Electromagnetic-interference (EMI) reduction techniques for power circuit designs are segmented into two categories: active and passive. Passive techniques focus on reducing the EMI level through various filtering techniques, adequate shielding, solid grounding, and proper printed-circuit-board (PCB) layout, especially for the power components.
Active methods will direct focus toward modifying the pulse-width-modulation (PWM) control signal shape to reduce EMI or spread the energy of the signal across a wide frequency range. In this article, we will look at the active methods.