hej guys,
I am puzzled with a problem which appeared simple on the first glance, but now after hours and hours of experimenting with simulator I am totally lost...
My challenge is:
- I have a function as voltage fed into op-amp
- I am asked to build a circuit with as few op-amps as possible to get 1/f(x)
T.ex.: y=x (input) -> y=1/x (output)
Any suggestions?

 

google logarithmic and antilogarithmic amplifier.

 

Already did... and even simulated several circuits candidates.... in theory, LOG -> Inverse -> Antilog should do the trick.... first two works just fine, but after the last transformation I get something very poorly looking like 1/x After talking to my tutor I was surprised to know this is possible to do with 1 LOG and one (and only one!) additional op-amp! But he never tells the whole picture!

 

One post is enough:

http://forum.allaboutcircuits.com/threads/how-to-get-1-x-function-with-op-amp.103068/