Power MOSFET capacitances
Yes the capacitances are small signal which is only a guide to large signal behaviour.Yes the capacitances are significant in powermosfets because after all they are comprised of millions of small signal devives called cells in paralell.The number of cells has gone up as chips became more densely packed.This means that modern low resistance powermosfets have much more capacitance than the early devices that were around in the late 1970s.In fact most powermosfets are optimised for low on resistance at the expense of capacitance these days.All the capacitances change with voltage which makes things much worse at large signals.Also the millar effect which is documented elsewhere can make gate source capacitance many times worse than the spec.Semiconductor manufacturers have realised this and state a gate charge spec which is more realistic when designing gate drive for a hard switched supply,and if you are going resonant the capacitance figure isnt too bad.