Pulse Generator to trigger MOSFET in PSPICE

pspice pulse generator

Hey guys,

ANy idea whats the best way to trigger a MOSfet in PSPICE..any in built function generator?i really can't use Vdc(pulse)..anything else i can use in PSPICE?thanx guys..apmreally exhausted fmr trying out with Vpulse,because its not reliable..

how to use mosfet in pspice

What is the problem with Vpulse? Can you be more specific on this? Why you want to trigger the MOST? I mean is it a part of a bigger design or you just checking characteristics?

D.

pspice vpulse

hello there,

Thanx for the replyt..actually am creating a multilevel DC Chopper. The problem is,when there's only 1 mosfet in the circuit..the triggering works fine. BUt once i add another layer..the second level that is, the triggering fails..it doesn't provide a square wave,instead a one full of distortion..so instead of an improved output DC voltage,i get a distorted one..so i was wondering,like MATLAb,does pspice have a function generator..

ps..i came across a .sym file (**broken link removed**)..but dun't understand how to incorporate in into SPICE..any idea?

thanx again

mosfet pspice

I will try to help, but I am not sure it will be adequate:

You are using the MOST as a switch? If so, in which voltage does it operate? Did you tried transmission gate instead of single n-MOS or single p-MOS?
Have you placed dummy ( MOST connected as diodes) before and after the switch?
If you do the above, your switch will work perfectly, it will be well isolated from the rest of the circuit and you will see no distortion.

Is it a VLSI circuit or a PCB circuit? Are you modelling the DC Chopper or you are creating one out of real components?

D.

how to trigger mosfet

hello dkace,

i've uploaded the pspice file.do you mind taking a look at it..i'm kind of a newbie here..

The purpose of a dummy diode is to isolate the trigger circuit and the other circuit rite??how do i place it???thanx for your time.really appreciate this..

pulse generator pspice

Hi,
I dodn't have enough time so I create a draft file with the dummy switch example and the transmission gate.

Try this configuration in your simulation and inform the outcome. This is for analog design in submicron technology but a collegue used it also in descrite and it worked.
The purpose of connecting two switches an the left and on the right of the ral switch ( not as diode as I wrongly said but as short circuit) is to divide equally the accumulated carriers omn the drain and on the surface that when MOSFET goes off, they create an undesirable current flowing through the MOST to the circuit. By applying this technique, you divide the current into two directions equaly, thus ending with a 0 effect on the circuit.
I hope it will also for your design .
D.

mosfet triggering circuit

Of course this is not a way to trigger the MOST correctly, but to ensure that you will not have parasitic effects during the operation of the circuit.
I was checking your design ; why you take the output out of the source?
You want transistors to operate in the saturation region that is why you connect drain to Vcc with no resistive load?

Can you explain your circuit a bit more ? I mean what are your intentions exactly...

D.

spice +pulse generator

hello dkace,

I did not try the design u gave..it was a bit complicated.But i've sloved the problem..once i increased the trigger voltage for the mosfet..everythign worked perfectly!!

the trigger voltage was bout 20v..I also rearranged the circuit so it wouldn't be messy!!

so now i'm trying for 5 level DC Chopper..thanx for your help!!it helped me in many ways!!wish me luck!!thanx again

pulse generator in pspice

Glad I helped, even not in this occasion. Look, The design is not complicated: The dummy MOSTs are connected as short circuit just to ensure that same ammount of charges will be directed to both sides of the switch when this is closed. SO you avoid spikes and other parasitic effect during switching off.
You are driving the gate with more than 20V ? Can you be explain some more?
Thanks for the "help me" button.
D.

triggering circuit, mosfet

hey,

i've finally understood the dummy switch method!thanx. I've uploaded the PSPICE files for you,incase it might help u in any ways. Thanx again.

Re: how to use mosfet in pspice

D.[/QUOTE]
hii, i try to on- off the n-Mosfet like switch in pspice . how i will do that? by using vpulse or function generator? is function generator is there in pspice?
please help

---------- Post added at 12:41 ---------- Previous post was at 12:37 ----------

i try to on- off the n-Mosfet like switch in pspice . how i will do that? by using vpulse or function generator? is function generator is there in pspice?
please help