The SY88149NDL is a high-sensitivity, burst-mode capable limiting post amplifier designed for Optical Line Terminal (OLT) receiver applications. The SY88149NDL satisfies the strict timing restrictions of the GPON standards by providing ultra-fast Loss-of-Signal (LOS) or Signal-Detect (SD) output. Auto Reset and Manual Reset options are provided to control LOS/SD output timing. For increased flexibility, this device also includes an option to select between LOS or SD output. The device can be connected to burst-mode capable transimpedance amplifiers (TIAs) using AC or DC coupling.

The SY88149NDL generates a high-gain LOS or SD LVTTL output. A programmable LOS/SD level set pin (LOS/SDLVL) sets the sensitivity of the input amplitude detection. When LOS/SD SEL pin is left open or tied to Vcc, JAM is active high, SD is selected and asserts high if the input amplitude rises above the threshold sets by LOS/SDLVL and de-asserts low otherwise. When LOS/SD SEL pin is set low or tied to GND, JAM is active low, LOS is selected and asserts low if the input mplitude rises above the threshold sets by LOS/SDLVL and de-asserts high otherwise. The LOS/SD output can be fed back to the JAM input to maintain output stability under an invalid signal conditions. Typically, 4–5 dB SD hysteresis is provided to prevent chattering.

The SY88149NDL also features a selectable proprietary Noise Discriminator that aids by filtering out input signals that do not qualify as a 1.25Gbps GPON preamble signal in the initial startup phase. This feature minimizes false SD Asserts that can be triggered by random noise.Read more