Active-C Realization of Multifunction Biquadratic Filter and Third-Order Oscillator

The paper introduces a new circuit of voltage-mode multifunction biquadratic filter employing one fully differential second-generation current conveyor, three active resistors, and two capacitors. The circuit uses metal oxide semiconductor-based active resistors instead of passive resistors to make the circuit more suitable for monolithic integration as well as to provide additional feature of electronically controllable pole frequency. Low-pass, high-pass, band-pass, and band-reject filtering functions are simultaneously realizable without need of any component matching constraints from the proposed multifunction biquadratic filter. Additionally, the nonideal aspects of multifunction biquadratic filter circuit are studied. Furthermore, a third-order dual-mode quadrature oscillator is also derived from the low-pass function of the proposed multifunction filter to check its applicability. The proposed oscillator structure makes the output current readily available from high-impedance terminals. The performance of both multifunction biquadratic filter circuit and oscillator circuit is examined with the help of HSPICE simulations.