Analogue Mulitiplier

[DPJ]

Hi
can anyone help
I'm using an AD633JN analoge multiplier which is to expensive.
Can anyone suggest alternatives (Im using it as a sine wave phase detector)
many thanks
DPJ

 

[nbucska]

What is your amplitude and frequency range at the phase detector? <nbucska@pcperipherals.com>

 

[jbartos]

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

 

[biomedicalEng]

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)
because ln(x)+ln=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.

 

[johnday]

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.

 

[jbartos]

Small encore: Visit

http://www.intersil.com/data/FN/FN2/FN2861/FN2861.pdf

etc. for more info