Comment on “VCO jitter reduction with bandpass filtering”

Following publication of the Letter `VCO jitter reduction with bandpass filtering´, the author received a critique from G.H.S. Rokos, who pointed out several limitations of the approach and observed that the jitter reduction provided by the post-VCO filter would be minimal for multivibrator phase noise produced by a correlated power spectrum. Furthermore, he pointed out that a single transition phase error such as that analysed in the Letter would cause a permanent phase shift in the multivibrator output, which would eventually be corrected by the phase-locked loop. The post-VCO filter would `at best delay the effect of such an event´. Rokos concluded that the conditions under which the author´s analysis is appropriate are hard to envisage, and they should be stated explicitly. The author acknowledges the points raised and goes on to clarify the conditions under which his analysis is valid