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.