- Phase Frequency Detector
A phase frequency detector, in electronics, is a device which compares the phase of two input signals. It has two inputs which correspond to two different input signals, usually one from a
voltage-controlled oscillator (VCO) and another from some external source. It has two outputs which instruct subsequent circuitry on how to adjust to lock onto the phase. The outputs are fed to a loop filter which integrates the signal to smooth it. This smoothed signal is fed to a voltage-controlled oscillator. The VCO provides an output clock with a frequency that is proportional to the level of the input voltage, which is then fed back to the PFD.References
* cite paper
author=Devon Fernandez and Sanjeev Manandhar
date=8 December 2003
url=http://www.eece.maine.edu/vlsi/DPLL2003/Devon_Sanjeev.pdf
title=Digital Phase Locked Loop
accessdate=2006-04-25
* cite news
first=Zeljko
last=Zilic
url=http://www.techonline.com/community/related_content/14627
title=Phase- and Delay-Locked Loop Clock Control in Digital Systems
work=TechOnLine
date=2001-08-17
accessdate=2006-04-25
* cite news
author=Mike Curtin and Paul O'Brien
url=http://www.analog.com/library/analogDialogue/archives/33-07/phase3/
title=Phase Locked Loops for High-Frequency Receivers and Transmitters-3
work=Analog Dialogue
publisher=Analog Devices
date=July/August 1999
accessdate=2006-04-25
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