Sink+Source Refence Current Generator Stability

[celebrevida]

I have designed the following Isource and Isink current reference generator with Isource=Isink on purpose.

When I simulate this circuit in DC, it works. SPICE will find the final steady state solution that I seek.

But in TRAN, the circuit is unstable and the two opamps fight each other forever.

Is there a way to get this circuit to stabilize? I tried many different values of the RC miller feedback for each opamp but it doesn't work.

(I could of course break the circuit up into two indepence Isource and Isink references but the whole purpose is to ensure Isource=Isink)

Thanks for any insight and help!

 

[KlausST]

Hi,

I guess you just need one capacitor or RC at one variable_resistor_end to GND to prevent the circuit form oscillating.

If you expect to give some recommendations for the values, you need to give your design values first.

Klaus