An SAGM avalanche photodiode optical receiver for 2 Gb/s and 4 Gb/s.

A high sensitivity optical receiver has been designed using an InGaAs SAGM avalanche photodetector and a low capacitance GaAs FET preamplifier. The hybrid preamplifier circuit consists of two common source amplifier stages with feedback from drain to gate at the first stage for improved dynamic range. The total input capacitance achieved is 0.63 pF. Receiver sensitivities obtained at 1.51microns are -36.6 dBm at 2 Gb/s and -31.2 dBm at 4 Gb/s. These are the best results reported to date at these bit rates.