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Hello everyone!

I'm trying to simulate a circuit (that I designed, for better or worse) that squares the input voltage. I run the input voltage through a log amplifier, then through an amplifier which multiplies it by two, and then through an antilog amplifier which should result in the square of the input voltage.

If I set R3 to 1K, then the multiplication is by one, which results in the output equaling the input voltage, which is correct. However, if I set R3 to 2K, then I get some very crazy voltage outputs. Also, if I set R3 to 500 ohms, this should result in the square root of the input, but doesn't appear to.

What am I doing wrong?

Could it be the voltage range that it works over?

Thanks!

I think I figured it out. It only appears to work over a very narrow range of input voltages.