Noise Reduction and Dynamic Range Enhancement of Pulse-Driven GMI Sensors via Optimized Anti-Aliasing Filtering

Abstract

  This study proposes a method for enhancing the dynamic range of pulse-driven Giant Magneto-Impedance (GMI) sensors through optimized anti-aliasing filtering. Aliasing noise, identified as the primary limitation, is effectively suppressed using a low-pass filter with a carefully selected cutoff frequency that maintains the sensor’s bandwidth. Introducing an anti-aliasing filter with 𝑓_C = 31.2 MHz reduced circuit noise by approximately 58%, yielding a 6 dB improvement in dynamic range. Additional enhancement was achieved by replacing the buffer amplifier with a low-noise ADA4899, which further reduced the 10-Hz noise floor by 58%. Although amplifier noise was mitigated, residual noise from excitation pulses and sampling jitter remained. These results confirm that systematic noise analysis and filter optimization substantially improve GMI sensor performance, supporting their applicability to highly sensitive measurements such as biomagnetic field detection in the picotesla range.