A Zero-Crossing Approximation of a Distorted Sinusoidal Signal Using Analog Circuit

This paper proposes a method for zero-crossing approximation of a band-limited sinusoidal signal embedded by a white Gaussian noise-like distortion. It consists of passive low-pass filter and dynamic-hysteresis comparator circuits. Simplicity and wide dynamic range are the main goal of the proposed approach. Theoretical calculations were formulated to select proper circuit components values. Simulation and experimental results are then presented to show circuit performance and characteristics. The method approximates zero crossing within a certain boundary of small phase-shifts around the crossing signal. It utilized over a wide range of input amplitude and frequency variations.