I want to build a multipier with some amp

[mag]

My project need a analog multiplier,but special multiplier chip is very expansive,So I want to build a multipier with some amp,but how can I to select amp for it,and which parameter need ?

 

[flatulent]

Do you want two or f our quadrant multiplication? If you want four you are stuck with the IC versions for any degree of linearity. For two you can use a differential pair with a variable current source and resistive loads. One input to be multiplied controls the current, the other input goes to the differential pair. You then convert to single ended and remove the common mode with a differential configuration op amp.

 

[eternal_nan]

To expand on Flatulent's response, you can build a four quadrant multiplier out of Gilbert cells (they can be constructed out of <10 discrete transistors). Refer to the following link:

**broken link removed**

 

[mag]

I have fewer resource about analog multiplier,I need detailed information about it.
and my project application:
I need a const power controling,power=V*I,(V and I all are positive),I want to use a multiplier to generate power with V and I.
what's type multiplier need my project?