1. Home
  2. Electronics Design
  3. Explanation of SPICE Parameters

Explanation of SPICE Parameters

I can't find any useful references for MOSFET SPICE parameters. Does this information exist entirely in book form, or something?

Example: websites copypasting the SPICE 3f5 handbook. This says more-or-less what the parameters are (e.g., doping density of so-and-so, etc.), but not how they're used, what they do (no formula, no description, no intent). Even the ones that do (e.g., HSPICE manual gives some equations) have gaps between equations, and nothing explained. I certainly haven't seen anything that says functionally what the parameters relate to, in the V/I/time/temp characteristics of the resulting device.

Also no explanation of why LAMBDA doesn't exist in LEVEL=3, even though all manuals put it in the list of "these parameters apply to _all_ LEVEL=1,2,3,6 models". Also, parameters are hit and miss between all the flavors and makes of SPICE. Just fantastic.

Adjusting the parameters one by one, I can't seem to find anything that doesn't simply shift the DC transfer curve up or down (in terms of current), left or right (equivalent to a change in VTO), or skew it (NFS appears to be the only parameter that actually causes subtreshold conduction in LEVEL=2,3).

No single parameter softens the drain output curves (the transition between triode and linear ranges), or causes Gm to drop at high current (analogous to BJT hFE degredation at high current). IIRC, these were the reason for creation of the JFET + MOS model, which is sometimes seen.

Tips?

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
Website: http://seventransistorlabs.com
Reply to
Tim Williams
Loading thread data ...

Rs?

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

you'll have to google around a bit. each different simulation model (level=) usually has some associated paper or something wot explains it. (that doesn't mean you or I will understand it tho')

Reply to
Johann Klammer

Perhaps:

"Operation and Modeling of the MOS Transistor" Yannis Tsividis, Colin McAndrew Oxford University Press, 2011 ISBN 978-0-19-517015-3

My PSpice documentation shows Lambda in Level=3 equations

Subthreshold behavior was not ever modeled adequately until PSpice Level=5 (or was it Level=6 ;-)

The transition "bump" from triode to linear regions was fixed (in PSpice numbering) going from Level=5 to Level=6. I don't know the equivalent numbering in HSpice... perhaps 27->28?

Did you vary ALL parameters ?:-)...

.MODEL nch_16 NMOS ( LMIN = {1.000E-05-dxln} LMAX =

20.001e-006
  • WMIN = {1.0000E-05-dxwn} WMAX =
900.001e-6 +LEVEL = 7 TNOM = 25.0 VERSION = 3.2 +TOX = {toxn} TOXM = {toxn} XJ = 1.6000000E-07 +NCH = 3.9000000E17 LLN = -1 LWN = 1.0000000 +WLN = 1.0000000 WWN = 1 LINT = 1.0000000E-08 +LL = 0.00 LW = 0.00 LWL = 0.00 +WINT = 3.0000000E-09 WL = 0.00 WW = 0.00 +WWL = 0.00 MOBMOD = 1 BINUNIT = 2 +XL = {-0.02E-6+dxln} XW = {0.0+dxwn} DWG = 0.00 +DWB = 0.00 ACM = 12 LDIF = 9.00E-08
  • RSH = {rshn} RD = 0
+RS = 0 +VTH0 = {0.4365561+dvthn} WVTH0 = {0+dwvthn} PVTH0 = {0+dpvthn} +K1 = 0.5142301 K2 = 1.4797844E-02 +K3 = 0.00 DVT0 = 0.00 DVT1 = 0.00 +DVT2 = 0.00 DVT0W = 0.00 DVT1W = 0.00 +DVT2W = 0.00 NLX = 0.00 W0 = 0.00 +K3B = 0.00 VSAT = {9.0000010E04+dvsatn} +UA = -6.1227400E-10 UB = 2.3135539E-18 UC = 1.0876087E-10 +RDSW = 1.7000000E02 PRWB = 0.00 PRWG = 0.00 +WR = 1.0000000 U0 = 4.2203390E-02 A0 = 0.3700794 +KETA = 9.2634850E-03 A1 = 0.00 A2 = 0.9900000 +AGS = 2.0000000E-02 B0 = 0.00 B1 = 0.00 +VOFF = -0.1405780 NFACTOR = 1.0000000 CIT =

-1.0000001E-04

+CDSC = 0.00 CDSCB = 0.00 CDSCD = 0.00 +ETA0 = 5.0000000E-05 ETAB = -5.0000000E-05 DSUB = 0.00 +PCLM = 0.8000001 PDIBLC1 = 1.0000000E-06 PDIBLC2 = 6.9999990E-04 +PDIBLCB = 1.0000000E-02 DROUT = 0.00 PSCBE1 = 2.0000003E08 +PSCBE2 = 1.0000000E-06 PVAG = 0.00 DELTA = 1.0000000E-02 +ALPHA0 = 0.0 ALPHA1 = 0.448150714 BETA0 = 11.59263 +KT1 = -0.2240464 KT2 = -3.0266136E-02 AT = 2.0000000E04 +UTE = -1.5799998 UA1 = 1.2240000E-09 UB1 =

-1.1209314E-18

+UC1 = 1.1643822E-11 KT1L = 0.00 PRT = 0 +CJ = {cjn} PB = 0.6882682 MJ = 0.3595262 +CJSW = {cjswn} PBSW = 0.6882682 MJSW = 0.2003879 +CJSWG = {cjswgn} PBSWG = 0.6882682 MJSWG = 0.43879 +CGDO = {cgon} CGSO = {cgon} TCJ = 0.001040287 +TCJSW = 0.000645489 TCJSWG = 0.000645489 TPB = 0.001554306 +TPBSW = 0.001554306 TPBSWG = 0.001554306 +JS = 3.50E-07 JSW = 1.45E-12 NJ = 1 +XTI = 3 CAPMOD = 3 NQSMOD = 0 +XPART = 1 CF = 0 TLEV = 1
  • TLEVC = 1 CALC ACM= 1 SFVTFLAG =
0 +DLC = 3E-9 LLC = -0.039 NOIMOD = 2 +NOIA = 2.00E19 NOIB = 1.2E04 NOIC = 2.5E-13 +EM = 3.0E07 EF = 0.874 ) ...Jim Thompson 
--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website. 

Thinking outside the box...producing elegant & economic solutions.
Reply to
Jim Thompson

Does this help any?:

formatting link

From Andrei Vladimirescu, The Spice Book

Reply to
Klaus Kragelund
[snip]

Just a few pages >:-}....

...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

formatting link
| 1962 |

I'm looking for work... see my website.

Thinking outside the box...producing elegant & economic solutions.

Reply to
Jim Thompson

Better resolution:

formatting link

Reply to
Klaus Kragelund

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

I need 3f5 compatible parameters.

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
Website: http://seventransistorlabs.com
Reply to
Tim Williams

Well, no. "Nice copy right"?

Also, MOS, not BJT.

Did find this,

formatting link
which has been helpful.

It's still not clear what the parameters and interactions are, but I seem to have done a satisfactory job. The remaining quirks are:

- Triode-to-linear piecewise discontinuity

- Subthreshold to strong inversion piecewise discontinuity (Gm peaks at the transition, slow clap)

- Weird Gm profile, including sharp peak in the middle of operation (around Idmax) and sharp reduction at Idm (doesn't seem to be any way to accomplish this; I'm ab/using triode region to make it look alright at low voltages at least)

- Output conductance can't be made high enough with LAMBDA (LEVEL=2)

Which mostly seem to be limitations of the model itself, and also quirks of the device in question, which is very different from the kind of MOS they wanted to model in the first place.

Plus, I now seriously doubt that any manufacturer has ever produced a model of this type (i.e., primarily using SPICE primitives) that's more than ballpark accurate to the real part. So I'm calling it good.

And that's just forward DC parameters...

But I have a pretty good idea what I need to make realistic capacitors, so that shouldn't be so bad. Unsure about body diode and recovery. I should maybe build a test circuit for that, or just ignore it entirely...

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
Website: http://seventransistorlabs.com
Reply to
Tim Williams

So contact Berkeley...

Although it appears that 3f5 is obsolete. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website. 

Thinking outside the box...producing elegant & economic solutions.
Reply to
Jim Thompson

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.