The SY88149CL is a high-sensitivity limiting post amplifier designed for use in fiber-optic receivers. These devices connect 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 SY88149CL quantizes these signals and outputs PECL level waveforms.

The SY88149CL operates from a single +3.3V power supply, over temperatures ranging from -40°C to +85°C. With its wide bandwidth and high gain, signals with data rates up to 1.25Gbps, and as small as 5mVPP, can be amplified to drive devices with PECL inputs.

The SY88149CL generates a high-gain signal-detect (SD) open-collector TTL output. The SD function has a high gain input stage for increased sensitivity. A programmable Signal Detect level set pin (SD LVL) sets the sensitivity of the input amplitude detection. SD asserts high if the input amplitude rises above the threshold set by SD LVL and de-asserts low otherwise. The enable input (EN) de-asserts the true output signal without removing the input signal. The SD output can be fed back to the EN input to maintain output stability under a loss-of-signal condition. Typically, 3.4dB SD hysteresis is provided to prevent chattering.