CMOS Realizable and Highly Cascadable Structures of First-Order All-Pass Filters

Two novel resistorless structures of a first-order voltage-mode all-pass filter are presented in the paper. Both the structures employ a fully differential second-generation current conveyor (FDCCII) as the primary active element, in addition to an active resistor. A grounded capacitor is the only passive component used in both the structures. In both the structures, CMOS realization of FDCCII is utilized; hence, these structures are CMOS compatible. Some of the other highly demanded features possessed by the presented all-pass structures are: a simple circuit topology, electronic tunability, high input impedance, constraint-free operation in terms of passive component matching, and low sensitivity figures. The theoretical performances under ideal and non-ideal scenarios are presented in detail. Furthermore, the proposed idea is extended to an Nth-order voltage-mode all-pass filter and a quadrature oscillator to explore some of the possible applications. PSPICE simulation results verify the theoretical claims of the presented all-pass filters. HIGHLIGHTS Two novel resistorless structures of first-order all-pass filters based on fully differential second-generation current conveyor are presented Performance of the proposed structures are thoroughly described in ideal and non-ideal scenarios Theoretically described details of the proposed structures are verified by carrying simulations on PSPICE using 180 nm CMOS technology An Nth-order all-pass filter and a quadrature oscillator are also presented as applications GRAPHICAL ABSTRACT