High speed high power 555 PWM

Remembering this is a simulation and all values are ideal numbers plus ground is as much ground can be, there may be need for some filtration on the output if true DC is desired. Also, full integration is better but this works quite well. Transistors Q3 & Q4 should be able to satisfy needed parameters to drive the N-MOSFET in desireable timing and ranges for optimal RDSon. Basically, match impedance for your FET and you will achieve good efficiency.