Gate Resistor
It is the small-value series resistor placed between the gate driver and the MOSFET gate. It determines how fast the gate capacitance charges and therefore the switching time. It is typically chosen between 2 and 47 Ω: a small value lowers the loss but increases the noise, a large value does the opposite.
Although the gate resistor is a simple current-limiting device, it is one of the most delicate balance points of driver design. If you reduce its value the gate charges quickly, the transition time shortens and the switching loss falls. But at the same time the rate of voltage change (dv/dt) and the rate of current change (di/dt) at the drain terminal grow; this in turn increases the radiated noise, the spikes formed across the cable inductance and the ringing.
If you increase its value the edges soften and EMI falls, but the MOSFET stays longer in the transition region and the switching loss increases. In typical applications the range of 2–47 Ω is used; it is also common to have a diode in parallel with the resistor in order to give different values for turn-on and turn-off.
In the field you do not adjust this directly, but you live with its consequences. If the noise coupled to the RF receiver through the motor cable persists despite the use of short cable and well-twisted pairs, the source is most often the edge speeds of the power stage. In that case the solution is the wiring arrangement and ferrite/capacitor suppression.
The context in which this term is used: DC Motor Driver Selection Guide