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3.3V, 1.25Gbps PECL High-Sensitivity

Limiting Post Amplifier with TTL

Loss-of-Signal

SY88903AL Evaluation Board

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

January 2006

M9999-010406-B

[email protected] or (408) 955-1690

General Description

The SY88903AL high-sensitivity, limiting post amplifier

is designed for use in fiber-optic receivers. The device

connects to typical transimpedance amplifiers (TIAs).

The linear signal output from TIAs can contain

significant amounts of noise and may vary in

amplitude over time. The SY88903AL quantizes these

signals and outputs PECL-level waveforms.

The SY88903AL operates from a single +3.3V power

supply, over an industrial temperature range of –40°C

to +85°C. With its wide bandwidth and high gain

signals and with data rates up to 1.25Gbps, and as

small as 5mV

pp

, it can be amplified to drive devices

with PECL inputs.

The SY88903AL generates a high-gain, loss-of-signal

(LOS), open-collector, TTL output. The LOS function

has a high gain input stage for increased sensitivity. A

programmable loss-of-signal level set pin (LOS

LVL

)

sets the sensitivity of the input amplitude detection.

LOS asserts high if the input amplitude falls below the

threshold set by LOS

LVL

and de-asserts low otherwise.

The enable bar input (/EN) de-asserts the true output

signal without removing the input signal. The LOS

output can be fed back to the enable bar (/EN) input to

maintain output stability under a loss-of-signal

condition. Typically, 3.4dB LOS hysteresis is provided

to prevent chattering.

This manual provides information on the SY88903AL

evaluation board. It should be used in conjunction with

the SY88903AL data sheet, which contains full

specifications of the SY88903AL.

The SY88903AL evaluation board enables fast and

thorough evaluation of the SY88903AL. The board is

an easy-to-use, single supply design. It’s designed to

be driven by a high-speed, pattern generator and

provides onboard 50Ω terminations for the generator’s

outputs. The input termination network also provides

the required input bias of V

CC

–1.3V for the

SY88903AL.

The SY88903AL evaluation board is intended to

terminate to a 50Ω scope and provides for simple user

adjustability of the LOS threshold through the

adjustment of an on-board potentiometer.

All data sheets and support documentation can be

found on Micrel’s web site at: www.micrel.com.

Features

•Single 3.3V supply

•DC-to-1.25Gbps operation

•Low-noise PECL data outputs

•High-gain LOS

Chatter-free open-collector TTL loss-of-signal

(LOS) output with internal 4.75kΩ pull-up resistor

•TTL /EN input

•Programmable LOS level set (LOS

LVL

)

•Available in a tiny 10-pin MSOP

•AC-coupled I/O with SMA connectors

•50Ω input network termination

Related Documentation

•SY88903AL, 3.3V, 1.25Gbps PECL High-

Sensitivity Limiting Post Amplifier w/ TTL LOS Data

Sheet

Evaluation Board

Product specificaties