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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
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OutlineLEC 2002 UCSB
• Introduction• Transferred-Substrate Power DHBT Technology• Circuit Design• Results• Conclusion
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Introduction LEC 2002
• 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
• This Work:
Single stage cascode InP DHBT, class A, Pout=50 mW, Gain=7 dB, PAE=12.5% size=0.42 mm2
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Transferred-Substrate HBT MMIC fabrication
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MBE DHBT layer structure
Band profile at Vbe=0.7 V, Vce=1.5 V
InP 8E17 Si 300 Å
emitter
InGaAs 1E19 Si 500 Å
Grade 1E19 Si 200 Å
InP 1E19 Si 900 Å
Grade 8E17 Si 233 Å
Grade 2E18 Be 67 Å
InGaAs 4E19 Be 400 Å
Grade 1E16 Si 480 Å
InP 2E18 Si 20 Å
InP 1E16 Si 2500 Å
Multiple stop etch layers
Buffer layer 2500 Å
base collector
substrate
400 Å InGaAs base3000 Å InP collector
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0
10
20
30
40
1 10 100 1000
Gai
ns (
dB)
Frequency (GHz)
U
h21 462
395
343
139
Small-area T.S. DHBTs have high cutoff frequencies.
UCSBSangmin Lee
0.0
1.0
2.0
3.0
0 1 2 3 4 5 6 7 8 9
Vce(V)
Ic(m
A)
BVCEO = 8 V at JE =0.4 mA/m2
fmax = 462 GHz, ft = 139 GHz
Vce(sat) ~1 V at 1.8 mA/m2
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Design difficulties with large-area power DHBTs UCSBYun Wei
ARO MURI
Thermal instability further increasescurrent non-uniformity
Ic
Temperature
collector
SiNemitter
contactbase poly
BCBBCB Metal strip
Au Via
Steady state current and temperature distribution when thermally stable
base feed sheet resistance:
s= 0.3 / �significant for > 8 um emitter finger length
Large Area HBTs: big Ccb, small Rbb,
even small excess Rbb
substantially reduces fmax
0.08 m
Emitter contactMetal1
Base contact
Current hogging in multi-finger DHBT:
Distributed base feed resistance:
Ic
Temperature
K<1 for thermal stability→ must add emitter ballast resistance
Initial current and temperature distribution
thermal feedback further increases current non-uniformity
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8 finger common emitter DHBTEmitter size: 16 um x 1 um Ballast resistor (design):9 Ohm/finger
0
20
40
60
80
100
120
0 1 2 3 4 5
I c, m
A
Vce
, Volts
Ibstep = 380 A
0
5
10
15
20
25
0 1 2 3 4 5 6
I c, m
A
Vce
, Volts
Ibstep = 300 A
0
5
10
15
20
25
1010 1011
Ga
ins,
dB
Frequency, Hz
H21
U
fmax
=120 GHz
f=91 GHz
Jc=5e4 A/cm2
Vce=1.5 V
First Attempt at Multi-finger DHBTs: Poor Performance Due to Thermal Instability
thermally driven current instability collapse
UCSB
low fmax due to premature Kirk effect (current hogging) excess base feed resistance
ARO MURI
Yun Wei
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Large Current High Breakdown Voltage Broadband InP DHBT
UCSB
8 -finger DHBT8 x (1 m x 16 m emitter )8 x (2 m x 20 m collector )
Key Improvements8 Ohm ballast per emitter finger2nd-level base feed metal
Device Performancefmax>330 GHz, Vbrceo>7 V,Jmax>1x105 A/cm2
100 mA, 3.6 Volt device
2nd-level base feed metal
Ballast resistor
emitter
collector
Flip chip
Yun Wei
ARO MURI
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UCSBHBT power amplifier-why cascode?
ARO MURI
Yun Wei
IB1
* R. Ramachandran and A.F. Podell "Segmented cascode HBT for microwave-frequency power amplifiers"
Advantages:common-base stage has large Vce
→ large output power common-emitter-stage has low Vce
→ small Rballast required
→ maintains large available power gain
Disadvantageinductance of base bypass capacitoreven small L greatly degrades gain
Vce1
Vce2
+-+
-IE1
Rballast
IE2
radial stub capacitor
common basestage mesa
common emitterstage mesa
bias 2 bias 3
bias 1
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UCSBInP TS DHBT Power Amplifier Design
ARO MURI
Yun Wei
Optimum admittance match
Input match
Low frequency stabilization
4 parallel cascode amplifier
4 parallel cascode amplifier
8 finger cascodeInter-stage
DC bias
/4
/4
Imax
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
Vce (V)
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
Ic (
A)
VCE_BRVsat
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40 GHz 128 m2 power amplifier UCSB
cascode PA
0.6mm x 0.7 mm, AE=128 m2
ARO MURI
f0=40 GHz
BW3dB=16 GHz
GT=7 dB
P1dB=14 dBm
Psat=17 dBm @ 4dB gain
-40
-30
-20
-10
0
10
20 25 30 35 40 45
Sij,
dB
Frequency, GHz
S21
S11
S22
-5
0
5
10
15
20
0
2
4
6
8
10
12
14
-15 -10 -5 0 5 10 15
Po
ut,
GT,
dB
m
PA
E, %
Pin, dBm
GT
Pout
PAE
Yun Wei
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UCSBYun Wei
common base PA
-5
0
5
10
15
20
0
2
4
6
8
10
-15 -10 -5 0 5 10 15
Po
ut,
dB
m GT , d
B
Pin, dBm
GT Pout
-30
-25
-20
-15
-10
-5
0
5
10
80 90 100 110
S11
, S
21,
S22
frequency, GHz
S21
S22
S11
0.5mm x 0.4 mm, AE=128 m2
ARO MURI
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
Y. Wei et al, 2002 IEEE MTT-S symposium
W band power amplifiers in TS InP DHBT technology
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W band power amplifiers in TS InP DHBT technology
UCSBYun Wei
cascode PA
0.5mm x 0.4 mm, AE=64 m2
ARO MURI
-5
0
5
10
15
0
2
4
6
8
10
-15 -10 -5 0 5 10
Po
ut, d
Bm G
T , dB
Pin, dBm
GT Pout
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
Y. Wei et al, 2002 IEEE MTT-S symposium
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Continuing work
Higher-current DHBTs for increased mm-wave output power250 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 amplifiersdesigns for > 100 mW saturated output power now being tested
Results to be reported subsequently…
UCSB
Yun WeiLEC 2002
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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 WeiLEC 2002