A new filtering technique for increasing the immunity of power transistors to RFI

The paper deals with the susceptibility of MOS power transistors to electromagnetic interference. The case of providing electric energy to a power load by means of a MOS power transistor connected in the low-side configuration is considered and radio-frequency interference is superimposed to the drain-source nominal voltage. The causes that lead to switch-on a power transistor driven to be switched-off (and viceversa) are highlighted and a new filtering circuit, which is inserted in the power transistor input loop, is shown. The effectiveness of the proposed filtering technique is proved by computer simulations and experimental test results.