I don't see how ferrite beads will prevent this. The Miller capacitance is internal to the device and no amount of ferrite beads will mitigate it.
Yes however the sharp current spikes caused by this charging up are finding their way onto the gate and through the current sense resistor, if I can squash these spikes a bit then that would be great. The miller capacitance still needs a loop to complete and that would mean a current path involving at-least two MOSFET leads.
Usually ferrite beads go onto the gate terminal but their primary use is it to kill RF oscillations (often caused by sharp turn on.)
Leo
There is a bit of that during turn off well into the Mhz range, but just putting one on the gate would still leave the drain to source capacitance open to sharp pulses which goes through the current sense resistor.
...very fast spikes as they are coupling into the gate and current sense resistor via miller capacitance.
Could you re-phrase this? It's not very clear where the spikes are coming from if they are coupling to both gate and wherever current sense shunt is.
Leo
They come from the primary coil and LCD snubber, there is a small RCD snubber too but the main one is the LCD since several amps flow through the primary at low and its driving a LOPT so that big hv drain pulse is needed. Its well below the MOSFET breakdown voltage but the LCD snubber does make it very ringy as it cycles through its phases.
My aim is to reduce or eliminate miller induced spikes on the gate turning it back on slightly as it reaches just above the turn on threshold, and also to reduce the big spikes on the current sense resistor ramp waveform. Right now they are very fast and cross the threshold where the UC3844 does its thing.
The circuit actually works ok but just this funny business on the gate and current sense resistor is making me want to fix it.