Dear Sir,
Can you help verily the waveform is right? since the SR FET has resonant before SR gate turn off.
May I know the root cause induce the resonant before SR gate turn off?
It looks to me like the resonance occurs after the Vg has gone down. The FET is OFF sometime before the gate voltage reaches zero. In terms of a power circuit when the rds is 10 ohms for instance, is it OFF or ON? The frequency will give you a clue, I am guessing the output capacitance of the FET and the inductance of the secondary. The hot tip for tuning the snubber is to set R to zero and C to zero, then increase C until the ring frequency is halved. Then increase R until it looks nice, or until the peak voltage at turn off is lowest.