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What are PSPICE NMOS parameter values?

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sys_eng

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model.png

In the model editor, there are No values specified for W, L, Tox, VTO, KP, GAMMA..etc

I know you can override those values but what are their default values?

I can't seem to locate where is NMOS PSPICE model default parameter values are located.
 

There are no such "default" values.Every NMOS has its' own SPICE model parameters.
In additional to, W,L,Tox,Vto etc. are not SPICE parameters,They are physical and process dependent parameters and they cannot be used SPICE or similar simulators.
 

BigBoss said:
There are no such "default" values.Every NMOS has its' own SPICE model parameters.
In additional to, W,L,Tox,Vto etc. are not SPICE parameters,They are physical and process dependent parameters and they cannot be used SPICE or similar simulators.
Click to expand...

What?
I simulated the mbreakn transistor, if it doesn't have default process parameters then how does it behaves like a transistor? Look at mbreakn transistor model file shown with above picture, it looks like empty file.

Pspice does use those process parameters. I have a circuit text file and bring it into pspice, it does simulated
 

Here are the Spice parameters for a typical N-MOSFET, BUZ11:

.model BUZ11 VDMOS( Rg=3 Rd=5m Rs=1m Vto=3.0 Kp=9 Cgdmax=2n Cgdmin=.15n Cgs=0.8n Cjo=1n Is=2.3p Rb=6m mfg=Fairchild Vds=50 Ron=40m Qg=27n)

As you can see there are no W, L, Tox, GAMMA..etc process parameters except for Vto and Kp.
Spice does not use most process parameters nor does it recognize them if you enter them in the model.
 

crutschow said:
Here are the Spice parameters for a typical N-MOSFET, BUZ11:

.model BUZ11 VDMOS( Rg=3 Rd=5m Rs=1m Vto=3.0 Kp=9 Cgdmax=2n Cgdmin=.15n Cgs=0.8n Cjo=1n Is=2.3p Rb=6m mfg=Fairchild Vds=50 Ron=40m Qg=27n)

As you can see there are no W, L, Tox, GAMMA..etc process parameters except for Vto and Kp.
Spice does not use most process parameters nor does it recognize them if you enter them in the model.
Click to expand...

1)why does the mbreakn transistor from breakout pspice library has no SPICE parameters? It's look empty from above picture.
2)you sure PSpice doesn't use W, L parameters?? Because I change W,L on schematic and rerun the simulation, the values of the current change. Bigger W generates bigger current. So, it does looks like Pspice use W,L parameters.
 

Reading the PSpice reference manual had saved this thread.

All available MOS model parameters and their default values are listed under Analog Devices/MOSFET/MOSFET model parameters.

why does the mbreakn transistor from breakout pspice library has no SPICE parameters?
Click to expand...
Because it uses the default NMOS model. Review breakout.lib to see the mbreakn definition.
So, it does looks like Pspice use W,L parameters.
Click to expand...
Surely it does. See MOS parameter list.
 

sys_eng said:
What?
I simulated the mbreakn transistor, if it doesn't have default process parameters then how does it behaves like a transistor? Look at mbreakn transistor model file shown with above picture, it looks like empty file.

Pspice does use those process parameters. I have a circuit text file and bring it into pspice, it does simulated
Click to expand...

There should be a default values for NMOS transistor in your simulator.
Once again, Process Parameters are NOT used in SPICE or similar simulators.W and L are Physical Parameters and they are Relative to Process Parameters.
Example :Two physically identical MOS transistors have same physical parameters but their processes are different.You will get different results.

SPICE Parameters are mathematical and modeled representation with some sort of parameters of a physical device.Here W and L can be parametric but they are still related to Process Specifications.
 

FvM said:
Reading the PSpice reference manual had saved this thread.

All available MOS model parameters and their default values are listed under Analog Devices/MOSFET/MOSFET model parameters.


Because it uses the default NMOS model. Review breakout.lib to see the mbreakn definition.

Surely it does. See MOS parameter list.
Click to expand...
What Analog Devices/MOSFET/MOSFET parameters? I don't have it.

For me, anything for Pspice simulation, its C:\Program Files\Orcad\Capture\Library\Pspice.
lib.png

There's nothing under mbreakn definition except one line. .model Mbreakn NMOS
and where's NMOS defined? It's not under anywhere. It's not under breakout.lib , nor under anlg_dev.lib, none found
 

One ineffective way is to use the window explorer search on the top right and type Mbreakn.
 

CataM said:
One ineffective way is to use the window explorer search on the top right and type Mbreakn.
Click to expand...
I already found mbreakn, which is under breakout.lib.

The issue try to NMOS spice definition.
 

What Analog Devices/MOSFET/MOSFET parameters? I don't have it.
Click to expand...
The keyword in my post is PSpice reference manual. I can't believe that your are using PSpice without ever reviewing this essential document. Analog Devices/MOSFET/MOSFET parameters is referring to a specific paragraph in the reference manual.

In case the reference manual has been somehow deleted from your PSpice installation, just type in "PSpice reference manual" at google.

There's nothing under mbreakn definition except one line. .model Mbreakn NMOS
Click to expand...
That's what I said.

and where's NMOS defined? It's not under anywhere. It's not under breakout.lib , nor under anlg_dev.lib, none found
Click to expand...

NMOS is name of a the generic model. It has built-in default parameters.
 

FvM said:
T NMOS is name of a the generic model. It has built-in default parameters.
Click to expand...

Ok, got it.
So this NMOS generic model is not available for viewing then.
 

transistor curve for NMOS

transistor2.png

The transistor curve looks right. However, I do not know the transistor's W,L dimension.

and also how do I set a multiplier for a transistor. For example, 10x width of this default transistor.
 
Last edited by a moderator:

Again, if you want to know the default NMOS parameters, read the reference manual.
 

FvM said:
Again, if you want to know the default NMOS parameters, read the reference manual.
Click to expand...
It says "if L and W default not set, their default value is 100 u" . So W=100u, L=100u by default.
If I want to set 10x the width, then M=10 as multiplier.
 

sys_eng said:
It says "if L and W default not set, their default value is 100 u" . So W=100u, L=100u by default.
If I want to set 10x the width, then M=10 as multiplier.
Click to expand...
How do you know that ??? Ids is proportional to W/L ratio ( and to process dependent others ), absolute W and L values have no sense without necessary process information.
 

I agree that L and W have no physical meaning without respective other process related SPICE parameters and a geometry based model level.

It should be also mentioned that the default NMOS parameters don't make a typical transistor, e.g. regarding threshold voltage VTO of 0V.
 

BigBoss said:
How do you know that ??? Ids is proportional to W/L ratio ( and to process dependent others ), absolute W and L values have no sense without necessary process information.
Click to expand...

Because it says so in the paragraph 100u
mos.jpg
 

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