7/27/2019 Microwave group.pdf

1/5

M.Tech.Projects(MicrowaveGroup:SKK,AB,MPA,KR)

201314

GATEEntry(ProjectNo.s16):

1. ElectromagneticBandGap(EBG)structuresforEMI/EMCSignalintegrity:MPAAB

The simultaneous switching noise (SSN) or ground bounce noise

(GBN)thatoccursinthepower/ground(P/G)planesusedtodeliverpower

inmultilayerPCBsandpackageshasbecomeanissueofmajorconcernwith

regard to highspeed digital circuitswith higher clock frequencies, faster

deviceswitchingspeed,andlowerdrivingvoltagelevels.SSNcausedbyfast

timevarying

currents

can

excite

the

cavity

resonance

modes

between

parallel plate waveguideshaped P/G planes and can cause significant

problems forthesignal/power integrity (SI/PI)aswellaselectromagnetic

interference (EMI).Tobuilda stablepowerdistributionnetwork (PDN) in

highspeeddigitalcircuitswithanalog/RFcircuits,SSNshouldbesufficiently

suppressedintheentirefrequencyrangeuptoseveralgigahertz.

Thisproject intendsto investigateplanarEBGstructuresasameans

ofbothsuppressingthenoisepropagationfromDCtoseveralgigahertzand

minimizing the effect of the perforated reference plane on highspeed

signallines.

2. Independentlytunabledualbandhighimpedancesurfaces:MPASKKHighImpedanceSurfaces (HIS)haveability to realize relatively low

profile,highgainandhighefficiencyantennasystemsincloseproximityto

metallicsurfaces.Suchsystemsentailthedesignoftwomaincomponents

namelyHISgroundplanesandnarrowbandantennaswhicharedesigned

toresonate

at

the

forbidden

frequency

bands

of

the

HIS

ground

planes.

At

the forbidden frequency bands of the HIS ground planes they exhibit

surface wave suppression and inphase reflection characteristics for

incident electromagnetic (EM) planewave excitationwhich have formed

thebasisofvariousantennaapplicationsusingHIS.

7/27/2019 Microwave group.pdf

2/5

However, for wideband antennas the operational frequency

bandwidth is limited by that of the HIS ground plane. Hence, in such

scenarioatunableHISgroundplanecouldofferthemeanstoachievewider

effective bandwidth. This can be achieved by employing a wideband

antennamounted

on

top

of

areconfigurable

HIS

ground

plane

whose

reflectioncoefficientmagnitudeandhence itsoperationalfrequencyband

couldbecontrolledbyanexternalstimulisuchasaDCbiasvoltage.

3. UltrathinandbroadbandHIS:MPASKKUltrathinelectromagneticabsorbersconsistingofhigh impedancesurfaces

developed in recent years are characterized by an electrical thickness of

much lessthan/4attheoperatingfrequency.However,theysufferfrom

narrow operating bandwidths, greatly limiting their utility in most

applications.Ultrathinandsimultaneouslywidebandabsorbersareurgently

desired. In this project, we intend to design, analyze and fabricate an

ultrathin high impedance surface absorber at microwave frequencies.

Unliketheconventionalultrathinabsorbers,theproposedabsorbershould

exhibitwidebandabsorptionpropertiesdemonstratednumericallyaswell

asexperimentally. (Here, thebandwidth isdefinedas the frequencyband

wherethereflectivityislessthan 10dB).

4. DesignandoptimizationofMultibranchDohertyPAdesign:KRABDoherty power amplifier (PA) design is based on load modulation

technique;where, thepower transistorwill always seeanoptimum load

over input power drive. Since 3G and 4G communication signals are

envelopevarying,therefore,theirenvelopepowervariesfromanaverage

value to certain peak values. Such signals have peak to average power

ratios(PAPR)

ranging

typically

from

6to

10

dB.

Moreover,

the

instantaneous efficiency of a typical PA varies with input power drive,

therefore,maximumDCtoRFconversionefficiencycanonlybeachievedat

peak saturated output power of the PA. Thus, in presence of envelope

varyingsignalswithhighPAPR,thePAisoperatedatcertainaveragepower

7/27/2019 Microwave group.pdf

3/5

backoff lower than itspeaksaturatedpowerresulting into loweraverage

efficiency. A conventional Doherty PA architecture utilizes an auxiliary

amplifierwhichmodulates the load seen by themain amplifier resulting

intohighaverageefficiencyevenat lowerpowerdrive.By increasing the

numberof

auxiliary

amplifiers,

one

can

achieve

high

efficiency

over

awide

range of input power drive. However, the input power splitting and a

propercombinationoftheoutputpowerisstillafieldofstudyintheMulti

branchDohertyPA inorder toobtainoptimumperformance in termsof

efficiencyandlinearity.Thisprojectwillinvolvethedesignandoptimization

ofmultibranchDohertyAmplifierbasedonGaN/GaAsHEMTdeviceswith

otherassociatedcircuitsprintedoverPCB.

5. InvertedDohertyAmplifierwithoptimizationbasedonphaseoffsetlines:KRAB.

InvertedDohertypoweramplifier(PA)issimilarinoperationasDohertyPA

(Topic1) andutilizes loadmodulation technique,where, a transistorwill

always see an optimum load over input power drive. However, unlike

Doherty PA, a transformer less design can be obtained in an inverted

DohertyPA

architecture,

where,

aphase

offset

lines

will

proper

load

modulation and output power combination. Such transformer less

architecture has a potential to be extended for multiband/broadband

application.Also,amultibranchtransformer less invertedDohertyPA isa

potential area of investigation. This projectwill involve the design and

optimization of multibranch Transformer less inverted Doherty PA. A

propertopologyforphaseoffsetline,where,arequiredphaseshiftcanbe

achievedovercertain frequency rangewillbea key researcharea in this

design. Thedesignwill bebasedonGaN/GaAsHEMTdeviceswith other

associatedcircuitsprintedoverPCB.

6. ReconfigurableActiveAntenna:ABMPA7. RFID(Subin):MPA

7/27/2019 Microwave group.pdf

4/5

DRDO+Navy(tobeconfirmed)

8. ParametricAmplifierusingVaractors:KRAB9. RFProximitySensor:ABMPA10.HEMTbasedswitchesinMIC(ParulGupta):SKKAB11.PCBMEMS:AB+SC12.RFSystem(PritikanaDebnath):SKKKR13.ReentrantCoupler(Sayed):ABSKK14.MEMS:SKKKR

7/27/2019 Microwave group.pdf

5/5