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Image of ROHM 4th Generation SiC MOSFETs - No Negative Gate

Turning off the SiC MOSFET is also very simple with 0 V gate bias. ROHM’s latest SiC devices do not require a negative gate voltage for the OFF-state because of their high gate threshold voltage and an optimized capacitance ratio. When a bridge circuit operates at fast switching speed, the rapidly increasing drain-to-source voltage can influence the bias between gate and source. A MOSFET could be accidentally turned on and cause excessive shoot-through current losses if its gate threshold voltage is too low, or if the reverse transfer capacitance is not small enough relative to the input capacitance. Some competitor’s SiC MOSFET products require a negative gate bias for the OFF-state because the minimum threshold voltage is not high enough to prevent accidental turn-on of the MOSFET when 0 V bias is used. ROHM’s 4th Generation devices feature a high gate threshold voltage above 2.8 V, as well as a very low ratio between Cgd and Cgs capacitances. These design improvements make it unnecessary to supply negative gate voltages to the MOSFET, and thereby minimize the complexity and cost of the gate drive circuitry.

PTM Published on: 2022-06-09