Filter cirucit realization with single operational amplifier and LCR elements and its application for allpass response

This paper discusses a method for configuration of a single operational amplifier filter circuit using one operational amplifier (Op Amp) and LCR elements. the proposed single Op Amp filter cirucit has a constant resistance input impedance and a zero output impedance. It allows realization of any stable transfer function. In this paper, a method for realizatio of an allpass function in investigated in particular and its design method is presented. Actually, a computer simulation and an experiment with a test circuit made of discrete components are carried out for a cirucit to realize a fifth-order allpass function. the cirucit performance is compared with that of a cascaded scheme of Deliyannis circuits. the element sensitivity in regard to the LCR elements, the frequncy characteristics of the Op Amp and the sensitivity of the inductor L with respect to Q are derived. It is shown that the proposed allpass circuit has low element sensitivity and the number of necessary reactance elements is identical to the order of the transfer function.