EMI filter using active damping with frequency dependant impedance

摘要

A circuit for providing damping in an electromagnetic interference (EMI) filter with an inductor-capacitor (LC) circuit, includes at least one capacitor 20 connected to received a common-mode current from the LC circuit; a current sensor 26 that senses the common-mode current; a linear amplifier 28 that amplifies the sensed common-mode current; and a power amplifier 30 that receives the amplified sensed common-mode current and outputs a voltage which creates a damping impedance for frequencies of the common-mode current less than a threshold frequency and absorbs the common-mode current for frequencies greater than the threshold frequency.