P-type /BJT biasing to use it as Switch in Buck Converter

Submitted by Asad on

Having confusion regarding biasing of p-type BJT to use it as a switch in Buck Converter.

How does one bias and keep the voltage across Base and Emitter Vbe voltage to use BJT as  a switch? 

How does one bias and keep the voltage across Gate and Source Vgs   to use p-type mosfet  as  a switch?

How does one select the switching frequency for a particular  P-type Mosfet?

How does one select the find switching frequency of MOSFET?