Based on the design fundamental of digital LDI ladder filter, a digital LDD ladder high-pass filter is designed by using the frequency transformation in this paper.

This PFC was realized by employing sliding-mode variable-structure inner current loop control and outer voltage loop PI control with digital low-pass filter to achieve high performance.

Design of digital high-pass, band pass, band-reject filter, the filter impulse response described demand as well as the filter amplitude-frequency and phase frequency response curve.