A High-Gain, Low-Noise, +6dBm PA in 90nm CMOS for 60-GHz

Radio

Mehdi Khanpour+, Sorin Voinigescu+, M. T. Yang*+University of Toronto, *TSMC

October 2007

Compound Semiconductor IC Symposium

October 2007 Mehdi Khanpour 2

Outline

• Motivation

• 60-GHz Radio

• PA schematic

• Fabrication

• Measurement results

• Conclusion

October 2007 Mehdi Khanpour 3

Motivation

• 60-GHz Band (57-64 GHz)– Large bandwidth and limited propagation– High data rate (4+Gbps), short range– Personal Area Networks, Wireless HDTV

• CMOS alternative – lower power – higher integration and lower cost

October 2007 Mehdi Khanpour 4

60-GHz Radio

• Simple narrow-band radio architecture

• Implemented in 90nm CMOS– Receiver w/o VCO [1] – Up-converter [2]– Power Amplifier (this

work)

PLL

VCO

IFLNA

BUF

BUF

BUF

56-61 GHz

52.2-57.5 GHz

32

2 GHz

Reference

3.5-5.5 GHz

PA

56-61 GHz

3.5-5.5 GHzIF

October 2007 Mehdi Khanpour 5

PA Schematic

• Input designed as LNA with inductive feedback• Input matched by LG and LS

• Output designed as PA with source degeneration for linearitySGSTIN RRLfZ 2}{

October 2007 Mehdi Khanpour 6

PA Design

• Stage 1 biased at 0.2 mA/μm and sized for simultaneous noise and input impedance matching

• Stage 2 and 3 biased at 0.3 mA/μm for linearity

• Output stage sized for PSAT = 6.5 dBm with Inductive degeneration for linearity

• Inductors and interconnects modeled using ASITIC

October 2007 Mehdi Khanpour 7

Fabrication

• Fabricated in TSMC 90nm GP CMOS• 9-layer Cu back-end, no “thick” metal

67GHz Cable

110GHz Cable

67GHz Infinity Probes

50GHz Bias T

300μm× 500μm

Large signal test setup:

October 2007 Mehdi Khanpour 8

Simulations

• 18 dB Gain, 4.5 dB NF• Γopt, S11 and S22 < -10 dB from 50-68 GHz

October 2007 Mehdi Khanpour 9

Measurement vs. Simulation

• 14 dB Gain, 3dB bandwidth extends from 48-61 GHz• S11 and S22 < -10 dB from 48-65 GHz

October 2007 Mehdi Khanpour 10

Measurement vs. Simulation

• Measurement shows 14 dB gain @ 55 GHz

• Diffusion region in layout is wider than the minimum allowed by design kit

• Extra capacitance pushing the centre frequency down is not captured in simulations

56601

/1

MIN

D

WW

LCf

October 2007 Mehdi Khanpour 11

Measurement vs. Simulation

• S21 peaks at 55 GHz when extra capacitance is added

October 2007 Mehdi Khanpour 12

S-Parameters Across 5 Dies

• Results show excellent repeatability

October 2007 Mehdi Khanpour 13

S21 vs. Power Supply

• 2 dB drop in gain from 1.5V to 1.2V supply

October 2007 Mehdi Khanpour 14

Linearity Measurement

• 6 dBm PSAT, 1.6 dBm P1dB

• Maximum PAE is 6% @ 55 GHz and 5.2% @ 60 GHz, η = 22%

October 2007 Mehdi Khanpour 15

Linearity vs. Current Density

• Optimal linearity bias coincides with peak fT current density of 0.3~0.35 mA/μm

October 2007 Mehdi Khanpour 16

Temperature Measurements

• Gain decreases by 5 dB and PSAT by 2 dBm from 25oC to 100oC

October 2007 Mehdi Khanpour 17

Scaling

• Same concept implemented in 65nm at 80 GHz• Third stage is cascode with identical size (40 μm)• Higher gain but lower PSAT due to cascode output stage, η = 11%

October 2007 Mehdi Khanpour 18

PA Comparison

PA Technology

f G PSAT P1dB,out PAE Area Topology FoM

170 GHz fMAX 90nm

CMOS

60 GHz

14 dB 6 dBm 1.6 dBm 6% 0.3×0.5mm2 2-stage cascode + CS

10

170 GHz fMAX 90nm CMOS [3]

60 GHz

5.2 dB 9.3 dBm 6.4 dBm 7.4% 0.35×0.43mm2 3-stage CS 7.5

200/290 GHz fT/fMAX

SiGe HBT [4]

60 GHz

10.8dB 16 dBm 11.2 dBm 4.3% 2.1×0.8mm2 2-stage CE 73

200/290 GHz fT/fMAX

SiGe HBT [5]

77 GHz

19dB 14 dBm 12 dBm 15.7%

NA cascode + 2-stage CE

444

2fPAEGPFoM SAT

October 2007 Mehdi Khanpour 19

Conclusion

• 60-GHz PA with 14 dB gain demonstrated in 90nm CMOS

• PA characterized over process, supply voltage and temperature variation

• Results show excellent yield and repeatability

• Scalable to 80 GHz in 65nm CMOS

October 2007 Mehdi Khanpour 20

Acknowledgment

• Jaro Pristupa and CMC for CAD tools and support

• OIT and CFI for equipment grants

• TSMC for facilitating the technology access

October 2007 Mehdi Khanpour 21

References

[1] D. Alldred et al, CSICS 2006

[2] S. P. Voinigescu et al, ISCAS 2007

[3] T. Yao et al. RFIC-Symp 2006

[4] B. Floyd et al, ISSCC 2004

[5] S. T. Nicolson et al, IMS 2007