Dear All

Can anybody can design one circuit which meet my requirement
Input specification
Input current = 12uV to 0.2A
frequency (sinusoidal signal) = 50Hz (fundamental)+ harmonics
Output requirement
Output voltage = ±10mV to ±5V (without any phase shift)
Output harmonics = should not allow more than 11th harmonics.

 

What kind of devices are you allowed, transistors (and how many), op amps, what?

 

Transistors are not recommended. We can use Op-amp, Programmable amplifier and CMOS switches.

 

You can manually adjust the gain to what you want, so you can match the output requirements to the specified output?

Input current = 12uV to 0.2A

I suspect this was a misprint. You would have to have low impedance indeed to have 200ma at 12µv. Am I mistaken?

My thought is a simple noninverting amp with variable gain. You could probably use a 741, the frequency response on this op amp is pretty low, it might even help reject the 11th harmonic by itself (which is 550 Hz, BTW). It sounds like you need an active filter, probably low pass. An RC filter might work, if we could keep the phase shift under control (probably not a problem, have to crunch the numbers though).

About the 741, the power supply requirements are a pain, I'd go with something a little newer. It would work with a ±9V power supply (I'm thinking transistor batteries), but so would everthing else. Most op amps have problems with getting near the power supply rails, so I would not use ±6V.

My current thought looks something like this...