Basic Filter Circuits
Allan Waters · 1991
A number of popular circuits will now be considered using the non-inverting (positive gain) and inverting (negative gain) operational amplifier configurations. In both cases, the open-loop gain of the amplifier will be taken to be high (10 5 or greater) and in the first class of circuits to be considered, the so-called voltage-controlled-voltage-source (VCVS), it will be seen that the circuit gain may be adjusted by means of a resistor ratio. In the second class of circuits where there are two feedback paths, the so-called multiple feedback (MFB) circuits, the operational amplifier is again assumed to be working as an ideal infinite gain device.