1 2 3 4 5 6 7 8 90 10

-40

-35

-30

-25

-20

-15

-10

-5

-45

0

freq, GHz

dB

(S(2

,1))

Ma

xG

ain

1

Insertion loss, dB

A CMOS Power Amplifier for WCDMA/GSM Handset Applications

Bonhoon Koo and Songcheol Hong

School of EECS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701, Republic of Korea

E-mail : gsb0026@kaist.ac.kr

Output transformerSchematic

This work was supported by Samsung Electro-Mechanics in Korea

Motivation Power Stage

CMOS PA

+ High integration (easy to integrate with CMOS Tx)

+ Low cost (good to commercial products)

- Low linearity (due to large knee voltage)

- Low efficiency (due to lossy substrate)

- Low breakdown voltage

Multimode CMOS PA

• High linearity support various applications

• Broad band cover various band

• High efficiency increase battery life time

1.3 mm X 1.3 mm

In TSMC 0.18-㎛ process

Power Amplifier Symposium 2009

Cascode structure

• 0.18-m (CS) / 0.35-m (CG)

• Reduces voltage stress

VCG controls to change mode

• WCDMA(Linear) mode VCG = 2.1 V

• GSM(Saturation) mode VCG = 3.0 V

R-C Feedback

• Improves linearity

• Improves stability

2-stage CMOS PA

• All matching components

integrated without output

matching network

• Total gate width [m]

- MD1 : 768

- MD2 : 1,024

- MP1 : 3,072

- MP2 : 4,096

1.1 mm X 1.0 mm

Integrated Passive Device (IPD)

Characteristics of transformer

• IPD process

- High resistive Si substrate

- Thick metal

• Very symmetrical structure

- Reduce 2nd harmonic

• Broad band

• Filtering 3rd harmonic

• MAG : -0.59 dB / IL : -0.78 dB

@1.9GHz

1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.41.4 2.5

-1.2

-1.1

-1.0

-0.9

-0.8

-0.7

-0.6

-0.5

-1.3

-0.4

freq, GHz

dB

(S(2

,1))

Ma

xG

ain

1

Insertion loss, dB

MAG

IL

Simulated insertion loss(IL) and maximum available gain(MAG) of transformer

Conclusions

■ Two wireless communication standards (WCDMA & GSM) with a single CMOS PA

■ Improve linearity by feedback , biasing cascode and filtering 2nd harmonic in WCDMA mode

■ Improve Pout, PAE, harmonics by IPD transformer in GSM mode

Power Amplifier Symposium 2009

-50 -40 -30 -20 -10 0 10-20

-10

0

10

20

30

40

0

5

10

15

20

25

30

35

Po

PAE

Po

ut

[dB

m]

PA

E [

%]

Pin [dBm]

S-parameters (WCDMA mode)

Small signal gain : 26.3 dB (@1.95GHz)

3dB Bandwidth : 0.65 GHz (1.6 – 2.25 GHz)

S11 & S22 < -10dB (1.6 – 2.25 GHz)

1.0G 1.5G 2.0G 2.5G 3.0G-30

-20

-10

0

10

20

30

40

3dB Bandwidth

S-p

ara

me

ters

[d

B]

Frequency [Hz]

S22

S11

S21

Pout and PAE (WCDMA mode)

Frequency : 1.95 GHz

1 tone Input power sweep from – 41.3 to 6.7 dBm

P1dB : 30.6 dBm & PAE : 30.0 % (@P1dB)

ACLR (WCDMA mode)

Modulated signal - 3GPP WCDMA (1.95GHz)

Linear powerMAX(-33dBc @5MHz offset) :26.75 dBm

WCDMA Class3 requirement of Pout > 26 dBm

Pout and PAE (GSM mode)

15.0 17.5 20.0 22.5 25.0 27.5 30.0-60

-55

-50

-45

-40

-35

-30

-25

-60

-55

-50

-45

-40

-35

-30

-25

WCDMA Linearity Spec

AC

LR

[d

Bc

]

Pout [dBm]1600 1700 1800 1900 2000

31.0

31.5

32.0

35

40

45

PA

E [

%]

Po

ut

[dB

m]

Frequency [MHz]

Po

PAE

Input power :10dBm

Frequency sweep from 1600 to 2000 MHz

POUT > 31.6 dBm & PAE : > 38.0 % (GSM band)

Harmonics (GSM mode)

2nd Harmonic < -38.07 dBc (GSM band)

3rd Harmonic < -38.8 dBc (GSM band)

Performance summary

1600 1700 1800 1900 2000-45

-40

-35

Ha

rmn

on

ic [

dB

c]

Frequency [MHz]

2nd

3rd

WCDMA mode GSM mode

Frequency [GHz] 1.95 1.81

Gain [dB] 26 22

Po [dBm] 26.75 31.8

PAE [%] 19.5 42.2

Etc [dBc]ACLR : -33

@5 MHz offset

2nd harmonic : -42

3rd harmonic : -40