®

PDS-1460A

Printed in U.S.A. October, 1998

2Mbps, Single Pair HDSL ANALOG FRONT END

FEATURES

q E1/T1 SINGLE PAIR 2B1Q OPERATION

q COMPLETE ANALOG INTERFACE

q 385mW POWER DISSIPATION

q PROGRAMMABLE POWER

AFE1203

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111

Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132

DESCRIPTION

Burr-Brown’s Analog Front End greatly reduces the size and

cost of a single pair HDSL (High bit rate Digital Subscriber

Line) system by providing all of the active analog circuitry

needed to connect an HDSL digital signal processor to an

external compromise hybrid and an HDSL line transformer.

The transmit and receive filter responses automatically change

with clock frequency, allowing the AFE1203 to operate over a

wide range of data rates. The power dissipation of the device

can be reduced under digital control for operation at lower

speeds. The AFE1203 will operate at bit rates from 160kbps to

2.3Mbps. It meets ETSI PSD specifications for single pair E1,

as well as ETSI and ANSI PSD specifications for two pair E1

and T1.

Functionally, this unit consists of a transmit and a receive

section. The transmit section generates, filters, and buffers

outgoing 2B1Q data. The receive section filters and digitizes

the symbol data received on the telephone line. This IC operates

q 48-LEAD SSOP PACKAGE

q SCALEABLE DATA RATE

q OPERATION FROM 2.3Mbps TO 160kbps

q +5V ONLY (5V OR 3.3V DIGITAL)

q –40

on a single 5V supply. The digital circuitry in the unit can be

connected to a supply from 3.3V to 5V. The chip uses only

385mW for full-speed operation. It is housed in a small 48-lead

SSOP package.

The receive channel is designed around a fourth-order delta-

sigma analog-to-digital converter. It includes a difference am-

plifier designed to be used with an external compromise hybrid

for first-order analog echo cancellation. A programmable gain

amplifier with gains 0dB to +9dB is also included. The delta-

sigma modulator, operating at a 24X oversampling ratio, pro-

duces a 14-bit output at symbol rates up to 1168kHz (for

2.3Mbps operation).

The transmit channel consists of a digital-to-analog converter and

switched-capacitor pulse forming network followed by a differ-

ential line driver. The pulse forming network receives symbol

data and generates a standard 2B1Q output waveform. The

differential line driver uses a composite output stage combining

class B operation (for high efficiency driving large signals) with

class AB operation (to minimize crossover distortion).

Pulse

Former

txDAT

txCLK

rxSYNC

rxLOOP

rxGAIN

rxD13 - rxD0

Line

Driver

Voltage

Reference

Delta-Sigma

Modulator

Transmit

Control

Receive

Control

Decimation

Filter

14

2

Patents Pending

D/A

Converter

AFE1203