2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA...

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2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović Department of Electrical and Computer Engineering University of Colorado, Boulder William McCalpin dBm Engineering, Boulder, CO, USA Funded by: dBm Eng. WPAFB DARPA IRFFE
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Transcript of 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA...

Page 1: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Load-Pull Based Design of Ultra-Linear

W-CDMA Base-Station Power AmplifiersSrdjan Pajić and Zoya Popović

Department of Electrical and Computer EngineeringUniversity of Colorado, Boulder

William McCalpindBm Engineering, Boulder, CO, USA

Funded by:

dBm Eng.WPAFBDARPA IRFFE

Page 2: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Overview

• Motivation for load-pull based PA design

• Description of method for linearity design (~2GHz, 60W LDMOS, -45dBc ACPR)

• Resulting PA characterization

• Discussion: other PAs designed using load-pull (high-efficiency with dynamic biasing etc.)

Page 3: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Usual Approach to PA Design

PA Specs

Device Selection

Nonlinear modelavailable?

YES NO

Performance/ tradeoffanalysis using nonlinear sim.

Small-signal analysisLoad-line analysis

Load-pull

Target impedancesZL, ZS

Matching / biasing networksynthesis

Layout, fabrication, assembly

Performance measurement

Meet the specs?

YES

NOTuning

END

80-90% of time

10-20% of time

Page 4: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Load-pull Based PA Design, Systemathic ApproachGiven Uncharacterized

Power Transistor(Internally prematched)

Static DC Characterization

Target impedances selectionZL, ZS

Initial matching / biasingnetwork design

Break apart PA fixture design

Performance measurement

Meet the specs?

YES

YES

Fine tuning

END

POUT, ZL and ZS estimation(load-line theory)

Test-fixture prematchingnetwork design

Lo

ad-p

ull

char

acte

riza

tio

n

Automated load-source pullcharacterization using

prematching tuners

Parameter sensitive?(low impedance levels, high-Q transistor

impedances, wide bandwidth

NO

EM Modeling of microstripdiscontinuities

Lumped component modeling or measurement

Matching network redesign

Tuning analysis

YES

NO

Pretuning10% of the design time

Page 5: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Design Example: WCDMA Base-Station PA

Commercial load-pull system (Focus Microwaves)

Experimental (uncharacterized) device:

• LDMOS, 42-finger, internally matched to ~3• VDDMAX= 66V, IDDMAX= 11 A (DC pulsed testing) • Frequency range: 2.11GHz – 2.17GHz• Expected CW output power: 70W• Expected power gain: 12 dB• Recommended drain voltage: 28V

Page 6: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

ACPR = - 45 dBc

3GPP Test Model 1, 16 DPCH, 10dB peak/av., 0.01% CCDF

ZS = (8.5 + j0) f = 2.11 GHz ZL = (1.5 – j3.25)

Source-Pull Load-Pull

Design Example: WCDMA Base-Station PA

Page 7: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Design Example: WCDMA Base-Station PAACPR = - 45 dBc

3GPP Test Model 1, 16 DPCH, 10dB peak/av., 0.01% CCDF

ZS = (7 + j0) f = 2.17 GHz ZL = (1.5 – j3.0)

Source-Pull Load-Pull

Page 8: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Final PA

Input Bias

Input Matching

Output Bias

Output MatchingPA matching and biasing network

microstrip substrate: h = 0.787 mm, R = 2.5

Design Example: WCDMA Base-Station PA

Page 9: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Parameter variations:

• microstrip line dimension width: ±100 m

• capacitor tolerance: 5% ZL variation:

Re {ZL}: (1.3 1.6) Im {ZL}: -(2.6 3.3)

Expected performance variation:

Output power @ ACPR < -45 dBc: 0.5 dB

Power gain @ ACPR < -45 dBc: 0.75 dB

Yield analysis of the output matching network

Constant Power Gain (dashed)

Constant Output Power (solid)

Design Example: WCDMA Base-Station PA

Page 10: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Tuning response

C1,2 C3

Output PA circuit half

C1 C2

C3

C4

Comparison for output matching network

Initially measured

ZL

ADS ZL Target ZL

Momentum ZL

Design Example: WCDMA Base-Station PA

Page 11: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Source impedance Load impedance

2.11GHz

2.17GHz

2.11GHz

2.17GHz

Measured ZS 2.11GHz Measured ZL

Target ZS Target ZL

Pre-tuning / verification circuit and tuning results

C1

C2

C3

C4

12.7 mm

Design Example: WCDMA Base-Station PA

Page 12: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

f = 2.11 GHz f = 2.17 GHz

Measured power-sweep parameters of the PA designed using this method

Load-pull, ACPR = -45 dBc Final PA , ACPR = -45 dBc

f [GHz] Pout [dBm] Gain [dB] Pout [dBm] Gain [dB]

2.11 38.5 12.3 38.6 11.8

2.17 39 12.2 38.9 11.8

Design Example: WCDMA Base-Station PA

Page 13: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

DiscussionSystematic design procedure leads to one-pass PA design:

• DC characterized device output power estimates

• load-line theory approximate range of load impedances

• multiple prematching load-pull characterization accurate and reliable target impedances ZS and ZL

• matching network synthesis using EM modeling of microstrip lines and lumped element modeling (or measurement) initial load/source impedances close to targets

• pretuning of amplifier halves using calibrated break-apart test fixture avoids extensive postproduction tuning.

Example design – 60W WCDMA base station PA (and many others…)

Approach can be applied for wide frequency and power range and practically any kind of linearity/efficiency requirements. For example…

Page 14: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

A High-Efficiency High-Frequency Example

First principles assisted by load-pull measurements for first-pass success- 10-GHz class-E hybrid PA

Page 15: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

Two-stage class-E PA designed for increased gain, using “bias-pull” and same impedances for the 2 stages

Page 16: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

AM-PM characterization:Switched-mode PAs enable amplitude modulation through bias

PA alone with varying Vds

PA with constant Vds

PA with closed-loop dynamic bias control

Maintaining high efficiency while output power varies

Adaptive amplifier

Page 17: 2004 IEEE Topical Workshop on Power Amplifiers Load-Pull Based Design of Ultra-Linear W-CDMA Base-Station Power Amplifiers Srdjan Pajić and Zoya Popović.

2004 IEEE Topical Workshop on Power Amplifiers

High-efficiency signal-adaptive X-band PA, slow and fast dynamic biasing