Phase and frequency detectors for clock synchronization in high-speed optical transmission systems

Several phase and frequency detectors (PFDs) for clock recovery in high-speed optical transmission systems are presented. Their performance is evaluated by means of computer simulations and laboratory experiments using a 140-Mb/s system prototype. The results demonstrate that the proposed detectors substantially increase the loop´s acquisition range with respect to conventional phase detectors without degrading its steady-state jitter performance. The improved acquisition performance is obtained at the expense of a very small increase of the loop hardware complexity. The presented detectors thus turn out to be very attractive for high-speed optical systems as they allow the use of low-cost, low-precision oscillators in the timing recovery loop