Hello, everyone. New participant here.
I recently read an idea about composite opamp circuit and nested feedback, and figured out the about circuit.
(the drawing missing a resistor connecting front opamp positive to ground, 200Kohm)
But when I put it into test, the output is very unstable and distorted.
Even with grounded input there will be DC output.
The only combination worked is using OPA2111 for both opamp.
I wonder if this one theoretically works and if there is room of improvement.
(The idea of this circuit is to gain the benefit of using BUF634 while using an low distortion opamp to push the distortion of BUF634 lower by unity gain.
and the front opamp is used as amplifier at gain=4. My idea is, if use only one opamp with BUF634 to amplify, distortion of BUF634 will just partial feedback to the opamp for correction so the total distortion will be higher.)