ELECTRONICALLY TUNABLE HIGH INPUT IMPEDANCE VOLTAGE-MODE MULTIFUNCTION FILTER

Hua-Pin Chen (Taiwan), Wei Chien (Taiwan) and Chien-Ching Chiu (Taiwan)

Received September 14, 2009

Abstract

A new electronically tunable high input impedance voltage-mode multifunction filter with single input and three outputs employing two single-output current-controlled current conveyors, one differential difference current conveyor and two grounded capacitors is proposed. The proposed filter can be realized for the second-order highpass, bandpass and lowpass filter functions simultaneously without component matching conditions. The input of the filter exhibits high input impedance so that the synthesized filter can be cascaded without additional buffers. The proposed circuit employing two grounded capacitors which is very suitable to further develop into an integrated circuit implementation. The parameter sensitivities are very low and the structure does not employ external resistors thus is an active-C filter. HSPICE simulation results based on using TSMC 0.35 mm CMOS model are included to verify the theoretical analysis.

Keywords and phrases: active filters, analog circuits, current conveyors.