I need to make a circuit that squares thee input voltage for the output using a JFET, OP amps, and capacitors and resistors. Basically if the input is 2V i need and output of 4V. Can anyone give any tips or ideas or hints on how to approach this? I also need to extend the range of the JFET if possible and make circuit that does the opposite by taking the square root of the input.

 

Sounds pretty specific. Did you have a configuration in mind? JFET input for high impedance or something?

 

FETs are (generally) linear devices, you will need to incorporate a FET as part of the gain feedback loop of another (FET or Op Amp) to get the exponential output.

 

I need it to be high input impedance. I am pretty lost on how to do this and I looked at my notes and it didn't really help. I was wondering if anyone could give me a thorough explanation.

 

Do you know how to make a multiplier with op-amps? That will square a voltage. You can buy JFET-input op amps to use as a buffer (voltage follower).