive all the parameters

related to its frequency response. (16) [May/June 2012]

10. Explain the high frequency equivalent circuit of MOSFET and hence derive gain bandwidth

product for any one configuration. (16) [Nov/Dec 2009]

11. Derive the expression for frequency response of multistage amplifier. (10) [ Nov/Dec 2011]

12. Explain the frequency response of multistage amplifiers. Calculate the overall upper and lower

cut off frequencies. [ May/June 2012] (10) [Nov/Dec 2009]

13. How does Rise and Sag time related to cut-off frequencies? Justify. (8) [May/June 2012]

14. i)Derive fα,fβ anf fγ. (8)

ii)For the circuit shown find cut off frequencies due to C1 and C2. (8)[NOV-14]


Rin Vin

R

Cgs

gmVgs

RL


15. Explain the high frequency operation of common source amplifier with its equivalent circuit.

(16)[Nov-14]

16. Determine the voltage gain, input impedance, output impedance of CMOS source follower

amplifier. (8)[may-15]

UNIT–V

IC MOSFET AMPLIFIERS

PART – A

1. What are the three basic configurations of IC MOSFET amplifiers?

2. Describe the characteristics of CMOS CS amplifier.

3. How current sources are used to bias IC amplifiers.

4. What is IC biasing Current steering circuit using MOSFET?

5. What is the small signal behavior of an enhancement load?

6. Give the advantages of CMOS IC.

7. How does this “enhancement load” resemble a resistor?

8. What is the small signal behavior of an enhancement load?

9. Draw a circuit of current source using MOSFET. [Nov-14]

10. Draw a CMOS amplifier with NMOS driver and PMOS as active load. [Nov-14]

11. Compare NMOS amplifier with enhancement , depletion and resistive load. [m-15]

12. List out the advantages of CMOS differential amplifier over MOS differential amplifier [m-15]

PART – B

1. Explain the working principle of a simple MOSFET differential amplifier with an active load.

2. Derive the expression of the differential-mode voltage gain, common mode voltage gain and

CMRR for a MOSFET differential amplifier.

3. Explain the working principle of a CMOS differential amplifier.

4. Explain the design of a PMOS and NMOS current sources to provide a specified bias current and

output resistance.

5. Explain in detail the MOSFET amplifiers with enhancement load and depletion load.

6. Draw a MOS current steering circuit with two sink and two source terminals. Write the

expression for the terminal currents in terms of reference current. (16)[Nov-14]

7. Derive gain, input and output impedance of common source amplifier with NMOS

diode connected active load. (16)[Nov-14]


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