3.3V, 1.25Gbps PECL Limiting Post
Amplifier with High-Gain TTL Loss-of-
Signal
SY88147DL 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
M9999-011606-A
or (408) 955-1690
General Description
The SY88147DL 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 SY88147DL quantizes
these signals and outputs PECL-level waveforms.
The SY88147DL operates from a 3.3V power
supply, over an industrial temperature range of –40°C
to +85°C. With its wide bandwidth and high gain,
signal with data rates up to 1.25Gbps, and as small as
5mV
pp
can be amplified to drive devices with PECL
inputs.
The SY88147DL features an open-collector, TTL loss-
of-signal (LOS) indicator. 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, 3.5dB LOS hysteresis is provided
to prevent chattering.
This manual provides information on the SY88147DL
evaluation board. It should be used in conjunction with
the SY88147DL data sheet, which contains the full
specifications of the SY88147DL.
The SY88147DL evaluation board enables fast and
thorough evaluation of the SY88147DL. 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 50
Ω
terminations for the generator’s
outputs. The input termination network also provides
the required input bias of V
CC
–1.3V for the
SY88147DL.
The SY889147DL evaluation board is intended to
terminate to a 50
Ω
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
•
LOS
Indicator
•
Chatter-free open-collector TTL loss-of-signal
(LOS) output with internal 4.75k
Ω
pull-up resistor
•
TTL /EN input
•
Programmable LOS level set (LOS
LVL
)
•
AC-coupled I/O with SMA connectors
•
50
Ω
input network termination
Related Documentation
•
SY88147DL, 3.3V, 1.25Gbps PECL Limiting Post
Amplifier w/ High-Gain TTL LOS Data Sheet
Evaluation Board
