Single-Photon Avalanche Photodiode Based Fiber Optic Receiver for Up to 200 Mb/s

The first fully integrated receiver based on singlephoton avalanche diodes (SPADs) for data rates of up to 200 Mb/s is reported. An array of four SPADs in combination with quenching circuits and a short dead time of 3.5 ns is fabricated in a 0.35 mu m CMOS process. The responses of the SPADs are combined using an integrated digital latch-type processing circuit to create a single output data stream. In addition, the output of each quenching circuit is recorded and the bit error rates are extracted by post-processing in MATLAB. Using a 635-nm single-mode laser source, the bit error rate at different optical power is measured at 50, 100, 150, and 200 Mb/s. The integrated digital circuit achieved the best sensitivity at -46.3 dBm (BER = 2 . 10(-3)) for 100 Mb/s. Using the MATLAB postprocessing, a sensitivity of -43.8 dBm at 200 Mb/s (BER = 6.5 . 10(-3)) is reached.