3 FILTER CIRCUITS
A high pass filter can be formed by placing a capacitor in series with an inverting gain stage as shown in Figure 4:
Reference 5 describes the MFB topology in detail.
There is no reason why the feedback paths have to be identical. A bandpass filter can be formed by using nonsymmetrical feedback pathways (one low pass and one high pass). Figure 7 shows a bandpass filter that passes the range of human speech (300 Hz to 3 kHz).
3.2.2 Akerberg Mossberg Filter