Try to look for signal flow in the schematic. The inputs send signals thru the input impedances to the op-amp. The op-amp output sends a feedback signal thru Zf to the inverting input. Signal flow ...

The SFG is a simple circuit description that many understand. It only shows input to output signal flow. The example included a series resonant circuit, Z2, that disappeared in the SFG. Z2 is included ...

The graph below shows the total number of publications each year in Negative Group Delay Circuits and Signal Processing. References [1] Single CFOA-based active Negative Group Delay circuits for ...