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.

An example of the design procedure of the third order digital LDD ladder high-pass filter with equal magnitude response is detailed. A computer simulation of the example is given.