Effects of amplifier imperfections in a particular RC-active circuit

The performance of a particular RC-active circuit, using a modified parallel T with unity-gain amplifier, is analysed on the assumption that the amplifier is ideal. Approximate expressions are then derived which enable the effects of finite input impedance, nonzero output impedance and nonzero source impedance to be calculated. It is shown that some of these effects can be reduced in magnitude by the use of an infinite-gain, instead of a unity-gain, amplifier, and that a further improvement is possible by using the two types of amplifier together in one circuit. The analysis is extended to cover these two arrangements.