Canonic unity-gain complex-pole all-pass/symmetrical-notch RC active networks

A method of enhancing the selectivity of a class of RC active all-pass/notch networks is presented which requires the addition of only a buffer amplifier and a simple resistive attenuator. Sensitivity considerations show that the resulting canonic structures are not suitable for high Q factor applications but are relatively insensitive to variations in the amplifier gain-bandwidth products. The proposed networks require a minimal design effort, have a unity gain constant, utilize equal capacitors and possess a low-impedance output.