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How to find the value of beta = (mu*Cox)(W/L)/2 of MOSFET in ngspice

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rkrupa

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How to find the value of beta = (mu*Cox)(W/L)/2 of MOSFET in ngspice? Is there any command that displays that? The show command displays many parameters but doesnt display beta's value. Is there any other way by which we can find accurate value?

Here is my model file:

Code: 
.MODEL NMOS NMOS LEVEL = 49
+VERSION = 3.1 TNOM = 27 TOX = 5.8E-9
+XJ = 1E-7 NCH = 2.3549E17 VTH0 = 0.3551677
+K1 = 0.4881677 K2 = -1.465714E-6 K3 = 1E-3
+K3B = 3.2222493 W0 = 1E-7 NLX = 1.927361E-7
+DVT0W = 0 DVT1W = 0 DVT2W = 0
+DVT0 = 0.5751286 DVT1 = 0.5660833 DVT2 = -0.3026132
+U0 = 305.8066794 UA = -1.152667E-9 UB = 2.42808E-18
+UC = 4.12734E-11 VSAT = 1.287591E5 A0 = 1.7957675
+AGS = 0.359392 B0 = 1.272642E-10 B1 = 4.171173E-9
+KETA = -9.762332E-3 A1 = 4.569146E-4 A2 = 0.531924
+RDSW = 175 PRWG = 0.15 PRWB = -0.1243425
+WR = 1 WINT = 0 LINT = 2.8E-9
+XL = 0 XW = -4E-8 DWG = -1.5E-8
+DWB = 2.37129E-9 VOFF = -0.1090174 NFACTOR = 1.5319983
+CIT = 0 CDSC = 2.4E-4 CDSCD = 0
+CDSCB = 0 ETA0 = 6.182294E-3 ETAB = 2.692579E-4
+DSUB = 0.0454551 PCLM = 1.6205616 PDIBLC1 = 0.9594821
+PDIBLC2 = 2.748496E-3 PDIBLCB = -0.0220856 DROUT = 1
+PSCBE1 = 6.837438E8 PSCBE2 = 2.319772E-4 PVAG = 9.53415E-3
+DELTA = 0.01 RSH = 3.8 MOBMOD = 1
+PRT = 0 UTE = -1.5 KT1 = -0.11
+KT1L = 0 KT2 = 0.022 UA1 = 4.31E-9
+UB1 = -7.61E-18 UC1 = -5.6E-11 AT = 3.3E4
+WL = 0 WLN = 1 WW = 0
+WWN = 1 WWL = 0 LL = 0
+LLN = 1 LW = 0 LWN = 1
+LWL = 0 CAPMOD = 2 XPART = 0.5
+CGDO = 4.57E-10 CGSO = 4.57E-10 CGBO = 1E-12
+CJ = 1.556442E-3 PB = 0.99 MJ = 0.4227041
+CJSW = 4.217952E-10 PBSW = 0.9814315 MJSW = 0.1974203
+CJSWG = 3.29E-10 PBSWG = 0.8515942 MJSWG = 0.2684911
+CF = 0 PVTH0 = -6.690647E-3 PRDSW = -8.4
+PK2 = 1.959318E-3 WKETA = 3.50257E-3 LKETA = 8.792764E-4
 
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mu is U0 from your model file

Cox = εSiO2*ε0/TOX
where εSiO2 = 3.9 and ε0 = 8.854e-12 As/Vm, and TOX is from your model file

εSiO2*ε0 = 34.5 aF/µm

W and L are width and length of the transistor, i.e. of its channel.
 
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    rkrupa

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This is all fine but to me, probably secondary to a real
interest such as drive strength ratio about the SRAM
cell "tipping point" or some such. And that, in modern
technologies, can be far from the classical form you'd
calculate from model params.

I'd favor a circuit simulation result from a blessed set
of models, over a simplified calculation that ignores
many known actors.

But maybe you are constrained to an approach by
things other than realism and practicality.
 

Sure you're right for any practical purpose, but I guess it's simply educational, to understand the basics.
 

Thanks so much. How did you figure it out? Is there any wesbite or manual where these symbols used in model file are given? Also, is there any place where I could get model files?

Krupa
 

See any of these Analog Circuit Design Textbooks.

Model files you get from the fabs/foundries which model their products and give them to registered members who buy and use their products - or - for educational purpose - e.g. from PTM.
 
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    rkrupa

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