The timing of the turn-on transition has three components: propagation delay, turn-on delay and rise time. The first component is the propagation delay of the driver from when the input goes high to when the GaN FET starts turning on (represented by 1 A drain current). The turn-on delay is the delay from when the FET starts turning on to when the drain voltage swings down by 20 percent. Finally, the VDS fall time is the time it takes the drain voltage to slew between 80 percent and 20 percent of the bus voltage. The drive-strength resistor value has a large effect on turn-on delay and VDS fall time but does not affect the propagation delay significantly.