Without a description I am not certain what you are after with the circuit. I ran it through PSPICE (Student) {FREE by the way} and got the following results with both pots set at 10K. For 0V input: With a command of 0V output is 2.2V, command of 5V yields 7.7V and a command of 10V yields 13.2V. So the loop gain for the command is 11/10 or 1.1 with an offset of 2.2V. Or, for the form y = mx + b; Vout = 1.1 * Vin + 2.2. Looks very linear to me. Now, for a command of 5V which we know will have a DC output of 7.7V and an input AC signal varying from -20mV to +20mV (40mV p-p) the output varies from 5.7V to 9.7V. Again, this is linear around the command input of 5V with a gain of 4V / 0.04 or 100. Of course the simulation is assuming ideal op amps and dual supplies (+15,-15) and simulations are not the real hardware. Nevertheless, you can apply 0 signal and expect to get the results above. Give a command of 5V with a signal source of 40mV p-p you should come close to the results of the AC analysis. As to how the MOSFETs react to the output - I didn't get into that. Perhaps the non-linearity is in the drivers, not the amplifiers. Then again, simulations are sometimes just plain wrong! --- In , R Ramesh <ramesh_21_in@y...> wrote: > Thankx a lot . > Here I attached my simple circuit to control the current and stablize it . > > For ur information SHUNT is the part that I have mentioned in last mail, where I get the feedback . If u got any more Idea plz forword the circuits , > > best regards, > Ramesh > --------------------------------- > |