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 Help needed with model
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Jacques

Belgium
17 Posts

Posted - 14 Jun 2007 :  05:38:12  Show Profile  Visit Jacques's Homepage  Reply with Quote
I'm no Spice guru and need help with something that is probably obvious for anybody else. Sorry for the nubie question.
I want to simulate an amp with a mosfet from Sanyo. They sent me the spice model of that part.

************************ SANYO K3746 SPICE PARAMETER *************************
.SUBCKT 2SK3746 D G S
* DATE : 2007/05/09
* Temp = 27 deg
* Node1 -> Drain
* Node2 -> Gate
* Node3 -> Source

M1 1 5 3 4 M1 L=3.0E-6 W=228740E-6 AD=228740E-12
RG 2 5 9
RB 3 4 0.045

.MODEL mosfet NMOS (
+LEVEL = 7 TNOM = 27 TOX = 1.0E-07
+VTH0 = 2.70 K1 = 3.86 K2 = -0.04
+NLX = 4.70E-07 DVT0 = 3.12 DVT1 = 0.09
+DVT2 = -0.01 U0 = 600 UA = 1.04E-10
+UB = 1.00E-21 VSAT = 1.84E06 A0 = 0.66
+AGS = 1.00 A1 = 0 A2 = 1
+RDSW = 9.00E05 PRWG = 0.0E00 WR = 0.92
+WINT = 0 LINT = -7.20E-08 VOFF = 0.00
+NFACTOR = 0.64 CIT = 0 CDSC = 2.40E-04
+CDSCD = 0 ETA0 = 0.14 DSUB = 0.96
+PCLM = 0.01 PDIBLC1 = 0.10 PDIBLC2 = 1.20E-03
+DROUT = 0.96 PSCBE1 = 1.00E11 PSCBE2 = 1.00E-05
+PVAG = 0.01 DELTA = 0.03 NGATE = 1.0E19
+MOBMOD = 1 NQSMOD = 0 NOIMOD = 1
+CAPMOD = 3 XPART = 0.5 CGSO = 6.00E-11
+CGDO = 1.00E-10 CGBO = 0 CGSL = 0
+CGDL = 6.00E-09 CKAPPA = 1.20 CF = 0
+CLC = 3.0E-09 CLE = 0.8 DWC = 0
+DLC = -1.00E-06 NOFF = 3.66 VOFFCV = -0.40
+ACDE = 1.0 MOIN = 15 CJ = 2.00E-03
+MJ = 0.35 PB = 0.65 JS = 1.00E-03
+NJ = 1.30 XTI = 3.0 IJTH = 0
+KT1 = -0.6 UTE = -0.6 PRT = 3.00E06
+AT = 3.3E04 )
*
.ENDS
------------------------

My problem is : after importing the model into the spice library I receive the message :
Device 2SK3746 found in C:\Program Files\Number One Systems\Easy-Spice\support\Models\2SK3746.lb

There are errors in the circuit. Simulation aborted
*** ERROR *** Cannot find definition for MOS model 'M1'

How can I solve this ?

Another question is : While trying to solve this problem by myself, I was looking into the other libraries containing MosFet's, including some I've downloaded from manufacturers. It seems those are but remotely similar. So many parameters, and not even half of those are common to all mosfet's models. How can one be sure that EasySpice is supplied with all relevant informations ? That everything needed is taken into account and that there is nothing missing ? Especially when using manufacturer's datas ?


Jacques Casier
ACDC sprl, Brussels

"If it ain't broken, don't fix it" ... I should remember this !

Peter Johnson

United Kingdom
459 Posts

Posted - 14 Jun 2007 :  11:33:21  Show Profile  Visit Peter Johnson's Homepage  Reply with Quote
Actually, this is quite an easy thing to do. Firstly, pick an appropriate MOSFET from the Easy-PC libraries, and put it in your circuit. The only important detail is that it needs to have exactly 3 connections.

Now the clever bit. Add these values:
SpiceDevice=X
SpiceModel=X2SK3746
SpicePinOrder=D G S

Normally for a MOSFET, the device type would be 'M', but as the Spice model clearly describes it as a subcircuit (that is, a composite of other models), the device type is 'X'. (And this is why the model isn't being found. At present it's looking for a device of type 'M' not 'X'.)

Secondly, the model is a 2SK3746, but as Spice models are required to start with a letter, the convention is to start any numerical parts with the device letter, in this case an 'X'.

Finally, the pin order is listed on the first (non comment) line of the model as D-G-S, so the same list is applied to the Easy-PC component. You do need to use the actual Easy-PC pin names here. With a different component, the value could easily have read as:
SpicePinOrder= Drain Gate Source

It's the equivalent name that's important. i.e, don't use 'CK' if the Easy-PC pin name is 'Clk' and so on. It IS case sensitive.

As you can see from the above information, it's not the component name in Easy-PC that matters, just the values that have been added to the component to link it to a specific Spice model.

Don't worry about the apparent differences between models for similar devices. The manufacturers do have a lot of experience with Spice models, and it's in their interest to keep the simulation accurate, so based on that experience they'll pick the best way to simulate any device.
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Jacques

Belgium
17 Posts

Posted - 16 Jun 2007 :  05:18:18  Show Profile  Visit Jacques's Homepage  Reply with Quote
Reading your answer, I thought I had understood, but obviously I have not. It still doesn't work.

Questions :
- Using the line
.SUBCKT 2SK3746 D G S
in the model file, is it valid ?

- I already had the lines
SpiceDevice=X
SpiceSubcircuit=2SK3746
SpicePinOrder=D G S
as parameters in my mosfet component.

Adding the line
SpiceModel=X2SK3746
still gets me the <Cannot find definition for MOS model 'M1'> message although I have the <Device 2SK3746 found in C:\Program Files\Number One Systems\Easy-Spice\support\Models\X2SK3746.mod> line in the Simulator dialog box.

As side notes :
I cant seem to be able to remove the SpiceSubcircuit parameter.
I use the NMOS 3 term model from the Spice library.





Jacques Casier
ACDC sprl, Brussels

"If it ain't broken, don't fix it" ... I should remember this !
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Peter Johnson

United Kingdom
459 Posts

Posted - 18 Jun 2007 :  05:43:29  Show Profile  Visit Peter Johnson's Homepage  Reply with Quote
I think we're going to have to check your design. Would you email a copy to me at <support@numberone.com> please?
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