Multiple-Input Multiple-Output Universal Filter Using DDTAs

This paper presents a multiple-input multiple-output universal biquadratic filter using differential difference transconductance amplifiers. The variant filtering responses can be obtained by appropriately applying input signals and appropriately choosing output terminals. The voltage-mode filter possesses both high-input and low-output impedances. The proposed filter provides five standard filtering responses. The natural frequency can be controlled electronically, and the quality factor can be controlled orthogonally. The performance of the proposed filter is confirmed using PSPICE simulation based on 0.18 µm CMOS technology from TSMC.