Electronically tunable allpass filter: linear VCO design

Abstract

A new electronically tunable allpass filter (ETAF) realization using the composite Current Feedback Amplifier (CFA) and Multiplication Mode Current Conveyor (MMCC) building blocks is proposed. First order non-minimum phase function with electronically variable output phase is derived. Extension of the filter to a linear quadrature-VCO design is then implemented. Simulation test responses of all these functions are satisfactorily verified.