# How to make tests circuits for typical characteristics for a mosfet?

Hello,

For example let’s take this n-channel mosfet: Si7336ADP - it is just as example.

How to make tests circuits for typical characteristics. We can start with below graphs:

This is the model (taken from LTspice library):

.model Si7336ADP VDMOS(Rg=3.5 Rd=1.2m Rs=800u mtriode=1.9 lambda=0.01 Vto=2.9 Ksubthres=100m Kp=280 Cgdmax=1.6n Cgdmin=200p A=1.5 Cgs=5.2n Cjo=3n M=.5 Is=5p Rb=3m mfg=Siliconix Vds=30 Ron=2.4m Qg=36n)

I want to know how I can generate above graphs in simulation with the above mosfet, this is the idea.

Something is strange here? Sorry for LTspice (and not QSPICE) simulation right now.

an-pj1003.pdf (2.1 MB)

You may get the idea on how those parameters are measured in this article I wrote for my former employer…

Yeah, it is good to have more details, but I am more interested to have simulation running for an example to see concretly how these things can be simulated in simulation environment.

This is a Qspice example to get Ciss, Crss and Coss from NMOS.
Mathematic formula may be more direct with .func as compare to H-source

NMOS Ciss Coss Crss.qsch (6.7 KB)

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Thank you Kelvin.

Now, for these 2 graphs, how circuit simulation will look like?

Idea is that I want to have simulation circuits for all the graphs (or for as many as possible graphs or for all the relevant graphs) from typical characteristics shown by the datasheet.

I think you got this figure incorrect, as @bordodynov example is a PMOS example but your device is a NMOS. This is the PMOS setup which replicate example quoted by bordodynov.

PMOS Ciss Coss Crss.qsch (6.9 KB)

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This is to simulate Rds(on) vs Drain Current (Id)

NMOS Rdson vs Idrain.qsch (3.4 KB)

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This can simulate gate-to-source voltage vs gate charge (Qg). But practical circuit possibly not construct in this way.

NMOS Vgs vs Qg Gate Charge.qsch (4.1 KB)

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Kelvin:

This plot basically is quite straight forward. Only trick is that temperature requires to use `.temp` or `.step param TEMP`

NMOS Isource vs Vsd.qsch (2.9 KB)

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Thanks Kelvin. I will post some more (remaining) graphs tomorrow from this mosfet datasheet (these are somehow easier, but maybe you will include all of them in your open documentation for QSPICE and therefore it would be good to have as many as possible circuit simulations for as many as possible characteristics of mosfets founded in the mosfets datasheets. I will search through other mosfets datasheets to see other graphs, apart from these so far.

@Cornel
I upload a pdf and all its related .qsch into this Github link.
However, as Mike is still working on to fix a minor bug, I expect document will be modified later. But currently, should give you enough hint how to do all these basic plots.

KSKelvin-Github : Datasheet Typical Characteristic

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BUK9Y8R7-60E.txt (2.1 KB)

In datasheet of BUK9Y8R7-60E:

From where could come the difference? The model to have problems?