I have a very space and power constrained application, where I want to apply a twin-T notch filtering to an audio signal and add a little gain of about ~10x.
The following filter section has the desired frequency response (a widish deep notch at ~1 kHz):
The problem is that my signal source has a rather high output impedance of ~20 kOhm, and that my signal sink has a rather low input impedance of 10 kOhm. So, I need buffering.
I am now trying to implement this functionality using a single op-amp like so:
The impedances Z1 and Z2 could be networks of resistors and capacitors to create an inverse notch filter function, i.e. a pole-like response. My intuition tells me that this should be possible, but I struggle to create it.
Is such a feedback network possible, that will lead to the same response as the dual op-amp version above? Maybe by using some inverting amplifier form or a hybrid of inverting and non-inverting (as long as input impedance permits).