Using Excel "Solver" for MOSFET SPICE params - diyAudio
Go Back   Home > Forums > Design & Build > Software Tools

Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th June 2013, 12:28 PM   #1
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Default Using Excel "Solver" for MOSFET SPICE params

Motivated by Pierre Touzelet's 2007 AX article for deriving Triode params with Microsoft Excel, I made a video showing how to use "Graph Grabber" and "Solver" to create basic, level 1 spice params for MOSFETs:

https://www.youtube.com/watch?v=2vh1-RbBJa0

The equations in the columns:

Id(sat) = (KP/2) * ((Vgs-vt)^2)*(1+Lambda*Vds)

where KP is mu * Cox * (W/L)

I figger "saturation" to be 90% of the current yielded at the maximum Vds for each set of Vgs curves -- and test for this. Unsaturated data is thus nulled so that no error term is calculated.

Pierre minimized "sum of the squared errors" for triodes. In the case of MOSFETs the saturation currents differ by orders of magnitude so "goodness of fit", "maximizing R-squareds" were calculated. Rather than simply letting "Solver" do its thing, you might want to manually iterate the approximations to derive params which best suit your application.
  Reply With Quote
Old 18th June 2013, 10:38 PM   #2
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
For the linear part of the curve:

Id=KP*((2(Vgs-Vto)*Vds)-Vds^2)*(1+ Lambda*Vds)

Good at first crack, but Vgs really isn't Vgs as RS gets in the way. What I've done is create an effective Vgs by multiplying the observed drain current by an approximated RS. Then let "Solver" find Vto, kappa, lambda and RS.

Now, I'm wondering if it will work!
  Reply With Quote
Old 19th June 2013, 02:44 PM   #3
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Quote:
Originally Posted by jackinnj View Post
For the linear part of the curve:

Id=KP*((2(Vgs-Vto)*Vds)-Vds^2)*(1+ Lambda*Vds)

Good at first crack, but Vgs really isn't Vgs as RS gets in the way. What I've done is create an effective Vgs by multiplying the observed drain current by an approximated RS. Then let "Solver" find Vto, kappa, lambda and RS.
First term should be: (Vgs-Vto)*Vds-(Vds^2)/2

FWIW, the datasheets and IRF's spice models don't seem to agree except for the first couple of Vgs series above Vto
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Seas Excel W22's in open baffle, need more midbass "oomph" architect7 Multi-Way 23 27th April 2013 06:15 PM
FS: Excel w15cy (x10), Peerless "XLS 8" (x4), LCY, EMU-1820M, TC2+ Archmage Swap Meet 16 12th February 2012 07:19 AM
SB Acoustics 6" Params TurboFC3S Multi-Way 15 20th February 2009 01:43 PM
FS: Seas Excel TL Home Towers "Thors" Houston/Austin pickup only kappa546 Swap Meet 15 1st September 2008 03:12 PM
Marantz imperial 7G 12" T-S params D.A.R.R.Y.L. Multi-Way 0 10th December 2004 06:51 AM


New To Site? Need Help?

All times are GMT. The time now is 05:09 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2