AN-0974

APPLICATION NOTE

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Multicarrier TD-SCMA Feasibility

by Brad Brannon, Bill Schofield, and Yang Ming

Rev. 0 | Page 1 of 28

ABSTRACT

The goal of this application note is to demonstrate the feasibility

of implementing a multicarrier TD-SCDMA transceiver and

describe what the major subsystem performances must be.

POWER

AMPLIFIER

POWER DETECT

AND GAIN CO NT RO L

ANTENNA

BPF

BAND

SELECT FILTER

90°

0°

TUNING

CONTROL

BPF ADC DSP

CLO CK DIST RIBUTIO N

LPF DAC

DUC

AND PAPR

DSP

DSP CL US TER

NETWORK

INTERFACE

AD6633

AD9516

AD9230

ADL5355

ADF4350

ADF4106

AD8362

ADL5372

AD9779

AD9788

PA PREDISTORTION OBSERVATIO N PATH

07663-001

Figure 1. Direct Upconversion Architecture

AN-0974 Application Note

Rev. 0 | Page 2 of 28

TABLE OF CONTENTS

Abstract .............................................................................................. 1

Transmit Discussion ......................................................................... 3

General Architecture .................................................................... 3

Carrier Configurations ................................................................ 3

Frequency Error ............................................................................ 3

Physical Layer Structure .............................................................. 4

Power Control ............................................................................... 5

Code Domain Formation ............................................................ 6

Transmit Modulation ................................................................... 6

Transmit Diversity ........................................................................ 7

Peak-to-Average Ratio (Crest Factor) ........................................ 9

Peak-to-Average Power Reduction ............................................ 9

Power Amplifier Linearization ................................................. 11

ACLR ............................................................................................ 14

Signal Chain Analysis ................................................................ 15

Receive Discussion ......................................................................... 21

General Architecture ................................................................. 21

Receiver Requirements .............................................................. 24

Receiver Operating Conditions ................................................ 24

Assumptions ................................................................................ 24

ADC SFDR Requirements ........................................................ 25

Comments on Gain, Fixed or Variable .................................... 26

Validation .................................................................................... 26

Margin for a Six-Carrier Receiver ............................................ 27