how to change normal switch circuit to MOSFET circuit ?

[howk]

how to change normal switch circuit to MOSFET circuit ?

Hi!

I'm building a circuit. begin i have simulated with normal switch with pspice. but later i have with mosfets but hij does not work. I don't know how to change it? see de attachments please.

please help me.


Thanks!

 

[MikeMl]

All of your NFETs are backwards; interchange source and drain. Dont forget that to turn on an NFet, the gate must be about 2 or 3Vt higher than the source. Look up "Source Follower". The voltage across your ultimate load will never reach 5V unless every gate is driven to 8 or 9V.

You should really look into using PFets (will require inverting the gate signals).

 

[howk]

Thanks for replay. I have replaced the NFET with PFET, but not al. But there is the same problem. and found the FET of M34 always does not work. please see attachments there are the circuit and simulation result. and the output voltage must 15v, but now is 5v.

i don't know hoe can i stil do. could you help me please.

 

[MikeMl]

What are you trying to do? Some sort of charge pump?

 

[howk]

What are you trying to do? Some sort of charge pump?

thanks fot you reply. I want the circuit work as charge pump : output voltage=3 times of input voltage, but i don't know how can i stil do. could you tell me how can i resolve the problem. please.