A single-input multiple-output voltage-mode second-order universal filter using only grounded passive components

Abstract

A new single-input multi-output voltage-mode universal filter structure with high input impedance yielding easy cascadability is proposed in this paper. The proposed filter can provide all the standard second-order universal filter responses such as low-pass, band-pass, high-pass, notch filter (NF) and all-pass (AP) responses. NF and AP responses possess low output impedances but they can be obtained through a switch. Each time, one of the NF and AP responses can be obtained. Also, other responses which do not have low output impedances can be obtained simultaneously. The proposed filter uses three plus-type differential difference current conveyors and a minimum number of only grounded passive elements, and does not need any critical passive component matching conditions and cancellation constraints; thus, it is suitable for integrated circuit process. By adding extra one DDCC+ and two grounded resistors, a universal filter with a gain is obtained. Several computer simulations using SPICE program are included to verify the theory.