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Active and Passive Electronic Components
Volume 17 (1994), Issue 1, Pages 21-27

Programmable OTA-Based Multifunction Active Filter

King Fahd University of Petroleum and Minerals, Box 203, Dhahran 31261, Saudi Arabia

Received 30 December 1993; Accepted 25 January 1994

Copyright © 1994 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A fully programmable multifunction filter is presented. The filter uses four operational transconductance amplifiers and two capacitors. Analog switches are used to control the filter transfer function through a microcontroller. The user is provided control over the cutoff (or centre) frequency of the filter by controlling the auxiliary bias currents of the operational transconductance amplifiers via digital-to-analog converters. The circuit can simultaneously provide three programmable transfer functions in a single structure and can realize all the standard second-order filters. The circuit is attractive for VLSI implementation.