How does the gate driver affect MOSFET switching speed?
The Miller effect produced by MOSFET CGD is what predominantly limits switching speed. A MOSFET responds instantaneously to changes in gate voltage and begins to conduct when the gate reaches the threshold voltage (VGS). To address a wide range of applications, suppliers offer a variety of power MOSFETs that transition at different gate thresholds, such as logic-level MOSFETs with lower threshold voltage. Gate waveforms indicate a plateau at a gate voltage above the threshold voltage. The amount of drive current available from the gate driver determines the MOSFET drain-voltage rise and fall times, and thus the time required to drive the gate through this plateau region.
