input over the full VCO frequency range. Moreover,

the power dissipation due to the low-pass filter is re-

duced when this type of phase comparator is used

because both the p- and n-type output drivers are

OFF for most of the signal input cycle. It should be

noted that the PLL lock range for this type of phase

comparator is equal to the capture range, inde-

pendent of the low-pass filter. With no signal present

at the signal input, the VCO is adjusted to its lowest

frequency for phase comparator II. Fig. (c) shows

typical waveforms for a COS/MOS PLL employing

phase comparator II in a locked condition.

Figure a : Phase-Comparator I Characteristics at

Low-Pass Filter Output.

Figure b : Typical Waveforms for COS/MOS Phase

Locked-Loop Employing Phase Com-

Figure C : Typical Waveforms For COS/MOS Phase-locked Loop Employing Phase Comparator II In

Locked Condition.

HCC/HCF4046B

3/13