Hello all,
I feel quite daft for having to ask this:
I am working with Cadence's analog artist environment + Virtuoso schematic editor. I want to multiply 2 voltages (for testbench purposes). I can not seem to find a way to do this using the vccs, cccs dependant sources. Is there a way a simple way to do this ?
(I want to use the product of the voltages to control a vccs in order to emulate a current path)
Any help will be appreciated.
-Roger
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
2-quadrant multiplier.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
Replying to Bob's post because I don't see gmail posts:
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)
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