General Description
The SY88403BL is a low-power limiting post amplifier
optimized for copper applications. 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
SY88403BL quantizes these signals and outputs
typically 800 mVPP voltage-limited waveforms.
The SY88403BL operates from a single +3.3V ±10%
power supply, over an industrial temperature range of
−40°C to +85°C. With its wide bandwidth and high gain,
signals with data rates up to 4.25 Gbps and as small as
5 mVPP can be amplified to drive devices with CML
inputs or AC-coupled PECL inputs.
The SY88403BL incorporates a loss-of-signal (LOS)
open-collector TTL output with internal 4.75 kΩ pull-up
resistor. A programmable loss-of-signal level set pin
(LOSLVL) sets the sensitivity of the input amplitude
detection.
LOS asserts high if the input amplitude falls below the
threshold set by LOSLVL and de-asserts low
otherwise. LOS can be fed back to the enable bar (/EN)
input to maintain output stability under a loss of signal
condition. /EN de-asserts the true output signal without
removing the input signal. Typically, 3.5 dB LOS
hysteresis is provided to prevent chattering.

Features
• Multi-Rate up to 4.25 Gbps Operation
• 5 mVPP Input Sensitivity
• Low Noise 50Ω CML Data Outputs
- 800 mVPP Output Swing
- 60 ps Edge Rates
- 1psRMS Typ. Random Jitter
- 10psPP Typ. Deterministic Jitter
• Chatter-Free Loss-of-Signal (LOS) Output
- 3.5 dB Electrical Hysteresis
- OC-TTL Output with Internal 4.75 kΩ Pull-Up
Resistor
• Programmable LOS Sensitivity Using Single
External Resistor
• Internal 50Ω Data Input Termination
• TTL /EN Input Allows Feedback from LOS
• Wide Operating Range:
- Single 3.3V ±10% Power Supply
- Industrial Temperature Range: −40°C to
+85°C
• Available in a 16-pin QFN Package

Applications
• 1.062 Gbps, 2.125 Gbps, and 4.25 Gbps Fibre
Channel
• Cable Driver
• Small Form Factor (SFF) and Small Form Factor
Pluggable (SFP) Transceivers
• High-Gain Line Driver and Line Receiver