A linear equalizer for high-speed APD-Based integrate-and-dump receivers

A linear minimum mean-square error (LMMSE) equalizer for avalanche-photodiode (APD) based integrate-anddump receivers is designed to compensate for intersymbolinterference (ISI) introduced by the APD’s random impulse response. Recent work on the characterization of the joint probability distribution of the APD’s gain and buildup-time are adopted and utilized to determine the mean and correlation matrix of the APD-based receiver’s random impulse response. This LMMSE equalizer is shown to improve the bit-errorrate dramatically at high transmission rates, resulting in an improvement in the receiver sensitivity by approximately 2.3 dB at 15GHz.