This LumaOptics Class B+ GPON SFP ONU transceiver is a high performance module for single fiber communications using a 1310nm burst-mode transmitter and a 1490nm continuous-mode receiver. It is used in the optical network terminal (ONT) for GPON ONT Class C+ applications. The Transmitter is designed for single mode fiber and operates at a nominal wavelength of 1310nm. The transmitter module uses a DFB laser diode with full IEC825 and CDRH class 1 eye safety. It contains APC functions, a temperature compensation circuit to ensure compliance with G.984.2 requirement at operating temperature, LVPECL data inputs and DC coupling circuit. The receiver section uses a hermetic packaged APD TIA (APD with trans-impedance amplifier) and a limiting amplifier. The APD converts optical power into electrical current and the current is transformed to voltage by the trans-impedance amplifier. The differential DATA and /DATA CML data signals are produced by the limiting amplifier. The APD TIA is AC coupled to the limiting amplifier through a low pass filter. As the optical input power decreases, the Signal Detect will switch from high to low (de-assert point). As the optical input power is increases, Signal Detect will switch back from low to high (assert point). The assert level is at least 0.5 dB higher than the de-assert level (Signal Detect Hysteresis).