Implementation of Filter Structures in VLF Band for Remote Sensing Systems Using MCFOA

This paper presents analogue current-mode filter circuits for the very low frequency (VLF) band (3–30 kHz), intended for remote sensing applications. The proposed designs include first-order low-pass, high-pass, and all-pass filters, together with a single-input, three-output universal filter providing simultaneous low-pass, high-pass, and all-pass responses. Each structure employs a single modified current feedback operational amplifier (MCFOA) and only four grounded passive components, enabling a simple and compact implementation. Designed at a cut-off frequency of 10 kHz, the filters achieve a total harmonic distortion (THD) of ≤1.5%, a dynamic range (DR) greater than 60 dB, and power consumption below 1 mW with a 2.5 V single supply. Frequency and gain can be adjusted through passive component selection. Moreover, the use of a 100 pF capacitance supports VLSI and low-voltage/low-power implementations. The proposed circuits are verified through PSpice simulations.