Transcript 40 GHz MMIC Power Amplifier in InP DHBT Technology Y.Wei, S.Krishnan, M.Urteaga, Z.Griffith, D.Scott, V.Paidi, N.Parthasarathy, M.Rodwell Department of Electrical and Computer Engineering, University of.

40 GHz MMIC Power Amplifier in InP DHBT
Technology
Y.Wei, S.Krishnan, M.Urteaga, Z.Griffith, D.Scott,
V.Paidi, N.Parthasarathy, M.Rodwell
Department of Electrical and Computer Engineering,
University of California
[email protected] tel: 805-893-8044, fax 805-893-3262
LEC 2002
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Outline
UCSB
Introduction
Transferred-Substrate Power DHBT Technology
Circuit Design
Results
Conclusion
LEC 2002
•
Introduction
Applications for power amplifiers in Ka band
 satellite communication systems
 wireless LANs
 local multipoint distribution system
 personal communications network links and digital radio
•
MMIC Amplifiers in this frequency band
Kwon et. al., IEEE MTT, Vol.48, No. 6, June. 2000
3 stage HEMT, class AB, Pout=1 W, Gain=15 dB, PAE=28.5%, size=9.5 mm2
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This Work:
Single stage cascode InP DHBT, class A, Pout=50 mW, Gain=7 dB,
PAE=12.5% size=0.42 mm2
Transferred-Substrate HBT MMIC fabrication
MBE DHBT layer structure
InGaAs 1E19 Si 500 Å
collector
substrate
Grade 1E16 Si 480 Å
InP 2E18 Si 20 Å
InP 1E16 Si 2500 Å
Multiple stop etch layers
Buffer layer 2500 Å
base
Grade 2E18 Be 67 Å
InGaAs 4E19 Be 400 Å
Band profile at Vbe=0.7 V, Vce=1.5 V
emitter
Grade 1E19 Si 200 Å
InP 1E19 Si 900 Å
InP 8E17 Si 300 Å
Grade 8E17 Si 233 Å
400 Å InGaAs base
3000 Å InP collector
Small-area T.S. DHBTs
have high cutoff frequencies.
40
Sangmin Lee
fmax = 462 GHz,
ft = 139 GHz
30
Gains (dB)
UCSB
U
20
343
395
10
h21
139
462
0
1
10
100
1000
Frequency (GHz)
BVCEO = 8 V at JE =0.4 mA/m2
Vce(sat) ~1 V at 1.8 mA/m2
6.0
3.0
5.0
2.0
Ic(mA)
Ic(mA)
4.0
3.0
2.0
1.0
1.0
0.0
0.0
0
0.5
1
1.5
Vce(V)
2
2.5
3
0
1
2
3
4
5
Vce(V)
6
7
8
9
ARO
MURI
Design difficulties with large-area power DHBTs
Assume init ial temperat re
u differenceT between 2 fingers
Current
dVbe hogging in multi-finger DHBT:
 1.1 mV/K at const antI c
dT
Ic
Ic
dV
1
T  Vbe  be T  I C 
Vbe
dT
Rex  Rballast  kT / qIE
Temperature
Temperature
UCSB
Yun Wei
contact
SiN
emitter
base
poly
collector
 P  VCE I C  T   JAP
BCB
Metal strip
BCB
Au Via
Initial
current
temperature
Steady
stateand
current
and temperature
distribution
distribution when thermally stable
Unst ableunless
K thermalstability 
Thermal instability further increases
current non-uniformity
thermal feedback further increases
current non-uniformity
dVbe
VCE JA
K<1 for thermal stability
1
dT Rex  Rballast  kT / qIE
→ must add emitter ballast resistance
Distributed base feed resistance:
base feed sheet resistance:
s= 0.3 /•
Metal1
Emitter contact
significant for > 8 um
emitter finger length
0.08 m
Base contact
Large Area HBTs:
big Ccb, small Rbb,
even small excess Rbb
substantially reduces fmax
ARO
MURI
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First Attempt at Multi-finger DHBTs:
Poor Performance Due to Thermal Instability
Yun Wei
thermally driven current instability  collapse
120
25
I , mA
100
c
80
b
15
10
60
5
40
0
c
I , mA
I step = 300 A
20
0
I step = 380 A
20
1
2
3
4
V , Volts
5
6
ce
b
0
0
1
2
3
V , Volts
4
5
ce
25
Jc=5e4 A/cm2
Vce=1.5 V
8 finger common emitter DHBT
Emitter size: 16 um x 1 um
Ballast resistor (design):9 Ohm/finger
low fmax due to
premature Kirk effect (current hogging)
excess base feed resistance
Gains, dB
20
U
15
H
21
10
f
=120 GHz
max
5
f =91 GHz

0
10
10
Frequency, Hz
10
11
ARO
MURI
UCSB
Large Current High Breakdown Voltage
Broadband InP DHBT
2nd-level base feed metal
8 -finger DHBT
8 x (1 m x 16 m emitter )
8 x (2 m x 20 m collector )
Yun Wei
emitter
Key Improvements
8 Ohm ballast per emitter finger
2nd-level base feed metal
Flip chip
Device Performance
fmax>330 GHz,
Vbrceo>7 V,
Jmax>1x105 A/cm2
100 mA, 3.6 Volt device
collector
Ballast resistor
30
140
A =128 um
120
25
U, MSG/MAG, dB
14
12
10
80
Ic, m A
Ic, mA
100
60
8
6
4
40
2
0
-1
20
AE=128um2
2
E
IC=100mA
20
15
Vcb=2.9V
MSG/MAG
U
10
5
0
1
2
3
4
5
6
fmax=330 GHz
7
Vcb, V
0
0
2
4
Vcb, V
6
8
10
0 0
10
10
1
10
2
Frequency, GHz
10
3
ARO
MURI
UCSB
HBT power amplifier-why cascode?
Advantages:
common-base stage has large Vce
→ large output power
common-emitter-stage has low Vce
→ small Rballast required
→ maintains large available power gain
bias 2
Disadvantage
inductance of base bypass capacitor
even small L greatly degrades gain
IB1
bias 1
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bias 3
common base
+
Vce2 IE2 stage mesa
+
common emitter
I
Vce1 E1 stage mesa
-
Rballast
radial stub capacitor
* R. Ramachandran and A.F. Podell "Segmented cascode HBT for microwave-frequency power amplifiers"
ARO
MURI
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InP TS DHBT Power Amplifier Design
Yun Wei
Imax
0.018
0.016
0.014
Ic (A)
0.012
0.010
0.008
0.006
0.004
0.002
Vsat
VCE_BR
0.000
4 parallel cascode amplifier
/4
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Vce (V)
Optimum admittance
match
/4
Input match
Low frequency
stabilization
4 parallel cascode amplifier
8 finger cascode
Inter-stage
DC bias
4.5
5.0
5.5
6.0
6.5
7.0
ARO
MURI
UCSB
40 GHz 128 m2 power amplifier
Yun Wei
cascode PA
f0=40 GHz
BW3dB=16 GHz
GT=7 dB
P1dB=14 dBm
Psat=17 dBm @ 4dB gain
0.6mm x 0.7 mm, AE=128 m2
14
20
10
S21
12
0
-10
S11
10
T
Sij, dB
S22
-20
-30
Pout
10
PAE
G
T
6
5
4
0
-40
20
25
30
35
Frequency, GHz
40
45
8
-5
-15
2
-10
-5
0
Pin, dBm
5
10
0
15
PAE, %
Pout, G , dBm
15
W band power amplifiers in TS InP
DHBT technology
ARO
MURI
UCSB
Yun Wei
common base PA
Bias: Ic=78 mA, Vce=3.6 V
f0=85 GHz
BW3dB=28 GHz
GT=8.5 dB
P1dB=14.5 dBm
Psat=16dBm, associated gain: 4.5 dB
0.5mm x 0.4 mm, AE=128 m2
20
10
10
S21
GT
5
8
10
6
5
4
0
2
S11
-15
T
-10
-20
-25
-30
80
90
100
110
frequency, GHz
Y. Wei et al, 2002 IEEE MTT-S symposium
G , dB
-5
Pout, dBm
S22
0
S11, S21, S22
Pout
15
-5
0
-15
-10
-5
0
Pin, dBm
5
10
15
W band power amplifiers in TS InP
DHBT technology
ARO
MURI
UCSB
Yun Wei
cascode PA
Bias: Ic=40 mA, Vce=3.5 V
f0=90 GHz
BW3dB=20 GHz
GT=8.2 dB
P1dB=9.5 dBm
Psat=12.5 dBm, associated gain: 4 dB
0.5mm x 0.4 mm, AE=64 m2
15
15
S21
GT
5
Pout
8
Pout, dBm
10
0
-5
S22
-10
-15
6
GT, dB
S11, S21, S22, dB
10
5
4
0
2
S11
-20
-25
10
80
90
100
110
frequency, GHz
Y. Wei et al, 2002 IEEE MTT-S symposium
-5
-15
-10
-5
0
Pin, dBm
5
0
10
LEC 2002
Continuing work
Higher-current DHBTs for increased mm-wave output power
250 GHz fmax, Ic,max=240 mA,
thermally stable at 200 mA bias at Vce=3.2 Volts
→ suitable for W-band ~150 mW power amplifiers
W-band DHBT power amplifiers
designs for > 100 mW saturated output power now being tested
Results to be reported subsequently…
UCSB
Yun Wei
LEC 2002
Conclusions
• 40 GHz MMIC power amplifier in InP DHBT technology
7 dB power gain and 14 dBm output power at 1 dB compression.
17 dBm (50 mW) saturated output power
12.5% peak power added efficiency
Future work: higher power DHBT power amplifiers at W-band and above
lumped 4-finger topology, longer emitter fingers, power combining
G-band (140-220 GHz) DHBT power amplifiers
Acknowledgement
Work funded by ARO-MURI program under contract number PC249806.
UCSB
Yun Wei