Texas Instruments Incorporated
ACTIVE ELECTROMAGNETIC INTERFERENCE (EMI) FILTER FOR COMMON-MODE EMI REDUCTION

Abstract:

A system includes a conductive chassis having a first ground terminal. The conductive chassis couples to a switching circuit having a second ground terminal and having a first switching frequency. The second ground terminal is electrically isolated from the first ground terminal. An active electromagnetic interference (EMI) filter has an output and first and second inputs, and is configured to receive a first AC voltage having a second switching frequency at the first input, receive a second AC voltage having the second switching frequency at the second input referenced to the first ground terminal, sense noise having the first switching frequency on at least one of the first or second inputs, and generate an injection signal at the output based on the detected noise. The output couples to at least one of the first or second inputs.