A Current-Mode Nth-Order Multifunction Filter Using Minimum Number of DVCCs

In this paper, a nth-order current-mode universal filter based on differential voltage current conveyors (DVCCs) is proposed. Using minimum number of passive Components, The filter obtained from the proposed structure can simultaneously realize low-pass, band-pass, all-pass, high-pass and band-reject responses by choosing appropriate input branches without changing the passive elements. The obtained nth-order filter is only composed by n DVCCs and n capacitors and n resistors. All capacitors and resistors are grounded, which is integrated conveniently and is compatible with VLSI technology. The proposed filter requires no active and passive element matching conditions and/or cancellation constraints. Additionally, a universal biquadratic filter as an example is introduced. The second-order filter has low active and passive element sensitivities, and offers orthogonal control of the angular resonance frequency (ω_o) and quality factor (Q). HSPICE simulations are performed employing 0.18 μm CMOS process and the performance simulation results are tested by comparing with the theoretical results of the filter.