Fully Differential Current-Mode Configuration for the Realization of First-Order Filters with Ease of Cascadability

Abstract

It is well known that fully differential signal processing is more advantageous than single-ended signal processing in a noisy environment, and is widely used in audio, video and other signal processing applications. This paper introduces a new fully differential configuration that contains a first-order low-pass (LP) filter, high-pass (HP) filter, and all-pass (AP) filter, all present within the same circuit design. The proposed fully differential configuration is simple and employs only one multiple-output current differencing transconductance amplifier and one grounded capacitor. The circuit has a wide operating frequency range (up to 73 MHz). The additional features offered by the proposed circuit include use of the lowest number of active and passive components, suitability of the integrated circuit chip, support of cascadability, electronic tunability, no passive component-matching restrictions, availability of all first-order responses, i.e., LP, HP, and AP, and low-level operating supply voltages. Non-ideal and parasitic analyses are investigated for the proposed circuit, and PSPICE simulation results are presented to verify the proposed theory. Additionally, the proposed fully differential LP filter circuit is experimentally verified using off-the-shelf ICs. Moreover, the cascading feasibility is demonstrated by realizing a fully differential nth-order LP filter.