One of a critical problem in the biomedical signals measurements is hum noise activity due to power line interference. Various approaches to suppress hum noise both analog and digital techniques have been proposed. However, these approaches have some disadvantages. N-path notch filter can be an alternative solution for this problem. The notch depth in a conventional N-path notch filter is limited by the number of paths to achieve deeper notch. This paper proposes a new N-path notch filter with additional sample-and-hold (S/H) and leak buffer circuits to improve notch depth. Simulation and measurement results of 3-phase N-path filter achieve notch depth of 61.6dB and 54.5dB respectively.