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Page 1: Power Amplifier Linearization using RF Pre-Distortion

JUNE, 2012

Power Amplifier Linearization using RF Pre-Distortion

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Page 2: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

General principles

Overview/Block Diagram of DPD and RFPD

RFPAL System architecture & Implementation

PA Linearization Overview

Page 3: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

Predistortion Principle

3

No predistorion

With predistorion

5-10 x BW expansion

Page 4: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

Digital Pre-Distortion (DPD)

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Without PA/DUC/CFR : Power consumption ~5.4W

Up-ConverterDPDDUC

CFR

Driver & PA

PwrDet

PwrDet

LO

DSP

5xCLK

f

Wanted Signal + Predistortion

= ~ 5 x Wanted Signal

f

Wanted Signal

f

0 LO0

0.3W1.5W

0.1W

0.8W0.6W

0.1W

ADC

DAC

DAC

0.8W

Clock Generator

Down-Converter

0.4W

0.8W

ADC

f

LO

Wanted SignalWanted Signal +

Predistortion= ~ 5 x Wanted Signal

Filter / Duplexor

Page 5: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

RFPAL (RF PA Linearization)

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Without PA/DUC/CFR Power consumption ~1.4W

Driver & PA

Filter / Duplexor

LO1xCLK

ScinteraRFPAL

ff f f

0 LO LO LO

0.1W 0.4W

Clock Generator

Up-Converter

0.1W

0.8W

DUCCFR

DAC

DAC

Optional digital link

to BB

Wanted Signal + Predistortion

= ~5 x Wanted SignalWanted Signal

Wanted Signal

Wanted Signal

Page 6: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

RFPAL System Architecture & Implementation

Page 7: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

RFPAL Application

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Page 8: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

RFPAL System Architecture

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DIGITAL SIGNAL PROCESSOR (DSP)FFT, error metric, etc.

Digital Controller

RF VGAQPS

0o

90o

Voltage & Timing references, LO Generation, etc.

CORRECTION PROCESSOR

Memory

MONITOR

RFIN RFOUTCorrection Signal

RFFBFeedback Signal

Input Monitor Path

Feedback Monitor Path

RF PA Linearizer

ADC

ADC

OptionalDigital Interface

I

Q

DAC

VOLTERRASERIES

IQ

DAC

VGA

VGA

POWER DETECTOR

CoefficientDACs

Volterra SeriesGenerator

PDET AGC

Page 9: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

2.54 cm

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Scintera Advantages

Single chip CMOS linearization solution Easy to evaluate and design in Simplifies TX chain

High system efficiency Very low power consumption

Low system cost Small footprint Future proof

In-system & in-field reprogrammable RFin/RFout supports stand-alone PAs Waveform & modulation independent Power Amp Independent

Linearize even lowest power PAs Robust & field-proven solution

2.54 cm

Page 10: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

More Complete Information on Theory of Operation and Datasheets Available on Line at www.scintera.com or Richardson RFPD website Please Visit Us at Booth # 208

Page 11: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications

Additional Slides

Page 12: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications 12

Analog Volterra Series

∑∑==

=5

1mp

2.mp,2.m

4

1pOUT )-(trc(t)V τ~(t)r(t)V 2

IN =

C1,2

C1,4

C1,6

C1,8

C1,10

X2

X4

X6

X8

X10

Delay 1= τ1 Coefficient DAC’s

Delay 2= τ2

Delay 3= τ3

Delay 4= τ4

Vout(t)

Vin(t)

Page 13: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications 13

RFPAL Key Architectural Attributes Analog (RF & BB), Digital (high & low-speed) and SW partitioning minimize power & area

Computation of correction terms in digital (software and hardware) domain Application of correction in the analog domain

RF and most of baseband analog circuitry is unclocked enables robustness and flexibility for various modulation schemes & carrier frequencies.

Flexible Work Function Synthesizes wide range of PA AM/AM and AM/PM compensation and memory compensation (1ns - 300ns) Enables robust adaptation (orthogonal basis terms of work function)

Robust performance with process, voltage, aging and temperature variations Extensive digital/analog compensation loops for analog cells, with process/temp sensing, calibration routines, etc. Optimized calibration algorithms using a low-power, on-chip spectral estimator. Software-driven analog circuit design that can be conveniently tuned /optimized.

Software-driven correction enables flexibility With respect to waveforms, PA, power consumption (duty-cycle), etc. Allows customization of solutions by application and customer

Page 14: Power Amplifier Linearization using RF Pre-Distortion

Semiconductors for Wireless Communications 14

RFPAL Reference PCB

25 mm

Output coupler

RFPAL Linearizer SoC • 9 x 9 x 0.9 mm standard QFN package

Input coupler

Ceramic resonator

RFIN

RFOUT

RFFB

Other: Decoupling + matching networks


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