Comment on "Optimal Design of PLL with Two Seperate Phase Detectors"

This correspondence comments on a recent paper by Heiman and Bar-Ness. In the paper the authors propose a two-channel PLL and pursue an optimization analysis of the proposed configuration. They base the analysis on Viterbi´s equivalent noise model. In our comment it is shown that their application of the model suffers from a fundamental flaw. Difficulties in the physical interpretation of the results are demonstrated.