MICROWAVE AND RF Case Study: Amp5 Design of a WiMAX … · CA CB CC BONDWIRES BONDWIRES SOURCE ......

Case Study:Amp5Design of a WiMAX Power AmplifierPresented by Michael Steer

Reading:Chapter 19, Section 19.6 Based on material in Microwave and RF

Design: A Systems Approach, 2nd Edition, by Michael Steer. SciTech Publishing,

2013.Presentation copyright Michael Steer

MICROWAVE AND RF DESIGN

Index: CS_Amp5

Design of a WiMAX Power Amplifier

Slides copyright 2013 M. Steer.

3.4 to 3.8 GHz Power Amplifier

Output power at 1 dB gain compression is 28 dBm

2

WiMAX power amplifier

● Necessary to use nonlinear simulation, harmonic balance analysis preferred.

● Thermal heat-sinking is very important.● Must consider possible layout at the beginning.● Must have a topology in mind.● Specifications:

– 28 dBm output power– 3.4 to 3.8 GHz

3

Z = 50 0

PORT 1

InputMatchingNetwork

Z = 50 0

PORT 2

MatchingNetwork

Output

_

M 1 M 2

Input

Gate bias

1 2

Transistor

50 V

100 mA

Output

21

1.115 V

119 A

Drain bias

Amplifier

RF RF

Amplifier topology● High level topology:

● LinearClass ABamplifierloadline:

VDS

ID DC loadline

AC loadline

Quiescent point4

(Final bias voltages are shown)

3.4 to 3.8 GHz

Transistor selection

GATE

DRAIN

SOURCE

DIE

DIE

DIE

CACB

CC

BONDWIRES

BONDWIRES

SOURCE

BONDWIRES

2.1 GHz silicon LDMOS transistor.

5

Bias concept

VDS

I D(m

A)

VGS

1008060402000

300

600

700

500

400

200

100

(V)

0 V

-0.5 V

-1 V

-1.5 V

6Quiescent DC power = 5 W.

S11 and S22

11S

22S

(dB

)S

3.51.50.5 2.5 4.5 5.5

0

-5

-10

-15

-20

3.4 to 3.8 GHz operating frequency

Output33 // 4.4 pF2.5 –j11

Input almost 50 (with small parallel capacitance) 7

S21 and S123.4 to 3.8 GHz operating frequency

S21

S12

(dB

)S

-40

-20

0

20

40

1.50.5 2.5 3.5 4.5 5.5Frequency (GHz)

8

Design concept

INPUT

OUTPUT

9

Amplifier Layout

10Presentation copyright Michael SteerIndex: CS_Amp5B

Layout

OUTPUTINPUT

11

Input matching network

TRANSISTOR GATERF INPUT

GND

GND

DC BLOCK

CAPACITORS

500 RESISTOR

LINE WITH HIGH Z0

GATE BIAS

50 LINE

12

GND

Output matching network

TRANSISTOR DRAIN RF OUTPUT

GND

GND

DC BLOCK

CAPACITORS

LINE WITH HIGH Z0

DRAIN BIAS

50 LINE

(2.5 –j11

13


MTEEID=TL3

MSTEPID=TL25W1=1 mmW2=1.88 mm

MLINID=TL2W=1.88 mmL=3.55 mm

MLINID=TL1W=1.88 mmL=8 mm


CAPID=C2C=5.6 pF

500

PORTP=2Z=50 Ohm

MSUBEr=3.38H=0.8128 mmT=0.03556 mmRho=1.0Tand=0.002ErNom=3.38Name=SUB1


MSTEPID=TL24W1=1.156 mmW2=0.254 mm


MTEEID=TL12

MTEEID=TL5

MTEEID=TL9


VIAID=V1D=0.635 mmH=0.813 mmD=0.0356 mm



CAPID=C4C=10 nF







MTEEID=TL15



MLINID=TL18W=3 mmL=5 mm




PORTP=1Z=50 Ohm


CAPID=C3C=5.6 pF

CAP

C=1 nFID=C1

CAPID=C6C=1 uF

1.115 VGate DC bias voltage

RF input Active device

14

MTEEID=TL3





CAPID=C2C=5.6 pF

500

PORTP=2Z=50 Ohm



PORTP=1Z=50 Ohm



Input matching network (RF Path)

15

Input matching network (detail)

MTEEID=TL3





CAPID=C2C=5.6 pF

500

PORTP=2Z=50 Ohm





MTEEID=TL5



PORTP=1Z=50 Ohm


CAPID=C3C=5.6 pF


REST OF BIAS CIRCUIT 16


MTEEID=TL3





CAPID=C2C=5.6 pF

500

PORTP=2Z=50 Ohm





MTEEID=TL12

MTEEID=TL5

MTEEID=TL9





CAPID=C4C=10 nF







MTEEID=TL15







PORTP=1Z=50 Ohm


CAPID=C3C=5.6 pF

CAP

C=1 nFID=C1

CAPID=C6C=1 uF



17

MTEEID=TL10

MTEEID=TL18

MTEEID=TL16

MTEEID=TL17

MTEEID=TL6

PORTP=1Z=50 Ohm


MLINID=TL3W=3 mmL=5.7 mm

CAPID=C3C=5.6 pF

MSTEPID=TL9W1=10 mmW2=3 mm

PORTP=2Z=50 Ohm



CAPID=C1C=0.500 pF



CAPID=C2C=10 nF


MLINID=TL24W=1.2 mmL=1.5 m



CAPID=C6C=1 uF



CAPID=C4C=100 nF












MSTEPID=TL4W1=1 mmW2=10 mm

Drain DC bias voltage 50 V

RF OutputActive device

Output matching network

18

Amplifier Design

19Presentation copyright Michael SteerIndex: CS_Amp5C

Z = 50 0

PORT 1

InputMatchingNetwork

Z = 50 0

PORT 2

MatchingNetwork

Output

_

M 1 M 2

Input

Gate bias

1 2

Transistor

50 V

100 mA

Output

21

1.115 V

119 A

Drain bias

Amplifier

RF RF

Amplifier topology● Final bias voltages are shown.

● LinearClass ABamplifierloadline:

VDS

ID DC loadline

AC loadline

Quiescent point20

Poweramplfiier

Signalsource Automated

tunerActivedevice

Impedancetransformer Automated

tuner

Spectrumanalyzer

Highpowerattenuator

Powersensor

PowermeterPower

sensor

Powermeter

controllerInstrument

Load‐pull system

21

Load‐pull points

22

Poweramplfiier

Signalsource Automated

tuner

Z in

• At 3.5 GHz showing the reflection coefficient (here S11) looking into the output matching network and the contours of constant output power.

• POUT,MAX = 42.6 dBm. • Output power for the first

contour surrounding POUT,MAX is 42.5 dBm and the powers of the contours reduce in 0.5 dBmsteps.

• S11 of the final output matching network design is shown from 3.4 to 3.8 GHz

S11

Output POUT,MAX

Output load‐pull contour of POUT

23

POUT

50

40

30

20

10

013 33233

Gain

Gai

n (d

B)

or O

utpu

t pow

er (

dBm

)

Input power (dBm)

Output power and gain at 3.5 GHz

24

POUT

Drain efficiency

Gain

0

50%

40%

30%

20%

10%

Dra

in e

ffici

ency

0

10

20

30

40

50

10 20 25 30 32Input power (dBm)

15

Gai

n(d

B) a

nd O

utpu

t pow

er (

dBm

)

Output power, gain, and drain efficiency at 3.4, 3.5, 3.6, 3.7, and 3.8 GHz

25

Tones at 3.500 GHz and 3.501 GHz each 23 dBm.

34.2 dBm

-10.5 dBm-6.89 dBm

11.5 dBm10.8 dBm

-21.0 dBm

34.2 dBmf1

f5f7

f2

f3 f4

f6

40

30

20

10

0

-10

-20

-30

-40

-503.496 3.497 3.498 3.499 3.5 3.501 3.502 3.503 3.504 3.505

Pow

er (

dBm

)

Frequency (GHz)3.495

Two‐tone input f1 and f2

26

Input tones are at 3.500 GHz and 3.501 GHzFundamental plotted is at 3.501 GHz.

-60

-40

-20

0

20

40O

utpu

t pow

er (

dBm

)

0 5 1510 20 25Input power (dBm)

IM3

Fundamental

3:1

1:1

Response to a two‐tone input signal

U

27

Summary● Transistor vendors strive to offer transistors for

high volume applications that simplify design effort.

● A few standard topologies are used.● For high power amplifier design harmonic

balance analysis is used.– High dynamic range is not available with transient

simulators.

● Load pull analysis used in simulation and also when adjusting final amplifier design.

28

MICROWAVE AND RF Case Study: Amp5 Design of a WiMAX … · CA CB CC BONDWIRES BONDWIRES SOURCE ......

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