HCC4046B Datasheet, PDF (3/13 Pages) STMicroelectronics – MICRMICROPOWER PHASE-LOCKED LOOP _

HCC/HCF4046B
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
Figure a : Phase-Comparator I Characteristics at
Low-Pass Filter Output.
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 b : Typical Waveforms for COS/MOS Phase
Locked-Loop Employing Phase Com-
parator I in Locked Condition of fo.
Figure C : Typical Waveforms For COS/MOS Phase-locked Loop Employing Phase Comparator II In
Locked Condition.
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