Application of Non-Linear Models in a range of

WMC: Challenges in Model-Based HPA Design
Application of Non-Linear Models in a
range of challenging GaN HEMT Power
Amplifier Designs
Ray Pengelly, Brad Millon, Don Farrell,
Bill Pribble and Simon Wood
Cree Inc., Research Triangle Park, NC 27709
Outline
• Attributes of GaN HEMTs
• Cree GaN HEMT Models
• Design Examples
– Broadband CW Amplifiers
– Linear WiMAX Amplifier
• Future Model Improvements
• Conclusions
Attributes of GaN HEMTs
• 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
p
a
g
d
n
• High Efficiency
a
B
e
• Low Quiescent Current
Wid
• High Native Linearity
• Low capacitance per peak watt (12% of LDMOS and 21% of
GaAs MESFET) – supports broad bandwidths
• Enable new amplifier architectures
• Highly correctable under DPD
• Almost constant CDS as a function of VDS – great for Drain
Modulation
Models for GaN HEMTs
• 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 Schematic
pncap3
X15
sc=sc
scf=scf
cg1=cgd pF
cg2=0.6
cg3=0.1
vgg0=-21 V
R
R3
R=0.01 Ohm
SDD6P
SDD6P1
I[1,0]=(vg)/5e8
I[2,0]=id1
I[3,0]=(_v3)*gdsc
I[4,0]=(_v4)*gmc
I[5,0]=-vd*idt
I[6,0]=(vdf)/5e4
C[1]=
Cport[1]=
vg1
SRL
SRL1
R=(rg/sc+rg1/(sc*scf)) Ohm
L=(lg/sc+lg1/(scf*sc)) nH
Port
P1
Num=1
R
R5
R=1e6 Ohm
pncap3
X12
sc=sc
scf=scf
cg1=cgs pF
cg2=cg2
cg3=cg3
vgg0=vgg0 V
R
R1
R=(ri/(sc*scf)) Ohm
Drain current
SRL
SRL4
R=(rd/(sc*scf)) Ohm
L=(ld/sc+ld1/(sc*scf)) nH
C
C7
C=1.0 uF
Port
P2
Num=2
C
C9
C=(cds*sc*scf) pF
VCVS
SRC1
G=1
Port
P4
Num=4
Port
P5
Num=5
SRL
SRL3
R=(rs/(sc*scf)) Ohm
L=(ls/sc) nH
R
R6
R=1e6 Ohm
Thermal resistance
vd1g
R
R2
R=rth Ohm
C
C8
C=30.0 nF
Port
P8
Num=8
• 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”
More details on GaN HEMT Model
• Most FET models implement a gate
current-control characteristic that
transitions from the sub-threshold
Quad Linear
Compression
region to the linear gate control
Sub
region directly, without treating the Threshold
intermediate region, called the
Ids, mA
gm and Ids
Gm, mS
500
quadratic region. Fager et al.
implemented an equation and new
parameters to fit the quadratic
region. This leads to better
250
agreement with measured IMD and
other nonlinear characteristics.
• Gate charge is partitioned into gate- 0 -4
-3
-2
-1
0
0.5
Gate voltage, volts
source and gate-drain charge. Each
charge expression is a function of
Blue is DC transconductance
both VDS and VGS. Using charge
Red is drain current
partitioning, it is possible to fit most
GaN HEMT capacitance functions
and observed charge conservation.
30
4000
25
3333
20
2667
15
2000
10
1333
|S(2,1)|[1,X] (L)
Schematic 1
5
666.7
IDC(I_METER.AMP1) (R, mA)
Schematic 1
p1: Freq = 0.05 GHz
p1
0
-15
-10
-5
Voltage (V)
0
5
8
0
More details on GaN HEMT Model
•
•
•
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.
Drain Current Model
0.15
0.5
gm
permute(Is_high.i)
0.10
0.05
0.00
-4
-3
-2
-1
Vlow
0
1
2
0.4
0.3
0.2
0.1
0.0
0
5
10
15
20
25
30
35
40
Vhigh
•
•
•
•
•
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
45
Temperature Dependence – Self-heating
output power
36.5
36
35.5
35
34.5
34
0
1mm gate width
50
100
150
200
chuck temp
• 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
Feedback Capacitance Cgd (pF)
Feedback Capacitance - CGD
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
0
10
20
30
40
50
60
Drain Voltage
• 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 Cgs (pF)
Input Capacitance - CGS
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
Gate Voltage (V)
• 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 - Small-Signal
measured
30
model
20
a(2,2)
b(2,2)
b(1,1)
a(1,1)
bg
ag
Measured Gmax
Model Gmax
25
15
10
1E9
1E10
2E10
freq, Hz
freq (1.000GHz to 14.00GHz)
•
•
•
•
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
GaN HEMT Model - Large-Signal
Power Contour Levels:
36 dBm
35 dBm
34 dBm
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
Basic 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
Trade-Off Analysis - Background
• 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
•
•
Different matching topologies
– Drain-to-Gate Feedback
– Lossy Match
– Multi-section reactive
– Lossy Match with Feedback
PORT
P=1
Z=50 Ohm
TLIN
ID=TL6
Z0=43.09 Ohm
EL=195.3 Deg
F0=1.5 GHz
TLIN
ID=TL7
Z0=28.29 Ohm
EL=57.64 Deg
F0=1.5 GHz
TLIN
ID=TL8
Z0=9.149 Ohm
EL=42.65 Deg
F0=1.5 GHz
PORT
P=3
Z=50 Ohm
3
DC
RF
2
CAP
ID=C7
C=1.243 pF
DC
&
RF
BIASTEE
CAP
ID=X1
ID=C1
C=2.271 pF
CAP
ID=C8
C=2.414 pF
1
PORT
P=2
Z=50 Ohm
Concentrate on Lossy Match case
Input Match Schematic
DCVS
ID=V1
V=28 V
SWPVAR
ID=SWP4
VarName="Power"
Values=stepped(10,40,.1)
UnitType=None
Xo
. . . Xn
I_METER
ID=AMP1
ATTEN
ID=U1
R=50 Ohm
LOSS=3 dB
2
TLIN
ID=TL3
Z0=10.16 Ohm
EL=70.63 Deg
F0=1.5 GHz
TLIN
ID=TL4
CAP
Z0=18.75 Ohm
ID=C4
C=1.006 pFEL=86.31 Deg
F0=1.5 GHz
TLIN
ID=TL5
CAP
Z0=35.25 Ohm
ID=C5
C=0.6011 pF EL=93.57 Deg
F0=1.5 GHz
RF
2
PORT
P=2
Z=50 Ohm
BIASTEE
ID=X1
SUBCKT
ID=S1
NET="IMN Lossy Match"
1
3
DC
DC
&
1 RF
Power=10
PORT1
P=1
Z=50 Ohm
Pwr=Power dBm
PORT
P=3
Z=50 Ohm
PORT
P=1
Z=50 Ohm
3
1
2
1
3
SUBCKT
ID=S3
NET="GaN HEMT Die Model G3"
2
PORT
P=2
Z=50 Ohm
SUBCKT
ID=S2
NET="OMN Lossy Match"
DCVS
ID=V2
V=2.2 V
Output Match Schematic
Overall Schematic
Simulated Amplifier Performance
Output Power at P3dB and Drain Efficiency
Efficiency
Small Signal Gain
Gain = 13.2 dB ± 0.8 dB
POUT = 46 to 59 watts
Drain Efficiency = 49 to 66%
Worst Case Dissipated Heat is 54 watts
(per transistor)
POUT
Thermal Performance
•
3.75 W/mm dissipated
54 watts per transistor
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)
Pdiss
4
3.5
3
2.5
Pdiss (W/mm)
•
Pdiss Lossy
Match
2
1.5
1
0.5
•
Before full electrical design is
completed broadband amplifiers
require thermal design even
with GaN HEMTs!
0
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
2.1
2.3
Frequency (GHz)
Dissipated Power as a function of frequency
Comparison of Dissipated Power vs.
Frequency for 4 Amplifier Approaches
Lossy match with feedback
Pdiss
4.5
Multi-section reactive
4
3.5
Pdiss
Multisection
Pdiss(W/mm)
3
Pdiss Lossy
Match
2.5
Pdiss LM w
Feedback
2
Pdiss MS w
Feedback
1.5
1
Feedback
Lossy Match
0.5
0
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
2.1
2.3
Frequency (GHz)
• Large-Signal Modeling of Broadband Amplifiers
invaluable in selecting optimum topology for both
electrical and thermal performance
Measured 0.5 to 2.5 GHz Push-Pull
Amplifier Performance
25 to 50 ohm coupler
Drain Efficiency at Device Sat
70.00
60.00
Drain Efficiency (%)
50.00
Power out at Device Sat (W)
120.00
40.00
30.00
20.00
100.00
10.00
80.00
Psat (W)
0.00
0.000
0.500
1.000
1.500
2.000
Frequency (GHz)
60.00
40.00
20.00
0.00
0.000
0.500
1.000
1.500
Frequency (GHz)
2.000
2.500
3.000
Full amplifier with
coupler insertion losses
Average Gain = 15 dB
Psat > 80 watts and
Drain Efficiencies > 45%
2.500
3.000
500 to 2700 MHz Amplifier
using Cree CGH40010F
DCVS
ID=V2
V=28 V
I_METER
ID=AMP1
DCVS
ID=V1
V=2.05 V
Lossy Match
IND
ID=L2
L=200 nH
IND
ID=L1
L=200 nH
PORT_PS1
P=1
Z=50 Ohm
PStart=-8 dBm
PStop=32 dBm
PStep=5 dB
CAP
ID=C5
C=8.513 pF
TLIN
ID=TL3
Z0=53.79 Ohm
EL=26.09 Deg
F0=3 GHz
TLIN
ID=TL2
Z0=12.22 Ohm
EL=21.88 Deg
F0=3 GHz
TLIN
ID=TL1
Z0=70.11 Ohm
EL=32.91 Deg
F0=3 GHz
RES
ID=R1
R=51 Ohm
RES
ID=R2
R=0 Ohm
2
CAP
ID=C3
C=0.9191 pF
1
PIPAD
ID=P1
Z1=50 Ohm
Z2=50 Ohm
DB=2 dB
CAP
ID=C4
C=1.096 pF
CAP
ID=C2
C=1.187 pF
CAP
ID=C1
C=15.55 pF
3
CGH40010F_r2
ID=40010F1
TNOM=105
PORT
P=2
Z=50 Ohm
Simulated Performance of
500 to 2700 MHz GaN HEMT PA
Small Signal S21 S11 and S22
30
POUT and Efficiency Vs Input Power
80
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
20
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
p2
60
0
p3
p1
-10
DB(|S(1,1)|)[X,2]
500 to 2700 MHz Stage
DB(|S(2,1)|)[X,2]
500 to 2700 MHz Stage
-20
DB(|S(2,2)|)[X,2]
500 to 2700 MHz Stage
dBm and %
dB
10
40
20
p1: Pwr = -3 dBm
p2: Pwr = -3 dBm
p3: Pwr = -3 dBm
-30
0.5
1
1.5
Frequency (GHz)
2
2.5
2.7
0
-8
2
12
Input Power (dBm)
• 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.
22
32
Measured Performance of
500 to 2700 MHz GaN HEMT PA
• Excellent agreement between
simulations and measurements
• Measured efficiencies between
50 and 78% over the band
Output Power
Output Power vs. Frequency
44
0.25 GHz
40
0.50 GHz
0.75 GHz
38
1.00 GHz
P OUT (dBm)
36
Simulated
andVs
measured
Simulated
Actual
20
42
1.25 GHz
34
1.50 GHz
32
1.75 GHz
30
2.00 GHz
28
2.25 GHz
26
2.50 GHz
24
2.70 GHz
22
3.00 GHz
20
10
15
14
16
18
20
22
24
26
28
30
32
34
PIN (dBm)
10
Saturated Output Power and Drain Efficiency
Saturated
Output Power and Efficiency
5
0
-5
p1
p4
p3
p6
-10
0.5
1
1.5
Frequency (GHz)
2
2.5
2.7
p1: Pwr = -3 dBm p2: Pwr = -3 dBm p3: Pwr = -3 dBm
p4: Pwr = -3 dBm p5: Pwr = -3 dBm p6: Pwr = -3 dBm
P OUT (dBm) / Efficiency (%)
dB
12
p5
p2
82
80
78
76
74
72
70
68
66
64
62
60
58
56
54
52
50
48
46
44
42
40
38
36
Efficiency
Power
0
0.25
0.5
0.75
1
1.25
1.5
1.75
Frequency (GHz)
2
2.25
2.5
2.75
3
3.25
PSAT
EFFICIENCY @PSAT
Linear WiMAX Amplifier
Simulation 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)
CGH27060F Packaged Device Model
CG H40045F_r1
ID=CGH27060
ID=CG H27030
TNOM=25
TNOM=25
2
1
CAP
ID=C5
C=0.03 pF
3
MLIN
ID=TL1
W=250 mil
L=60mil
GaNg28v2_r3
ID=GaNv2sc1
TNOM=25
SC=20
SCF=1.44
RTH=2.7
VDD=50
SRL
ID=RLD1
R=0.007Ohm
L=0.285 nH
SRL
ID=RLD2
R=0.007 Ohm
L=Lbond nH
2
V_METER
ID=VM1
1
PORT
P=5
Z=50 Ohm
CAP
ID=C2
C=0.06pF
MSUB
Er=9.6
H=20 mil
T=1.4 mil
Rho=1
Tand=0
ErNom=9.6
Name=Alum_pkg1
CAP
ID=C3
C=0.06 pF
CAP
I D=CDpad1
C=0. 48 pF
MLIN
ID=TL2
W=250 mil
L=60 mil
CAP
ID=C1
C=0.06pF
CAP
ID=CDpad2
C=0.48 pF
3
SRL
ID=RL1
R=0.001Ohm
L=0.015nH
CAP
ID=C4
C=0.06pF
PORT
P=6
Z=50Ohm
Input Circuit Model
ML IN
ID=T L1
W =3 5 m il
L=2 3 m il
SU BCK T
ID=S 3
NE T="Re sis to r_ 10 0 _ Oh m Ce nt e r1"
M LI N
I D=TL2
W =3 5 mil
L =2 3 mil
MD L X
1
P O RT
P =1
Z =50 Oh m
MLIN
ID=TL 5
W =4 4 mil
L=2 5 m il
ML IN
ID=T L3
W=1 0 m il
L=4 0 m il
M ST EP $
I D=TL 8
2
1
1
S UB CK T
ID=S 2
NE T=" In du c tive Lin e _ 2p 5 _ Ne w1 "
3
3
2
2
MS UB
E r=3 .6 6
H =20 mil
T =1. 4 mil
R ho =1
T an d =0 .0 0 4
E rNo m=3 .6 6
N am e=R og e rs 1
1
MD L X
SU BC KT
ID=S 1
NE T="In d u ct ive L in e_ 2p 5_ Ne w1"
ML IN
ID=TL 4
W =1 0 mil
L =4 0 mil
P OR T
P =2
Z=5 0 O h m
SU BC KT
ID =S 2
N ET ="Gate B ias F eed w ith T rans Line_02 _06_06"
2
MO Dca tc 06 0 3 0 01
ID=A TC _60 0 S_ C1
C=2.2 p F
MS UB =
Sim _m od e =0
To lera n ce =1
PA DW =3 5 mil
MLE F
ID= Open
W = 30 m il
L=9 3 m il
M OD catc 06 03001
ID =AT C_6 00S _C 1
C =0.85 pF
M SU B=
Sim _m ode= 0
Tol era nc e=1
PAD W =35 m il
SU BCK T
ID= S4
NE T="Input La unc h_AS T UN ED "
1
3
1
2
1
2
3
1
2
1
MD LX
2
1
PO R T
P= 1
Z =5 0 O hm
PO R T
P= 1
Z=5 0 O hm
M LIN
I D=T L1 3
W =7 0 mil
L =200 m il
MSTE P$
ID =TL14
MLIN
ID =TL12
W =20 mi l
L= 130 m il
M LIN
I D=T L11
W =7 0 mil
L =200 mi l
MSTE P$
ID =TL10
M STEP $
I D=T L9
M STEP $
I D= TL1 5
MSU B
Er= 3.66
H= 20 m il
T= 1.4 mil
Rh o=1
Ta nd= 0.004
ErN om =3.66
Na me= Roge rs 1
SU BC KT
ID =S1
NE T= "S ta bil ity C irc uit_N ew"
M LIN
ID =T L2
W =1 0 mil
L =120 mi l
MLI N
ID =TL1
W =44 mi l
L= 25 m il
M STE P$
ID =TL8
MLIN
ID =T L4
W =44 mil
L= 565 m il
P O RT
P =2
Z= 50 O hm
M SU B
Er =3.66
H =20 m il
T =1.4 m il
R ho=1
T a nd=0.004
Er N om =3.48
N am e=R oge rs 1
4
2
POR T
P=2
Z= 50 Ohm
S UB CKT
ID = S5
N ET ="Input T ank J unctio n_EM 1 "
S UB CK T
I D= S3
N ET ="G ate Pad 3 Por t"
M LIN
ID =TL_S H
W =20 m il
L=2 30 m il
2
1
3
SU BC KT
ID =S8
N ET= "Input_S hunt_GN D _03_21_ 071"
1
Output Circuit Model
3
1
4
2
ML I N
ID = Db i as L 2
W=Wba
i s mi l
L= L b i as m li
M B END 90 X
I D= M S 4
W = W o u t mi l
M =0 . 5
S UB C K T
I D= S 5
NET = "D rai n B i as T e rm n
i a to
i n"
M B E ND 90 X
I D= M S 3
W = W o u t mi l
M = 0. 5
1
M B E N D9 0 X
ID = MS 1
W =Wba
i s mi l
M = 0 .5
M L EF
I D= O S t u b1
W = 1 1 0 mi l
L =3 0 m il
ML I N
ID = Db i as L 1
W=Wba
i s mi l
L= 2 4 0 m i l
P O RT
P=1
Z = 5 0 O hm
L st u b _ A = 50
W o u t = 34
L o ut = 6 1
L st u b _ M= 7 0
Wd ln
i e = 1 00
W b i as = 4 0
Lb a
i s = 25 5
ML E F
ID = OS t u b 2
W = 11 0 m li
L= 3 0 mi l
M L IN
I D = T L3
W = W o ut m i l
L = L o ut m i l
S UB C K T
I D= S 3
NE T = "D rai n B l o ck Ca p P a d_ 2 p 5 "
3
M DL X
1
S U BCK T
I D =S 2
N E T = "Dra i n P ad 4 P o rt _2 p 5 "
2
4
1
M L IN
I D =T L 1 6
W =1 6 0 mi l
L =2 6 5 m il
MS TE P $
I D= T L 19
M LI N
I D= T L 2 0
W =1 1 0 m il
L =2 m il
ML I N
I D= Db i a sL
W = W b i as m li
L =2 4 0 mi l
M B E N D9 0 X
ID = MS 6
W =Wba
i s mi l
M = 0 .5
2
1
2
M OD ca t c 10 0 B0 0 1
I D= A T C _1 0 0 B_ C1
C= 8 . 2 pF
M S UB =
Si m _m o d e= 0
T o l era n c e= 1
PA D W = 1 10 m li
ML I N
I D= T L 2
W = W o u t mi l
L =5 0 m li
1
SU B CK T
I D= S 1
NE T= " Dra n
i Bi a s T e rm i na ti o n"
M B E ND 90 X
I D= M S 2
W = W o u t mi l
M = 0. 5
M L EF
I D =O S t u b 4
M L IN
I D= T L 7
W = W o u t m li
L = L ou t m li
M L EF
I D= O S t u b6
W = 7 2 mi l
L =2 6 m il
W =4 0 m li
L =1 7 4 m il
1
M CR OS S$
I D =T L 9
M LI N
I D= T L 6
W = 3 4 mi l
L = 60 m li
2
R ho = 1
T a n d =0 . 0 0 4
E rN o m= 3 . 4 8
N am e = Ro g ers 4 3 50
M STEP$
I D= T L 1 3
M LI N
I D= T L 1
W = 4 4 mi l
L = 1 44 m li
2
3
1
S U B CKT
I D= S 7
NE T= " 3p o rt _ co rn e r"
1
ML I N
ID = T L1 5
W = 70 m i l
L= 2 0 0 m i l
M LI N
I D= T L 1 0
W = 2 0 mi l
L = 1 30 m li
M STEP$
I D =T L 4
ML I N
ID = T L1 1
W = 70 m i l
L= 2 0 0 m i l
3
3
2
1
M LI N
I D= T L 8
W = W o u t mi l
L = 45 m i l
M L IN
I D = TL 1 7
W = 48 m li
L = 1 2 mi l
4
M L EF
I D =O S t u b 3
W =4 0 m li
L =1 7 4 m il
M SUB
E r= 3 . 6 6
H =2 0 m li
T =1 .4 m i l
M LI N
ID= Db i a sL 3
W = W b i a s m il
L = Lb i a s m i l
M LI N
I D= T L 5
W = W o u t mi l
L = 44 m li
S U B CK T
I D= S 6
NE T =" Ha rmo n i c A s s s
i t _ A S T UN ED"
M CR OS S $
4 I D =T L 1 8
M L EF
I D= O S t u b5
W = 7 2 mi l
L=2 6 m il
M STEP$
I D =T L 1 2
M STEP$
I D= T L 1 4
P ORT
P =2
Z = 5 0 Oh m
Fully Modeled Layout of Amplifier
1
J
9 8 7 6 5 4 3 2 1
L
C
3
J
2
J
Actual Printed Circuit Board
Simulated and Measured Amplifier
5
14
3
13
1
12
-1
11
-3
10
-5
DB(|S(1,1)|) (R)
Amp_SS_AsTuned
9
DB(|S(2,1)|) (L)
Amp_SS_AsTuned
8
DB(|S(2,1)|) (L)
fixt20_G28V2144L1w3__5
7
DB(|S(1,1)|) (R)
fixt20_G28V2144L1w3__5
6
DB(|S(2,2)|) (R)
Amp_SS_AsTuned
5
1.8 1.9
2
2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9
Frequency (GHz)
3
3.1 3.2
-7
-9
-11
-13
-15
Return Loss (dB)
Small Signal Gain (dB)
Small Signal Frequency Response
15
Simulated Linearity of Amplifier
2-Tone IMD vs Average Ouput Power
60
IM3L_Pave (L)
IM3U_Pave (L)
-10
50
IM5L_Pave (L)
IM5U_Pave (L)
-20
40
DE_Pave (R)
-30
30
-40
20
-50
10
-60
0
26
28
30
32
34
36
38
40
42
2 Tone Average Output Power (dBm)
44
46
Drain Efficiency (%)
3rd & 5th Order IMD (dBc)
0
Measured Linearity of Amplifier
EVM and Efficiency vs. Average Output Power
EVM (%)
3.50
40.0%
EVM 2.5GHz
DE 2.5GHz
35.0%
3.00
30.0%
2.50
25.0%
2.00
20.0%
1.50
15.0%
1.00
10.0%
0.50
5.0%
0.00
22.0
24.0
26.0
28.0
30.0
32.0
34.0
36.0
Average Output Power (dBm)
38.0
40.0
0.0%
42.0
Drain Efficiency (%)
4.00
Measured Linearity of Amplifier
EVM and Efficiency vs Frequency
4.00
40.0%
EVM @ 26dBm
3.50
35.0%
EVM @ 39dBm
3.00
30.0%
2.50
25.0%
2.00
20.0%
1.50
15.0%
1.00
10.0%
0.50
5.0%
0.00
2.300
2.400
2.500
Frequency (GHz)
2.600
0.0%
2.700
Drain Efficiency (%)
EVM (%)
Efficiency @ 2.5% EVM
Future GaN HEMT
Model 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