ACTIVE COMMON MODE EMI FILTER, INCLUDING SERIES CASCADED FILTER WITH REDUCED POWER DISSIPATION AND TRANSISTOR VOLTAGE RATING

摘要

An active filter comprises a transistor stage, a current sensor (transformer) coupled to a branch of a circuit having a common mode noise current flowing therein and a capacitor coupled between the transistor stage and a ground return line from a load. The transistor stage includes two transistors ( Q1, Q2) driven by an output of the current sensor (transformer). The current sensor (transformer) and the transistor stage are coupled in a feedforward arrangement. The filter may comprise a plurality of the transistor stages coupled in series for reducing power dissipation and transistor voltage rating.