Question is based on this document.
Quoting from there:
Voltage Follower Biasing: This method is exactly the same as the voltage divider biasing, except it uses an op-amp (or transistor) to buffer the bias voltage, so choosing small resistor values is no longer necessary.
But there is no schematic in the document for voltage follower using transistor.
From my understanding this is not going to work for biasing non-inverting op-amp, since we take voltage from resistor i.e. we introduce it to negative feedback loop, so we can not use large value resistors, basically making this circuit senseless - we can't save power on it, it will be almost the same as just using voltage divider(split resistor biasing).
The I tried to design my own circuit to mimic op-amp voltage follower, I came up with something like this:
The Vbias as with op-amp circuit goes to negative loop instead ground.
But this does not work, the behavior is somewhat random, signal jumps around, etc. The logic I was using is that we need to have capacitor on the output to prevent gain from changing(because we don't introduce resistors to the loop). I tried different caps and resistors values, but nothing changes, so basically my circuit is wrong fundamentally.
So the question is - how to build a Voltage Follower for biasing the negative feedback loop of op-amp? Or better said - how to do what the first circuit in this post does, but with MOSFET? Mimicking means: 1) Possibility to use large value resistors to decrease power consumption 2) Do not change the gain of non-inverting amplifier