The ramp current driver disclosed turns on or off power converter’s semiconductor switches with reduced electromagnetic interference (EMI). Fast switching operation of switches such as SiC metal-oxide field effect transistor (MOSFET) generates EMI. The EMI should be attenuated because it induces unexpected operation or malfunction of the other equipment. The amount of EMI is related to switching transients and the accompanying ringings on the voltage and current of the switches.
The EMI will be minimized if the wave shapes of current through the MOSFET and voltage across the MOSFET during the switching transient are controlled to have appropriate transient speed without high-frequency ringing. Driving the SiC MOSFET by ramp current in this invention controls the aforementioned wave shapes and minimizes the EMI.