W-band InP/InGaAs/InP DHBT MMIC Power Amplifiers
Yun Wei, Sangmin Lee, Sundararajan Krishnan, Mattias Dahlström, Miguel Urteaga, Mark Rodwell
Department of Electrical and Computer Engineering, University of California
[email protected] tel: 805-893-8044, fax 805-893-3262
W-band MIMIC Power AmplifiersIMS2002
Y.C.Chen et. Al. IPRM, May 19992-stage 94 GHz W-band HEMT power amplifier0.15 m composite-channel InP HEMT Imax=750mA, VBR=7V, Pout= 316 mW
J. Guthrie et. Al, IPRM, May 2000Cascode 78 GHz HBT power amplifiertransferred substrate InGaAs/InAlAs SHBT Imax=100mA, VBR=2.5V, Pout= 12 mW
This work single stage W-band HBT power amplifierstransferred substrate InP/InGaAs/InP DHBT Imax=128mA, VBR=7V, Pout= 40 mWHighest reported power for W-band HBT power amplifier
HBT processing
•Normal emitter and base processing no collector contact
• polyimide isolation, SiN insulation, interconnection metals (M1 and M2), Benzocyclobutene planarization, thermal via and ground plane plating
•Flip chip bounding to carrier
•Substrate etching
•Schottky contact collector
simultaneous scaling of emitter and collector widths
Wiring environment
•Micro strip transmission line BCB dielectric, r=2.7, t=5 m
•MIM capacitorsBCB bypass capacitor, SiN capacitor (r=7, t=0.4 m )
•NiCr resistor R�=40/ �
Low via inductance, reduced fringing fields, increased conductor losses
Transferred-Substrate HBT MMIC technology
cbbbCRff 8/max
MBE DHBT layer structure
Band profile at Vbe=0.7 V, Vce=1.5 V
emitter
InGaAs 1E19 Si 500 Å
Grade 1E19 Si 200 Å
InP 1E19 Si 900 Å
InP 8E17 Si 300 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
0
10
20
30
40
1 10 100 1000
Gai
ns (
dB)
Frequency (GHz)
U
h21 462
395
343
139
0.5 m Transferred-Substrate DHBT UCSBSangmin Lee
0.0
1.0
2.0
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, f = 139 GHz
Vce(sat) ~1 V at 1.8 mA/m2
Multi-finger DHBTs: Design Challenges UCSBARO
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
Self-aligned base contact thickness=0.08 mbase 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
Thermal instability (current hogging) in multi-finger DHBTs:
Distributed base feed resistance:
ondistributicurrent uniform ensure to1/
factor Stability
Eballastex
ceJAbe
qIkTRR
V
dT
dVK
Ic
Temperature
Large Current High Breakdown Voltage Broadband InP DHBT
UCSBARO MURI
8-finger device8 x ( 1 m x 16 m emitter )8 x ( 2 m x 20 m collector )
7 m emitter spacing
~8 Ohm ballast per emitter finger
fmax>330 GHz,
Vbrceo>7 V, Jmax>1x105 A/cm2
2nd-level base feed metal
Ballast resistor
emitter
collector
Flip chip
UCSBInP TS DHBT Power Amplifier Design
ARO MURI
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)
Imax
Vsat VCE_BR
• Designed using large signal model derived from DC-50 and 75-110 GHz measurements of previous generation devices
• Output tuning network loads the HBT in the optimum admittance for saturated output power
• Shunt R-C network at output provides low frequency stabilization
• Electromagnetic simulator (Agilent’s Momentum) was used to characterize passive elements
Low frequency stabilization
Optimum admittance match
Input match
W band 128 m2 power amplifier UCSB
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
f0=85 GHz, BW3dB=28 GHz,GT=8.5 dB, P1dB=14.5 dBm, Psat=16dBm
Bias: Ic=78 mA, Vce=3.6 V
W band 64 m2 power amplifier UCSB
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
f0=90 GHz, BW3dB=20 GHz, GT=8.2 dB, P1dB=9.5 dBm, Psat=12.5 dBm
Bias condition: Ic=40 mA, Vce_CB=3.5 V, Vce_CE=1.5 V
bias
Conclusions
• Wideband Power DHBT: Ic= 100 mA, Vce=3.6 V, fmax=330 GHzthermal design and base feed design critical for wide bandwidth
• Power DHBT large signal modeling
• Wideband Power amplifiers: f0=85 GHz, BW3dB=28 GHz,GT=8.5 dB, Psat=16dBm
Future work
• Higher power DHBTs: lumped 4-finger topology and longer emitter finger
• Multi-stage wideband power amplifiers
• ~200 GHz power amplifiers
Acknowledgement
Work funded by ARO-MURI program under contract number PC249806.
UCSBIMS2002