P MOSFET as a switch. LTSPICE simulation

[svia]

I need some help to understand how the following circuit works.

I get that the MOSFET N when Vgs> Vgs_thereshold, Vdrain= Vs

But how does a MOSFET P works, in simplified words, as a switch?

And how this entire circuit work?


I can't get it simulating when using pulse signal and transient in LTSPICE. I should have some setup wrong, any clue?

Thanks

 

[KamW]

What does it mean "can't get simulating" LTSpice simulation don't work, or simulation is not like you want?
I am not sure what you would like to get, but in your circuit you should connect any resistor between Vout and GND - it could be very high - 10^12 or more, to allow LTSpice to calculate anything, and then see what happened.
From the first point of view I am not sure if there is diode present in FQT3P20 model, to you could see that transistor could be wrong polarised. I am not sure if you should connect S to Vout not Vpmos

 

[dick_freebird]

For starters it looks like you have the FET upside down
and it will act pretty much like a diode.