PRELIMINARY

This document contains information on a product under development at Advanced Micro Devices. The information

is intended to help you evaluate this product. AMD reserves the right to change or discontinue work on this proposed

product without notice.

Publication# 21560

Rev: A Amendment/+1

Issue Date: April 1998

Am79761

Physical Layer 10-Bit Transceiver for Gigabit Ethernet

(GigaPHY™-SD)

DISTINCTIVE CHARACTERISTICS

n Gigabit Ethernet Transceiver operates at

1.25 Gigabits per second (Gbps)

n Suitable for both Coaxial and Optical Link

applications

n 10-bit TTL Interface for Transmit and Receive

Data

n Monolithic Clock Synthesis and Clock Recovery

requires no external components

n Word Synchronization Function (Comma

Detect)

n Low Power Operation - 700 mW typical

n 64-pin Standard PQFP

— 14 x 14 mm (0˚ C - 70˚ C)

— 10 x 10 mm (0˚ C - 50˚ C)

n 125 MHz TTL Reference Clock

n Loopback Diagnostic

n Single +3.3 V Supply

GENERAL DESCRIPTION

The Am79761 Gigabit Ethernet Physical Layer Serial-

izer/Deserializer (GigaPHY-SD) device is a 1.25 Gbps

Ethernet Transceiver optimized for Gigabit Ethernet/

1000BASE-X applications. It implements the Physical

Medium Attachment (PMA) layer for a single port.

The GigaPHY-SD device can interface to fiber-optic

media to support 1000BASE-LX and 1000BASE-SX

applications and can interface to copper coax to sup-

port 1000BASE-CX applications.

The functions performed by the device include serializ-

ing the 8B/10B 10-bit data for transmission, deserializ-

ing received code groups, recovering the clock from the

incoming data stream, and word synchronization.

When transmitting, the GigaPHY-SD device receives

10-bit 8B/10B code groups at 125 million code groups

per second. It then serializes the parallel data stream,

adding a reference clock, and transmits it through the

PECL drivers.

When receiving, the GigaPHY-SD device receives the

PECL data stream from the network. It then recovers

the clock from the data stream, deserializes the data

stream into a 10-bit code group, and transmits it to the

Physical Coding Sublayer (PCS) logic above. Option-

ally, it detects comma characters used to align the in-

coming word.