Filter design for suppression of noise coupling from PCB to DC power supply

Based on an in-circuit measurement approach, a systematic EMI filter design procedure is developed to suppress the noise from a digital board to the power supply. The two-probe technique adopted for the in-circuit measurement allows the impedances of the power supply and the PCB to be determined under its actual operating condition. With the measured impedance information, a suitable filter topology can be selected and component value computed without any guessing.