Simulation Studies on Nonlinear Bit Synchronizers in APD-Based Optical Receivers

This paper examines the problem of self bit synchronization employing nonlinear timing extraction schemes in optical receivers with avalanche photodetectors (APD) through digital computer simulation. A direct algorithm is developed for the simulation of sample functions of the APD output process with due consideration to intersymbol interference (ISI). Simulation of all the functional blocks used for synchronization is carried out in the discrete time domain. Performances of the nonlinear timing recovery schemes are evaluated in terms of the rms timing jitter for nonreturn-to-zero (NRZ) as well as return-to-zero (RZ) signaling formats.