Active RC networks: what benefit is there in having conjugate real zeros in the second-order transfer function?

The characteristics of a so-called real conjugate zero pair in the biquadratic transfer function are investigated and a new active RC network is provided to implement it. Different magnitude responses are obtained where the zero pair is varied while maintaining an invariant phase response. By this feature, the network can be seen as the counterpart to a phase shifter. With the aid of a simple additional circuit, the arithmetic transformation of a real conjugate zero pair into an imaginary conjugate, or into a double zero pair at the origin, is also demonstrated. This part of the network consists of operational amplifiers and resistors, each of equal value, which can be advantageously integrated. The result is an easy-to-design second-order filter section for multi-functional use.