App of NonLinear Models for GaN HEMT PA Design

Application of NonApplication of Non--Linear Models in a Linear Models in a

range of challenging GaN HEMT Power range of challenging GaN HEMT Power

Amplifier Designs Amplifier Designs

Ray Pengelly, BradRay Pengelly, Brad MillonMillon, Don Farrell, , Don Farrell,

BillBill PribblePribble and Simon Woodand Simon Wood

WMC: Challenges in Model-Based HPA Design

Cree Inc., Research Triangle Park, NC 27709Cree Inc., Research Triangle Park, NC 27709

OutlineOutline

• Attributes of GaN HEMTs

• Cree GaN HEMT Models

• Design Examples

– Broadband CW Amplifiers

– Linear WiMAX Amplifier

• Future Model Improvements

• Conclusions

Attributes of GaNAttributes of GaN HEMTsHEMTs

• High Voltage Operation

• High power densities – 4 to 8 watts/mm at 28 and

50 volt operation respectively

• High Frequency Performance – present Cree process has fT of 25 GHz

• High Efficiency

• Low Quiescent Current

• High Native Linearity

• Low capacitance per peak watt (12% of LDMOS and 21% ofGaAs MESFET) – supports broad bandwidths

• Enable new amplifier architectures

• Highly correctable under DPD

• Almost constant CDS as a function of VDS – great for Drain Modulation

WideBan

dgap

Models for GaNModels for GaN HEMTsHEMTs

• Equivalent-circuit based approach

– Relatively simple extraction

– Process sensitive based on individual elements

– Simple implementation using commercial harmonic balance simulators

• Significant historical information for model basis and validation

• Non-linearity introduced as required by element

– Drain current source is dominant non-linearity

– Gate current formulation includes breakdown and forward conduction

– Voltage variations of parasitic capacitances derived from charge formulations

• Model data fit extends over drive, frequency, bias, and temperature

• Many hundreds of successful hybrid and MMIC designs

Model SchematicModel Schematic

vd1g

vg1

Port

P2

Num=2

SRL

SRL4

L=(ld/sc+ld1/(sc*scf)) nH

R=(rd/(sc*scf)) Ohm

R

R6

R=1e6 Ohm

pncap3X15

vgg0=-21 V

cg3=0.1

cg2=0.6

cg1=cgd pF

scf=scf

sc=sc

R

R3

R=0.01 Ohm

SRL

SRL1

L=(lg/sc+lg1/(scf*sc)) nH

R=(rg/sc+rg1/(sc*scf)) Ohm

pncap3

X12

vgg0=vgg0 V

cg3=cg3

cg2=cg2

cg1=cgs pF

scf=scfsc=sc

Port

P1

Num=1

R

R1

R=(ri/(sc*scf)) Ohm

Port

P5

Num=5

SRLSRL3

R=(rs/(sc*scf)) Ohm

L=(ls/sc) nH

Port

P4

Num=4

C

C8

C=30.0 nF

R

R2

R=rth Ohm

VCVS

SRC1

G=1

Port

P8

Num=8

C

C7

C=1.0 uF

R

R5R=1e6 Ohm

C

C9

C=(cds*sc*scf) pF

SDD6P

SDD6P1

Cport[1]=

C[1]=I[6,0]=(vdf)/5e4

I[5,0]=-vd*idt

I[4,0]=(_v4)*gmc

I[3,0]=(_v3)*gdsc

I[2,0]=id1

I[1,0]=(vg)/5e8

• Based on 13-element MESFET model (H. Kondoh – 1986 MTT-S)

• ADS version shown using non-linear equation-based elements

– Easily changed during design process

– Speed comparable to C-coded version

• AWR version uses C code with “model wizard”

Drain current

Thermal resistance

More details on More details on GaNGaN HEMT ModelHEMT Model

• Most FET models implement a gate current-control characteristic that transitions from the sub-threshold region to the linear gate control region directly, without treating the intermediate region, called the quadratic region. Fager et al. implemented an equation and new parameters to fit the quadratic region. This leads to better agreement with measured IMD and other nonlinear characteristics.

• Gate charge is partitioned into gate-source and gate-drain charge. Each charge expression is a function of both VDS and VGS. Using charge partitioning, it is possible to fit most GaN HEMT capacitance functions and observed charge conservation.

-15 -10 -5 0 5 8

Voltage (V)

gm and Ids

0

5

10

15

20

25

30

0

666.7

1333

2000

2667

3333

4000

p1

|S(2,1)|[1,X] (L)Schematic 1

IDC(I_METER.AMP1) (R, mA)Schematic 1

p1: Freq = 0.05 GHz

Sub

Threshold

Blue is DC transconductance

Red is drain current

Quad Linear Compression

Ids, mA

Gate voltage, volts

Gm, mS500

250

0-4 -3 -2 -1 0 0.5

• The model includes new capacitance functions as well as modeling of the drain-source breakdown and self heating.

• The model has four ports, with the extra port providing a measure of the temperature rise. The voltage between the external thermal circuit port and the source node is numerically equal to the junction temperature rise in degrees C. This occurs because the current source in the thermal circuit is numerically equal to the instantaneous power dissipated in the FET and the resistance, R_TH is numerically equal to the thermal resistance. The RC product of the thermal circuit is the thermal time constant.

• The model addresses the sharp turn-on knee in GaN HEMTs leading to the accurate prediction of IMD sweet spots in Class A/B operation.

More details on More details on GaNGaN HEMT ModelHEMT Model

Drain Current ModelDrain Current Model

-3 -2 -1 0 1-4 2

0.05

0.10

0.00

0.15

Vlow

gm

5 10 15 20 25 30 35 400 45

0.1

0.2

0.3

0.4

0.0

0.5

Vhigh

perm

ute(Is_high.i)

• Transconductance curve fit to Gm from small-signal model fits over bias range

• Output conductance dispersion model

• Peak current and knee voltage fit from load-pull - includes trap effects

• Pinch-off fit from DC IV-characteristics – gives model of drain current

• IV function similar to Fager-Statz formulation – good model of pinch-off needed to accurately predict intermodulation distortion

Temperature Dependence Temperature Dependence –– SelfSelf--heatingheating

34

34.5

35

35.5

36

36.5

0 50 100 150 200

chuck temp

output power

• Drain current is only temperature dependent model element

• Drain current scales to provide -0.1 dB/10oC reduction in power for current-limited load-line

• Self-heating included using a thermal resistance – calculated from finite element analysis of die and package.

• Thermal performance due to package needs to be included where appropriate

1mm gate width

Feedback Capacitance Feedback Capacitance -- CCGDGD

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 10 20 30 40 50 60

Drain Voltage

Feedback Capacitance Cgd (pF)

• Feedback capacitance is a strong function of drain voltage

• Inclusion of this effect necessary to fit small-signal data

• Non-linearity changes harmonic generation from the model – effects efficiency and linearity predictions

• Output Capacitance CDS is linear – no voltage dependence (weak anyway)

Input Capacitance Input Capacitance -- CCGSGS

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0

Gate Voltage (V)

Input Capacitance Cgs (pF)

• Input capacitance is a strong function of gate voltage

• CGS is also a function of drain voltage, but this non-linearity is not included at present

• The gate-voltage non-linearity also effects model’s harmonic generation

GaN HEMT Model GaN HEMT Model -- SmallSmall--SignalSignal

• On-wafer S-parameters of 0.5 mm HEMT – 25OC baseplate

• Major challenge of modeling for high power circuits – scaling from reasonable test cell to large periphery output stages – successfully implemented for scaling factors >100:1

• Non-linear model fits small-signal parameters over a range of bias voltages

• All measurements performed using 1% duty cycle, 20µs pulsed bias to control thermal effects

ModelGmax

MeasuredGmax

measured

model

freq (1.000GHz to 14.00GHz)

a(1,1)

b(1,1)

b(2,2)

a(2,2)

1E101E9 2E10

15

20

25

10

30

freq, Hz

ag

bg

GaN HEMT Model GaN HEMT Model -- LargeLarge--SignalSignal

measured

model

• On-wafer load-pull of 0.5 mm HEMT

• Measured at 3.5 GHz, VDS=48V, Id~25%IDSS, 25OC chuck temperature

• PAE contours not used for modeling due to sensitivity to harmonic loading –PAE verified using hybrid amplifier measurements

Power Contour Levels:

36 dBm

35 dBm

34 dBm

Basic Thermal Features of High Voltage GaNBasic Thermal Features of High Voltage GaN

• 240 Watts CW RF from a 28.8mm HEMT operating at 50 volts drain voltage

• Assume 60% DC to RF conversion efficiency

• 160 watts dissipated heat

• Active chip area is 2.5 sq. mm so heat density is

> 40 kilowatts per square inch !

• Much emphasis on new amplifier architectures to improve drain efficiencies

Broadband Amplifier Performance Broadband Amplifier Performance

TradeTrade--Off Analysis Off Analysis -- BackgroundBackground

• Broadband (0.8 to 2.2 GHz) push-pull amplifier to provide 100 watts peak power

• Two GaN HEMT die in “Gemini”package

– HEMTs attached to composite material shims within Cu-Mo-Cu package

• Study drain efficiencies over the band and impact on thermal management

– Comparison of different matching approaches and termination impedances

Theta-jc is 1.1 deg C/watt

Basic Amplifier Basic Amplifier

• Different matching topologies

– Drain-to-Gate Feedback

– Lossy Match

– Multi-section reactive

– Lossy Match with Feedback

• Concentrate on Lossy Match case

Power=10

1 2

SUBCKTID=S3NET="GaN HEMT Die Model G3"

1 2

3

SUBCKTID=S2NET="OMN Lossy Match"

1 2

3

SUBCKTID=S1NET="IMN Lossy Match"

Xo Xn. . .

SWPVARID=SWP4VarName="Power"Values=stepped(10,40,.1)UnitType=None

ATTENID=U1R=50 OhmLOSS=3 dB

DCVSID=V2V=2.2 V

I_METERID=AMP1

DCVSID=V1V=28 V

PORT1P=1Z=50 OhmPwr=Power dBm

PORTP=2Z=50 Ohm

PORTP=3Z=50 Ohm

PORTP=2Z=50 Ohm

PORTP=1Z=50 Ohm

CAPID=C1C=2.271 pF

TLINID=TL8Z0=9.149 OhmEL=42.65 DegF0=1.5 GHz



CAPID=C8C=2.414 pF

CAPID=C7C=1.243 pF

DC

RFRF&DC

12

3

BIASTEEID=X1

Overall Schematic

Input Match Schematic

PORTP=3Z=50 Ohm

PORTP=2Z=50 Ohm

PORTP=1Z=50 Ohm




CAPID=C5C=0.6011 pF

CAPID=C4C=1.006 pF

DC

RFRF&DC

1 2

3

BIASTEEID=X1

Output Match Schematic

Simulated Amplifier PerformanceSimulated Amplifier Performance

Small Signal Gain

Output Power at P3dB and Drain Efficiency

POUT

Efficiency

Gain = 13.2 dB ± 0.8 dB

POUT = 46 to 59 wattsDrain Efficiency = 49 to 66%Worst Case Dissipated Heat is 54 watts(per transistor)

Thermal PerformanceThermal Performance

• Assuming TJ limit of 200OC,

maximum dissipated heat of 108 watts and theta-jc of 1.1 deg C/Watt leads to a maximum case temperature of 81 deg C

• The thermal characteristics of the die and the package are very important – The design requires a

composite material shim such as silver-diamond (theta jc=550 W/mK) mounted on a Super-CMC package flange (theta jc = 370 W/mK)

• Before full electrical design is completed broadband amplifiers require thermal design even with GaN HEMTs!

Pdiss

0

0.5

1

1.5

2

2.5

3

3.5

4

0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3

Frequency (GHz)

Pdiss (W/mm)

Pdiss LossyMatch

3.75 W/mm dissipated54 watts per transistor

Dissipated Power as a function of frequency

Comparison of Dissipated Power vs. Comparison of Dissipated Power vs.

Frequency for 4 Amplifier ApproachesFrequency for 4 Amplifier Approaches

• Large-Signal Modeling of Broadband Amplifiers invaluable in selecting optimum topology for both electrical and thermal performance

Pdiss

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3

Frequency (GHz)

Pdiss (W/mm)

PdissMultisection

Pdiss LossyMatch

Pdiss LM wFeedback

Pdiss MS wFeedback

Multi-section reactive

Lossy match with feedback

Lossy MatchFeedback

Drain Efficiency at Device Sat

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

0.000 0.500 1.000 1.500 2.000 2.500 3.000

Frequency (GHz)

Drain Efficiency (%)

Power out at Device Sat (W)

0.00

20.00

40.00

60.00

80.00

100.00

120.00

0.000 0.500 1.000 1.500 2.000 2.500 3.000

Frequency (GHz)

Psat (W)

Measured 0.5 to 2.5 GHz PushMeasured 0.5 to 2.5 GHz Push--Pull Pull

Amplifier PerformanceAmplifier Performance

25 to 50 ohm coupler

Full amplifier with

coupler insertion losses

Average Gain = 15 dB

Psat > 80 watts and

Drain Efficiencies > 45%

500 to 2700 MHz Amplifier 500 to 2700 MHz Amplifier

using Cree CGH40010Fusing Cree CGH40010F

CAPID=C1C=15.55 pF

CAPID=C2C=1.187 pF

CAPID=C3C=0.9191 pF

CAPID=C4C=1.096 pF

CAPID=C5C=8.513 pF

1

2

3

CGH40010F_r2ID=40010F1TNOM=105

DCVSID=V1V=2.05 V

DCVSID=V2V=28 V

INDID=L1L=200 nH

INDID=L2L=200 nH

I_METERID=AMP1

PIPADID=P1Z1=50 OhmZ2=50 OhmDB=2 dB

RESID=R1R=51 Ohm

RESID=R2R=0 Ohm

TLINID=TL1Z0=70.11 OhmEL=32.91 DegF0=3 GHz



PORT_PS1P=1Z=50 OhmPStart=-8 dBmPStop=32 dBmPStep=5 dB PORT

P=2Z=50 Ohm

Lossy Match

Simulated Performance of Simulated Performance of

500 to 2700 MHz GaN HEMT PA500 to 2700 MHz GaN HEMT PA

0.5 1 1.5 2 2.5 2.7

Frequency (GHz)

Small Signal S21 S11 and S22

-30

-20

-10

0

10

20

30

dB

p3

p2

p1

DB(|S(1,1)|)[X,2]500 to 2700 MHz Stage

DB(|S(2,1)|)[X,2]500 to 2700 MHz Stage

DB(|S(2,2)|)[X,2]500 to 2700 MHz Stage

p1: Pwr = -3 dBm

p2: Pwr = -3 dBm

p3: Pwr = -3 dBm

-8 2 12 22 32

Input Power (dBm)

POUT and Efficiency Vs Input Power

0

20

40

60

80

dBm and %

DCRF(PORT_ 2 )[ *, X]

Re a l Ci rc u i t

DB(PT (PORT_2 ))[ *,X] (d Bm )

5 0 0 to 2 70 0 M Hz Sta g e

DCRF(PORT_ 2 )[ *, X]

5 0 0 to 2 70 0 M Hz Sta g e

DB(PT (PORT_2 ))[ *,X]

Re a l Ci rc u i t

• Worst Case Heat Dissipation is 9 watts• Theta-jc of packaged transistor is 5 deg C/watt• Max. channel temperature at 85 deg C case is 130 deg C.

Measured Performance of Measured Performance of

500 to 2700 MHz GaN HEMT PA500 to 2700 MHz GaN HEMT PA

0.5 1 1.5 2 2.5 2.7

Frequency (GHz)

Simulated Vs Actual

-10

-5

0

5

10

15

20

dB

p6

p5

p4p3

p2

p1

p1: Pwr = -3 dBm p2: Pwr = -3 dBm p3: Pwr = -3 dBm

p4: Pwr = -3 dBm p5: Pwr = -3 dBm p6: Pwr = -3 dBm

Output Power

20

22

24

26

28

30

32

34

36

38

40

42

44

10 12 14 16 18 20 22 24 26 28 30 32 34

PIN (dBm)

POUT (dBm)

0.25 GHz

0.50 GHz

0.75 GHz

1.00 GHz

1.25 GHz

1.50 GHz

1.75 GHz

2.00 GHz

2.25 GHz

2.50 GHz

2.70 GHz

3.00 GHz

Saturated Output Power and Drain Efficiency

363840424446485052545658606264666870727476788082

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25

Frequency (GHz)

POUT (dBm) / Efficiency (%)

PSAT

EFFICIENCY @PSAT

• Excellent agreement betweensimulations and measurements

• Measured efficiencies between50 and 78% over the band

Efficiency

Power

Output Power vs. Frequency

Saturated Output Power and Efficiency

Simulated and measured

Linear WiMAX AmplifierLinear WiMAX Amplifier

Simulation versus Measured DataSimulation versus Measured Data

• 60 Watt, 2.3 to 2.8 GHz linear amplifier design

• Developed an accurate packaged transistor model using the Cree GaN HEMT scale-able die model

• Circuit developed to address Fixed and Mobile Access WiMAX applications such as

– 802.16-2004

– 802.16e

– WiBro

• The design targets were as follows:

– Average Output Power > 8W

– EVM < 2.5%

– Drain Efficiency > 25% (under WiMAX stimulus)

CAPID=C2C=0.06 pF

CAPID=C3C=0.06 pF

CAPID=CDpad1C=0.48 pF

MLINID=TL1W=250 milL=60 mil

MSUBEr=9.6H=20 milT=1.4 milRho=1Tand=0ErNom=9.6Name=Alum_pkg1

SRLID=RLD1R=0.007 OhmL=0.285 nH

CAPID=C1C=0.06 pF

CAPID=C4C=0.06 pF

CAPID=CDpad2C=0.48 pF

MLINID=TL2W=250 milL=60 mil

SRLID=RLD2R=0.007 OhmL=Lbond nH

CAPID=C5C=0.03 pF

1

2

3

GaNg28v2_r3ID=GaNv2sc1TNOM=25SC=20SCF=1.44RTH=2.7VDD=50

SRLID=RL1R=0.001 OhmL=0.015 nH

V_METERID=VM1

PORTP=5Z=50 Ohm

PORTP=6Z=50 Ohm

CGH27060F Packaged Device ModelCGH27060F Packaged Device Model

1

2

3

CGH40045F_r1ID=CGH27030TNOM=25

ID=CGH27060TNOM=25

Input Circuit ModelInput Circuit Model

PORTP=1Z=50 O hm

PORTP=2Z= 50 Ohm

1 2

3

SUBCK TID=S3NET="G ate Pad 3 Por t"

1 2

SUBCKTID=S4NE T="Input Launch_AS TUNED"

1

SUBCKTID=S8NET= "Input_S hunt_GND_03_21_071"

1 2

3

4 SUBCKTID=S5NET="Input Tank Junction_EM1"

1

SUBCKTID=S 2NET="Gate B ias Feed w ith T rans Line_02_06_06"

1 2

SUBCKTID=S1NET= "S tabil ity C ircuit_New"

MLINID=TL_S HW =20 milL=230 m il

MDLX1 2

MODcatc0603001ID=ATC_600S _C1C=0.85 pFMSUB=Sim_mode= 0Tolerance=1PADW =35 m il

MLE FID=OpenW=30 milL=93 m il

MSUBEr=3.66H=20 m ilT=1.4 m ilRho=1Tand=0.004ErNom=3.48Name=Rogers 1

M STEP$ID=TL1 5

MSTEP$ID=TL14

M LINID=T L1 3W =7 0 milL =200 m il

MLINID=TL12W =20 mi lL= 130 m il

M LINID=T L11W =7 0 milL =200 mi l MSTEP$

ID=TL10M STEP$ID=T L9

MSTEP$ID=TL8

MSU B

Er=3.66H= 20 m ilT=1.4 milRh o=1Tand=0.004ErNom=3.66Na me=Roge rs 1

MLINID=T L4W =44 milL=565 m il

M LINID =T L2W =1 0 milL =120 mi l

MLI NID=TL1W =44 mi lL= 25 m il

PORTP=2Z=50 Ohm

PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

1

2

3

SUBCKTID=S1NET="Induct ive L ine_2p5_New1"

MLINID=T L1W=35 m ilL=23 m il

1

2

3

SUBCKTID=S2NET=" Induc tive Line_2p5_New1"

MDLX1 2

MODcatc 0603001ID=ATC _600S_C1C=2.2 pFMSUB=Sim _m ode=0Tolerance=1PADW =35 mil

PORTP=1Z =50 Ohm

MDLX

1 2

SU BCKTID=S3NET="Resis tor_100_Ohm Center1"

M STEP$ID=TL8

MLINID=TL5W=44 milL=25 m il

MLINID=TL4W =10 milL=40 mil

MLINID=T L3W=10 m ilL=40 m il

MSUBE r=3.66H =20 milT =1.4 milR ho=1T and=0.004E rNom=3.66N ame=R ogers 1

MLINID=TL2W =35 milL=23 mil

2

13

Output Circuit ModelOutput Circuit Model

M L INID = T L3

W =W o ut m i lL = L o ut m i l

ML IN

ID= T L 2W =W o u t mi l

L =5 0 m il

M BEND 90 X

ID= M S4W =Wo u t mi l

M =0 .5

M L IN

ID = TL 1 7W = 48 m ilL = 1 2 mi l

ML IN

ID = T L1 5W= 70 m i l

L=2 0 0 m i l

M STEP$ID= TL 1 4

M STEP$

ID= TL 1 3

M STEP$ID =TL 1 2

M STEP$

ID =TL 4

M LIN

ID= Db i a sL 3W=W b i a s m i l

L = Lb i a s m i l

M BEN D9 0 X

ID = MS6W =W b ia s mi l

M = 0 .5

ML IN

ID = Db i as L 2W=W b ia s mi l

L= L b i as m il

M BEN D9 0 XID = MS1W =W b ia s mi l

M = 0 .5

ML INID = Db i as L 1

W =Wb ia s mi lL= 2 4 0 m i l ML IN

ID = T L1 1W= 70 m i l

L= 2 0 0 m i l

M LIN

ID= T L 1 0W= 2 0 mi l

L = 1 30 m il

M LIN

ID= T L 1W= 4 4 mi l

L =1 44 m il

M LINID= T L 8

W =W o u t mi lL = 45 m i l

M L INID= T L 7

W =W o u t m ilL = L ou t m il

M LIN

ID= T L 5W =W o u t mi l

L = 44 m il

1

SU BCKT

ID= S1NE T= " Dra in Bi a s T e rm i na ti o n"

1

SUBC KTID= S5

NET = "D rai n B ias T e rm in a t io n "

ML EFID = OStu b 2W = 11 0 m il

L= 3 0 mi l

M L EF

ID= O Stu b6W = 7 2 mi l

L = 2 6 m i l

1

SU BCKTID= S6

NE T =" Ha rmo n i c As s is t_ AS T UN ED"

1 2

3

4SU BCKTID =S 2N ET= "Dra i n P ad 4 Po rt_2 p 5 "

M L EF

ID= O Stu b1W = 1 1 0 mi l

L = 3 0 m i l

M LIN

ID= T L 2 0W = 1 1 0 m i l

L = 2 m i l

MS TE P$

ID= TL 19M L IN

ID =T L 1 6W =1 6 0 mi l

L = 2 6 5 m i l

M DL X1 2

M OD ca tc 10 0 B0 0 1ID= ATC _1 0 0 B_ C1

C= 8 .2 pFM SUB=

Sim _m o d e= 0To l era n c e= 1

PAD W = 1 10 m il

M L EFID= O Stu b5W= 7 2 mi l

L = 2 6 m i l

1

2

3

4

M CR OSS$ID =T L 1 8

M SUBEr=3 .6 6

H =2 0 m ilT =1 .4 m i l

R ho = 1T a n d =0 .0 0 4ErN o m= 3 .4 8

N am e = Ro g ers 4 3 50

M BEND 90 XID= M S3

W =W o u t mi lM = 0.5

M BEND 90 X

ID= M S2W =W o u t mi l

M = 0.5

M L EFID =O Stu b 4

W =4 0 m ilL = 1 7 4 m i l

1

2

3

4

M CR OSS$ID =T L 9

M LIN

ID= T L 6W = 3 4 mi l

L = 60 m il

M L EFID =O Stu b 3

W =4 0 m ilL =1 7 4 m i l

ML INID= Db i a sL

W =W b i as m ilL =2 4 0 mi l

1 2

SUBC KTID= S3

NET = "D rai n B l o ck Ca p Pa d_ 2 p 5 "1

2

3SU BCKTID= S7

NE T= " 3p o rt_ co rn e r"

PO RTP=1Z =5 0 O hm

P ORT

P = 2Z = 5 0 Oh m

L stu b _ M= 7 0

Wo u t= 34

W d l in e = 1 00

L o ut= 6 1

L b ia s = 25 5W b i as = 4 0

L stu b _ A= 50

1

2

3

4

Fully Modeled Layout of AmplifierFully Modeled Layout of Amplifier

J3

LC

9 478 56 3 2 1

J2

J1

Actual Printed Circuit Board

Simulated and Measured AmplifierSimulated and Measured Amplifier

1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2

Frequency (GHz)

Small Signal Frequency Response

5

6

7

8

9

10

11

12

13

14

15

Small Signal G

ain (dB)

-15

-13

-11

-9

-7

-5

-3

-1

1

3

5

Return Loss (dB)

DB(|S(1,1)|) (R)Amp_SS_AsTuned

DB(|S(2,1)|) (L)Amp_SS_AsTuned

DB(|S(2,1)|) (L)fixt20_G28V2144L1w3__5

DB(|S(1,1)|) (R)fixt20_G28V2144L1w3__5

DB(|S(2,2)|) (R)Amp_SS_AsTuned

Simulated Linearity of AmplifierSimulated Linearity of Amplifier

26 28 30 32 34 36 38 40 42 44 46

2 Tone Average Output Power (dBm)

2-Tone IMD vs Average Ouput Power

-60

-50

-40

-30

-20

-10

0

3rd & 5th Order IMD (dBc)

0

10

20

30

40

50

60


IM3L_Pave (L)

IM3U_Pave (L)

IM5L_Pave (L)

IM5U_Pave (L)

DE_Pave (R)

Measured Linearity of AmplifierMeasured Linearity of Amplifier

EVM and Efficiency vs. Average Output Power

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 38.0 40.0 42.0

Average Output Power (dBm)

EVM (%)

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%


EVM 2.5GHz

DE 2.5GHz

Measured Linearity of AmplifierMeasured Linearity of Amplifier

EVM and Efficiency vs Frequency

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

2.300 2.400 2.500 2.600 2.700

Frequency (GHz)

EVM (%)

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%


EVM @ 26dBm

EVM @ 39dBm

Efficiency @ 2.5% EVM

Future GaN HEMT Future GaN HEMT

Model ImprovementsModel Improvements

• Behavioral models to allow direct simulation of various digital waveforms

• Improved active and passive switch models

• Improved models for switch mode PA’s

• Additional noise models

• Support for simulators other than ADS and MWO

Conclusions

• Successful development of GaN HEMT

large-signal models

• Models are scale-able over > 100:1 gate width ratio

• Models

– Are broadband

– Accurately predict DC, s-parameters, dynamic load lines, non-linearities

– Include self-heating

– Can be used in a range of amplifier types

• Demonstrated a variety of hybrid circuit applications

• Equally useful for MMIC amplifier designs

• Future extensions to include other features such as noise

App of NonLinear Models for GaN HEMT PA Design

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