The design and gain bandwidth dependence of a class of single amplifier second-order all-pass RC active networks

The design of second-order all-pass filters is considered for the class of RC active networks consisting of two passive subnetworks (one being purely resistive) and a single differential input operational amplifier. It is shown that many alternative all-pass filter structures can be devised using three basic RC passive subnetworks. Design formulas are presented which minimize the phase error arising from the finite and complex nature of the amplifier gain and enable a meaningful comparison of the alterna. tive structures to be made.