phase comparator

From: Jamie Morken (jmorken_at_shaw.ca)
Date: 01/04/05 

Date: Tue, 04 Jan 2005 16:47:58 GMT

Hi,

I would like to compare the phase of two 1MHz sinewave and/or
squarewave) signals and get a output voltage proportional to their phase
shift, with a small phase angle error ie. 1% if possible. Also what
happens when the amplitudes of the two input signals are different, and
what happens if the frequency isn't exactly the same? (ie. from a
doppler shift)

Is there a common circuit for comparing the frequencies of two signals
as well (and outputting a voltage proportional to the frequency difference)?

Is an XOR gate with a lowpass filter on its output essentially a phase
comparator?

I am slowly learning more about modulators/demodulators and upconverters
and downconverters, and am a bit confused on how these devices can be
used for FM and PSK etc..

Is there a reason why an IQ modulator/demodulator can be made to operate
over a large frequency range without needing external tuning caps/coils
(ie. AD8346/AD8347) while a downconverter/upconverter (ie.
max2680/max2660) requires external tuning passives depending on the
frequencies of operation? Is this because an IQ modulator/demodulator
is "balanced" from the I and Q being 90degrees out of phase?

cheers,
Jamie Morken

Relevant Pages

  • Re: phase comparator
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