multiplication using analogLib components

Hi

This used to be done with analog multipliers eg AD633. It is a basic IC that simply calculates the multiplication of 2 voltages The problem is that those IC's have become very hard to get as in modern solutions this kind of problem is solved digital

Several years ago I got the same problem in a design and was very lucky to get a free sample. I think it might be possible to build the circuit with operational amplifiers with a special construction of multiple feedback to get the same result

I hope this might help

Gert

I can't help you with simulation, but I can tell you that there is no way to build a multiplier with ordinary op-amps alone as the active elements. Analog multipliers are typically special nonlinear circuits that look sorta like two differential pairs stacked together. They usually need a lot of supporting Rs to set biases and offsets. The RC4200 is one example.

You can use an Operational Transconductance Amplifier like the CA3080 to make a simple

You can also use log amps, even homebrew versions using diode nolinearities if you don't need great accuracy.

For low frequencies, a common multiplier method is to use one input to control a pulse width modulator which chops the other input, then average the result.

Probably a few methods I missed, but the take-home message is that analog multiplication is non-trivial in the real world.

Best regards,

Bob Masta DAQARTA v4.51 Data AcQuisition And Real-Time Analysis

Reply Can't comment on Analog Artist; but in LTSpice I use the "arbitrary behavioral voltage source" e.g.

SYMATTR InstName B1 SYMATTR Value V=V(carrier)*V(env)