A 0.7 V-to-1.0 V 10.1 dBm-to-13.2 dBm 60-GHz Power ... · A 0.7 V-to-1.0 V 10.1 dBm-to-13.2 dBm 60-GHz Power Amplifier Using Digitally-Assisted LDO Considering HCI Issues Rui Wu,

A 0.7 V-to-1.0 V 10.1 dBm-to-13.2 dBm

60-GHz Power Amplifier Using Digitally-

Assisted LDO Considering HCI Issues

Rui Wu, Yuuki Tsukui, Ryo Minami, Kenichi Okada,

and Akira Matsuzawa

Tokyo Institute of Technology, Japan

1

Outline

• Background

– 60-GHz field is attractive

• Hot-Carrier-Induced Issues

– HCI influence on circuit reliability

• Variable-Supply-Voltage PA using

Digitally-assisted LDO

– Circuit design & Measurement results

• Conclusions

2

Background

[1] http://www.tele.soumu.go.jp

• 9-GHz unlicensed bandwidth

• Several Gbps wireless communication

e.g. IEEE 802.15.3c

QPSK3.5 Gbps/ch

16QAM7 Gbps/ch

3

HCI Issues are Emerging at 60 GHz

High fmax, suitable for

60-GHz amplifier

Bad HCI performance

60-GHz power amplifier

Standard

Good HCI performance

Low fmax, can’t be used

for 60-GHz amplifier

2.4-GHz power amplifier

Thick oxide

Standard

4

Hot-Carrier-Induced (HCI) Effects

P-Substrate

Impact ionization

n+n+Oxide

damage

Gate

Source Drain

Isub

Iｇ

SiO2

Degrade Vth, gm, drain current, and lifetime

5

1E+00

1E+02

1E+04

1E+06

1E+08

1E+10

0.4 0.5 0.6 0.7 0.8 0.9

65 nm NMOSFET DC Stress Lifetime

1/VDS (1/V)

100

102

104

106

108

1010

Lif

eti

me t

(s

)

[2] E. Takeda et al., IEDL 1983

VGS

VDS

VDS

t

V

Stress condition

VGS = 0.8 V

Lifetime is the time drain current decreases by 10%

6

1

10

100

1E+02 1E+03 1E+04 1E+05

65 nm NMOSFET RF Stress Lifetime ∆

I DS

at (%

)

Freq.=100 MHz,

Po=11 dBm

102 103 104 105

Time (s)

[3] L. Negre et al., JSSC 2012

Vgs

Vds

Stress condition

t

0.8 V

1.2 V

Vds Vgs

7

Hot-Carrier Damage Mechanism [4]

• Single Vibrational Excitation (SVE) is related to

high energetic carrier that has enough energy to

break Si-H bond; (High energy)

• Electron Electron Scattering (EES) is caused by

one carrier promotes the other into higher energy

and allows Si-H breaking; (Medium energy)

• Multiple Vibrational Excitation (MVE) is due to a

series of low energetic carriers that accumulate

enough energy to break Si-H bond. (Low energy)

[4] C. Guerin et al., JAP 2009

8

Hot-Carrier Physical Model [3]

IDS(t) is the time-varying drain current which is a function

of VGS(t) and VDS(t);

K and a are damage mode dependent constants;

m and n are process-related constants.

[3] L. Negre et al., JSSC 2012

9

Conventional Solutions

[6] M. Tanomura et al., ISSCC 2008

[5] A. Siligaris et al., JSSC 2010

[7] J. Chen et al., ISSCC 2011

Better lifetime

Degraded output power,

efficiency, and linearity

Cascode [5]

Low Vdd [6]

Better lifetime, output

power, and linearity

Sensitive to process

variations

Power combining [7]

10

Application Scenario

◆Single Carrier (SC) Mode of IEEE 802.15.3c

MCS identifier 8 1

Data rate 2640 Mb/s 412 Mb/s

Rx sensitivity -56 dBm -61 dBm

Required CNR 17.5 dB 12.5 dB

Distance 0.56 m 1 m 1 m

Required Pout 5 dBm 10 dBm 5 dBm

Mod 1+MCS 8

0 d0.56 m 1 m

Mod 1+MCS 1

&

Mod 2+MCS 8

*NF=8 dB; Thermal noise=-81.5 dBm; Antenna gain=2 dBi;

Implementation loss=-2 dB; freq.=60 GHz

Mod1 low power

Mod2 high power

11

Lifetime estimation

12

Time-Division Duplex (TDD) Operation

SIFS SIFSRX

TX TXACK

...

...

Time

Time

In IEEE 802.11ad, short inter-frame space (SIFS)

is indicated to be 3ms

• TDD operation can eliminate the

stringent requirement of filtering and

extend the available bandwidth for

transceivers.

13

The Proposed Power Amplifier

14

Transient Operation of the LDO

VPA

Time

βVref

VrefD

Training

βV’ref

V’refD

Sleep

RecordRestore

Awaking Awaking

Restore

Record

15

Transient Simulation Result

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 1 2 3 4

0.1 ms

Time (ms)

VP

A (

V)

CLK=200 MHz

CL=86 pF

16

Differential PA Topology

Vdd VPAVddVg1 Vg2 Vg3

M1M2

M3

M4 M5 M6

RFin+

RFin-

RFout-

RFout+

Cc1 Cc2

Cc1 Cc2

MIM TL TL

The cross-coupling capacitor technique is adopted

to improve the stability and power gain

17

Die Micro-photograph

PA

LDOCL

700 m

m

800 mm

18

Measured Small-Signal S-parameter

19

PA Performance vs VPA @60 GHz

5

10

15

20

25

30

0

3

6

9

12

15

0.7 0.8 0.9 1.0

Ps

at a

nd

P1d

B (

dB

m)

VPA (V)

PA

Em

ax (

%)

P1dB

Psat

PAEmax

20

0.01

0.1

1

10

100

1.E+001.E+021.E+041.E+061.E+081.E+10

Measured Lifetime of the PA ∆

I DS

at (%

)

Time (s)

VPA=1.00 V, Pout=10 dBm



1 102 104 106 108 1010

21

Measured Output Spectrum

-50

-40

-30

-20

-10

0

-2.5 -1.5 -0.5 0.5 1.5 2.5Centered Freq. (GHz)

Mag

nit

ud

e (

dB

)

-50

-40

-30

-20

-10

0

-2.5 -1.5 -0.5 0.5 1.5 2.5M

ag

nit

ud

e (

dB

) Centered Freq. (GHz)

(a)

IEEE 802.15.3c Spectrum mask

(b)

Spectrum centered at 62.64 GHz for QPSK modulation

(a) VPA=1.0 V, Pout=4 dBm; (b) VPA=0.7 V, Pout=3 dBm

22

Measured EVM for QPSK Modualtion

-20

-19

-18

-17

-16

-15

0.7 0.8 0.9 1

Pout = 5 dBm

Pout = 7 dBm

Pout = 10 dBm

VPA (V)

EV

M (

dB

)

23

60 GHz CMOS PA Performance Comparison

† Only for the last stage VPA

[6] M. Tanomura et. al, ISSCC 2008

[7] J. Chen et. al, ISSCC 2011

[5] A. Siligaris et. al, JSSC 2010

Ref. Process Vdd

(V)

P1dB

(dBm)

Psat

(dBm)

PAEmax

(%)

Lifetime

(year)

[5] 65 nm

SOI

1.2 7.1 10.5 22.3

N/A 1.8 12.7 14.5 25.7

2.6 15.2 16.5 18.2

[6] 90 nm 0.7 5.2 8.5 7.0 > 105*

1.0 10.5 11.5 8.5 > 10*

[7] 65 nm 1.0 15.0 18.6 15.1 N/A

[8] 65 nm 1.0 8.0 11.5 15.2 > 10*

This

work 65 nm

0.7† 5.8 10.1 8.1 > 102

1.0† 10.2 13.2 15.0 > 0.2

[8] W. L. Chan et. al, JSSC 2010

* Non-measured results

24

Conclusions

– The lifetime of the proposed PA can be improved

dramatically by dynamic operation.

– The tunable supply offers a possibility to meet

different linearity, efficiency, output power and

lifetime requirements in actual applications.

– The PA is insensitive to the process variations

thanks to the tunable supply voltage.

25

Thank you for your attention!

26

27

Output Power Distribution [5]


28

Transistor Measurement Data

[9] Q. Bu et. al, SSDM 2012

0

5

10

15

20

25

30

35

0 20 40 60 80 100

MA

G (

dB

)

Frequency (GHz)

CS

Cascode

29

Power Consumption

VPA IDigital IAnalog IPA

1.0 V 64 mA 312 mA 130 mA

0.7 V 64 mA 312 mA 120 mA

30

Lifetime Improvement of the PA

t1

t

t2 t3 tdtd-1

A1(t)1/n

A(t)1/n

A2(t)1/n

A3(t)1/n

Ad(t)1/n

Af(t)1/n

Fixed

Dynamic

Age function

31

The Flow Chart of Dynamic Operation

Sleep mode?

Bias on

Control frame

received?

Bias and output

power change

Yes

No

Yes

No

Bia

s a

nd

ou

tpu

t

po

we

r m

ain

tain

Bias off

32

Spectrum Measurement Setup

PA

AWG

PowerMeter

ParameterAnalyzer

ATT ATT

SpectrumAnalyzer

SignalGenerator

60-GHz TX Board

33

EVM Measurement Setup

PA 60-GHz RX Board

AWG Osci.

PowerMeter

ParameterAnalyzer

ATT ATT60-GHz TX Board

34

Dynamic Comparator Schematic [9]

Vi+ Vi-

Vb

ClkDi- Di+

Di- Di+

Vo+ Vo-

Vdd Vdd

[9] M. Miyahara et. al, ASSCC 2008

(a) First stage (b) Second stage

35

36

65 nm NMOSFET DC Stress Lifetime

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

1E+10

0.4 0.5 0.6 0.7 0.8 0.9

VGS=0.8 V

1/VDS (1/V)

VDS=1.2 V

VDS=2.0 V

100

101

102

103

104

105

106

107

108

109

1010 L

ife

tim

e t

(s

)

[2] E. Takeda et al., IEDL 1983

37

65 nm NMOSFET RF Stress Lifetime

∆I D

Sa

t (%

) VDS=1.2 V, VGS=0.8 V

1

10

100

1E+02 1E+03 1E+04 1E+05

Freq.=100 MHz,

Pout=11 dBm

102 103 104 105

Time (s) [3] L. Negre et al., JSSC 2012

38

CMOS PA Performance Comparison





Ref. Process Freq.

(GHz)

Vdd

(V)

P1dB

(dBm)

Psat

(dBm)

PAEmax

(%)

[5] 65 nm

SOI 60

1.2 7.1 10.5 22.3

1.8 12.7 14.5 25.7

2.6 15.2 16.5 18.2

[6] 90 nm 60 0.7 5.2 8.5 7.0

1.0 10.5 11.5 8.5

[7] 65 nm 60 1.0 15.0 18.6 15.1

[8] 65 nm 60 1.0 8.0 11.5 15.2

This

work 65 nm 60

0.7† 5.8 10.1 8.1

1.0† 10.2 13.2 15.0


39

CMOS PA Performance Comparison





Ref. Process Vdd

(V)

P1dB

(dBm)

Psat

(dBm)

PAEmax

(%)

Lifetime

(year)

[5] 65 nm

SOI

1.2 7.1 10.5 22.3

N/A 1.8 12.7 14.5 25.7

2.6 15.2 16.5 18.2

[6] 90 nm 0.7 5.2 8.5 7.0 > 105*

1.0 10.5 11.5 8.5 > 10*

[7] 65 nm 1.0 15.0 18.6 15.1 N/A

[8] 65 nm 1.0 8.0 11.5 15.2 > 10*

This

work 65 nm

0.7† 5.8 10.1 8.1 > 102

1.0† 10.2 13.2 15.0 > 0.2


* Estimation results

Documents

A 0.7 V-to-1.0 V 10.1 dBm-to-13.2 dBm 60-GHz Power ... · A 0.7 V-to-1.0 V 10.1 dBm-to-13.2 dBm 60-GHz Power Amplifier Using Digitally-Assisted LDO Considering HCI Issues Rui Wu,