Can anyone please explain me the working of the circuit attached? I believe the op-amp U1 is connected to provide a stable DC voltage at the non inverting terminal of U3. Is my approach correct?
The circuit is able to source a stable DC current of 50uA. However the first challenge is to reduce the output current to levels of about 6nA and 6uA.I was able to get around 6uA while tuning some components randomly. However I am not aware about the effects.
What tuning should I target in order to get the same?
Second challenge is to obtain a AC current out of the circuit. The frequency can be around 30 Hz.
Can I use an op-amp based oscillator instead of VG1 to get the variable frequency current source?
If yes, can someone please guide me for the same?
The input voltage VG1 is 2V DC in this case to obtain 50uA. I know the current required is very less considering the noise that will be induced in the system. However is it even possible using op-amps or do I need to start looking for some other solution?