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

yunwei@ece.ucsb.edu 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