Fully Digitally Programmable Generalized Mixed Mode Universal Filter Configuration

This paper presents five feature-enriched hardware-efficient mixed mode universal filter (UF) biquads using digitally programmable (DP) current conveyors (CC). Common features of proposed UFs include use of only two grounded capacitors, operation in all the four modes, realization of all the filter functions, independently programmable filter parameters and cascadability (last three features, however, are partially present in last UF). Besides all these features, the first proposed UF, designated as Generalized DPUF provides additional features such as reconfigurability, use of minimum input terminals, no component matching constraint and lesser parasitic effects. Although Generalized DPUF encompasses almost all the desirable features of any filter, it uses eight CCs for obtaining these. The need of eight CCs is justified by introducing remaining four programmable/non-programmable UFs. These additional UFs are designated as Derived UFs as they are obtained by the deletion of CCs of the Generalized DPUF. Proportionate reduction in features of Derived UFs with number of CCs proves the reasonability of eight CCs in Generalized DPUF. To further strengthen this fact, all the proposed UFs are compared with reported filters. Better/comparable performance of Generalized and reduced-performance Derived filters again justifies the need of eight CCs in Generalized UF.