Single-port miniature active damping device for differential mode EMI suppression and system stabilization

摘要

A compact 2-terminal, series-pass active damping circuit utilizing semiconductor device is proposed. It is implemented with linearly-operated device such as MOSFET using current feedback control at very low dropout voltage. The damping device features a simple internal structure and is connected in series with a generic switching mode power supply (SMPS). It can damp unwanted oscillation due to the input characteristic of SMPS as well as attenuates differential-mode noise for certain frequency range, with the merit of shrunk EMI filter. A local analogue controller is associated with the SPD, achieving robust operation while minimising the labour incurred by filter tuning process. Under variation of cable and component impedance, stable operation can still be achieved. The operating principle and theoretical analysis will be elaborated with experimental verification on a DC-DC converter.