N-path notch filter with a 43-dB notch depth improvement for power line noise suppression

Power line noise is one of critical problems in bio-sensing. Various approaches utilizing both analog and digital techniques has been proposed. However, these approaches need active circuits with wide dynamic range. This paper proposes the use of N-path notch filter as a power line noise filter. However, the notch depth in a conventional N-path notch filter is limited by the number of path. A new N-path notch filter with additional sample-and-hold (S/H) circuit is proposed. Simulation results show that the additional S/H circuit improves the notch depth by 43dB.