Performance improvement of all digital phase-locked loop with adaptive multilevel-quantized phase comparator

A type of phase comparator for digital phase-locked loops, called the adaptive multilevel quantized phase comparator (AMPC), is proposed. The phase comparison characteristics of this proposed comparator operate adaptively, by shifting them up or down and by changing the scale, following the frequency deviation and the phase jitter of the input signals. The performances of the AMPC and the loop with AMPC are obtained theoretically and verified by computer simulation. As a result, the loop with this AMPC has a much wider locking-range and a much better jitter suppression effect than those of the conventional loop, as well as an improved steady-state phase error.<>