A Current-Switching Phase Shifter forMillimeter-Wave Applications

Chien M. TA, Efstratios SKAFIDAS, and Robin J. EVANS

National ICT Australia (NICTA)Department of Electrical and Electronic Engineering

The University of Melbourne

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 2

Outline

• Introduction to 60-GHz wireless communications– Phased-array antennae

• Phase shifter design

• Results

• Conclusions

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 3

60 GHz wireless communications

• Unlicensed band– 7GHz of bandwidth– Multi-Gbps wireless communications

• High path loss

– 88dB free-space loss at 60GHz and 10m distance– Additional attenuation due to oxygen absorption– Phased-array antenna system

• Low cost– CMOS technology

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 4

Steerable antenna system

Transmitter: focus output power

Receiver: improve SNR, reject interferers

Variable delay line (or phase shifter)

x(t-0)

x(t-τ)

x(t-2τ)

x(t-(N-1)τ)Transmit beam

Variable delay line (or phase shifter)

x(t-0)

x(t-τ)

x(t-2τ)

x(t-(N-1)τ)

Receive beam

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 5

Array factor

λ/2

x

y

z

θ

φ

b4

b3

b2

b1

Beam β1 β2 β3 Β4

1 0° 180° 0° 180°

2 0° 270° 90° 0°

3 0° 270° 180° 90°

4 0° 270° 270° 180°

5 0° 0° 0° 0°

6 0° 90° 90° 180°

7 0° 90° 180° 270°

8 0° 90° 270° 0°

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 6

Published 60-GHz phase shifters

• [Alalusi CICC 2006]– Vector modulator– Pros: 360° phase control– Cons: high power consumption (~72mW)

• [Wu EuMIC 2007]– Vector modulator– Pros: continuous, 360° phase control– Cons: lossy (more than 17dB)

• [Ta CCECE 2008]– Distributed– Pros: negligible power consumption– Cons: lossy, narrow phase control range

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 7

Proposed phase shifter architecture

50 Ω

Input

Output

S000S090S180S270

gmvinvinTransconductance device

λ/4, 50 Ω λ/4, 50 Ω λ/4, 50 Ω

• Discrete phases determined by length of transmission line• Current switching mode

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 8

Schematic

50 Ω

Input

Output

M1M2M3M4

l = 600 µmZ0 = 50 Ω

M0

Rbias

l = 600 µmZ0 = 50 Ω

l = 600 µmZ0 = 50 Ω

VDD

Vbias

Rg3

V180

Rg2

V090

Rg1

V000

Rg4

V270S4 S3 S2 S1

P4 P3 P2 P1

LP

LS

LM

Cin

Cout

Cbypass

• M0: input transconductance, sized and biased for high gain and low noise

• M1-4: switches

• V000, V090, V180, V270: digital input for phase control

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 9

Layout

• 65-nm RF-CMOS

• Microstrip lines

• MIM capacitors

• 525μm × 470μm

Input Output

VDD

GND

Transconductance device, M0

M4

M3 M2

M1

S1

S2S3

S4

P1P2P3P4

LP

LS LM

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 10

Simulation results

90°

90°

90°

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 11

Simulation results (cont’d)

Frequency band 57 GHz to 66 GHz

Power supply 1.5 V

Power consumption 9 mW

Output phase 0°, 90°, 180°, 270°

Power loss < 3 dB

Input return loss < −6 .7 dB

Output return loss < −10 dB

Noise figure 4.3 to 6.1 dB

IIP3 1.2 dBm

June 29, 2009 NEWCAS-TAISA 2009, Toulouse, France 12

Conclusions and future works

• Active phase shifter on CMOS– 57 to 66 GHz– 90°-step output phase– Low noise– Digitally controlled

• Experimental works– Chip is under fabrication– Phase shifter measurement– Antenna array measurement

A Current-Switching Phase Shifter forMillimeter-Wave Applications

TA, Chien M., SKAFIDAS, Efstratios, and EVANS, Robin J.

National ICT Australia (NICTA) Department of Electrical and Electronic Engineering

The University of Melbourne