What is your amplitude and frequency range at the phase detector?

<nbucska@pcperipherals.com>

Suggestion: Visit
http://www.ednmag.com/ednmag/reg/1996/101096/21di_01.htm
http://www.ednmag.com/ednmag/reg/1999/091699/designideas.htm
etc. for more info

hi
it's very easy to make an analoge multiplier
you can use two logarithmic amplifier then an adder then an anti logarithmic amplifier to make a multiplier.
with just four OP-AMPs and two diods or two transistors and it's very low cost.
with this theory:
x*y=exp(ln(x)+ln(y))
because ln(x)+ln(y)=ln(x*y) and then exp(ln(x*y))=x*y
;)
and making logarithmic and antilogarithmic amplifiers and an adder is very easy.
if you don't know what is a logarithmic amplifier
and you can not make this simple circuit
please email me to this address
kasra_ravanbakhsh@hotmail.com

i'll be glad to help you.
;)

Check the Analog Devices site. I recall they recently introduced a specific phase detector chip. It may not operate low enough in frequency for you though.

Small encore: Visit
http://www.intersil.com/data/FN/FN2/FN2861/FN2861.pdf
etc. for more info