I need to PWM a mosfet at a maximum frequency of 200 KHz, and I'm aware that at those speeds "gate ringing" becomes an issue. From what I've seen, it's customary to include a small value resistor (about 10 ohms or so) between the driver and the FET's gate in order to limit inrush current into the gate. I've also learned that it's also good practice to place an inverse parallel diode with said resistor to minimize the gate's discharge time ... these last points are important only at high switching frequencies, and become insubstantial at low frequencies.
My specific questions are:
My specific questions are:
- Why is ringing an issue? Would "false triggering" or "stuttering" during turn-on happen in extreme cases?
- What's the main cause behind said ringing? Is it only the FET's gate capacitance or is there some other mechanism involved?
- What would be the best way to simulate a specific FET's gate in LTSpice? That is, would it be too hard to build a small circuit in the simulator that would behave exactly as a FET's gate? Never mind the switching side of the FET for now, at this point I'm only interested in correctly exciting its gate.