DESIGN AND FABRICATION OF A NARROW BAND SIGNAL PROCESSING CIRCUIT FOR 380 HZ MAGNETIC FIELD SENSING APPLICATIONS

Abstract

This paper presents the design and fabrication of a narrowband analog signal processing circuit tailored for magnetic field sensing applications centered at 380 Hz. Given the frequency’s proximity to common industrial electromagnetic noise yet outside typical power-line harmonics, the proposed circuit aims to enhance selectivity and signal integrity in low-frequency measurement environments. The system comprises a cascaded structure including a preamplifier, a 50 Hz notch filter, high-pass and low-pass filters defining a 370 - 390 Hz band, a narrow band-pass filter centred at 380 Hz, a gain stage with a factor of 14, and a Schottky-diode-based full-wave rectifier for AC-to-DC conversion. Experimental validation using function generator inputs and oscilloscope measurements demonstrates the system’s ability to suppress out-of-band interference, maintain a high signal-to-noise ratio, and preserve amplitude fidelity. The results suggest that the low-power, compact, and modular design is well-suited for integration into embedded magnetic sensing systems operating in electromagnetically noisy environments.