[sdiy] Differential amps and noise cancellation in dsPIC 33FJ128GP802 uP's DAC

[Ingo Debus]

> Am 05.05.2021 um 11:42 schrieb Guy McCusker via Synth-diy <synth-diy at synth-diy.org>:
> 
> though the circuit is already not perfect because the input impedances to the + and - terminals are different anyway. 

You mean the input impedances of the complete circuit with respect to ground? These are equal.
As long as the feedback works properly, both the inverting and the noninverting input of the opamp are at the same voltage. Since R5 and R7 are both 10k, a signal source connected to the left side of either R5 or R7 sees the same input impedance.

Ingo