REV. B

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a

AD7002

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1997

GSM Baseband I/O Port

FUNCTIONAL BLOCK DIAGRAM

10-BIT DAC

10-BIT DAC

2.5V

REFERENCE

REFERENCE

OUTPUT BUFFER

AD7002

I Tx

Q Tx

REF OUT

I Rx

Q Rx

AUX

FLAG

CLK2

AV

AGND

Tx SLEEP

Tx DATA

THREE-STATE

ENABLE

Rx DATA (I DATA)

AUX DATA

AUX CLK

AUX LATCH

Rx SLEEP1

Rx SLEEP2

GMSK PULSE

SHAPING ROM

DD

DGND

DV

DD

4TH ORDER BESSEL

LOW-PASS FILTER

4TH ORDER BESSEL

LOW-PASS FILTER

AUX

DAC 1

AUX

DAC 2

AUX

DAC 3

9-BIT DAC

10-BIT DAC

8-BIT DAC

16-BIT SHIFT REGISTER

CLK1

MZERO

Σ−∆ MODULATOR

Σ−∆ MODULATOR

Tx CLK

Rx SYNC

I CHANNEL

DIGITAL FIR FILTER

OFFSET REGISTER

Q CHANNEL

DIGITAL FIR FILTER

OFFSET REGISTER

RECEIVE

CHANNEL

SERIAL

INTERFACE

Rx CLK

RATE

MODE

CAL

SWITCH-CAP

FILTER

SWITCH-CAP

FILTER

I/Q (Q DATA)

FEATURES

Single +5 V Supply

Transmit Channel

On-Chip GMSK Modulator

Two 10-Bit D/A Converters

Analog Reconstruction Filters

Power-Down Mode

Receive Channel

Two Sigma-Delta A/D Converters

FIR Digital Filters

On-Chip Offset Calibration

Power-Down Mode

3 Auxiliary D/A Converters

Power-Down Modes

On-Chip Voltage Reference

Low Power

44-Lead PQFP

APPLICATIONS

GSM

PCN

GENERAL DESCRIPTION

The AD7002 is a complete low power, two-channel, input/

output port with signal conditioning. The device is used as a

baseband digitization subsystem, performing signal conversion

between the DSP and the IF/RF sections in the Pan-European

telephone system (GSM).

The transmit path consists of an onboard digital modulator,

containing all the code necessary for performing Gaussian Mini-

mum Shift Keying (GMSK), two high accuracy, fast DACs with

output reconstruction filters. The receive path is composed of

two high performance sigma-delta ADCs with digital filtering. A

common bandgap reference feeds the ADCs and signal DACs.

Three control DACs (AUX DAC1 to AUX DAC3) are in-

cluded for such functions as AFC, AGC and carrier signal shap-

ing. In addition, AUX FLAG may be used for routing digital

control information through the device to the IF/RF sections.

As it is a necessity for all GSM mobile systems to use the lowest

power possible, the device has power-down or sleep options for

all sections (transmit, receive and auxiliary).

The AD7002 is housed in 44-lead PQFP (Plastic Quad Flatpack).