Using Excel "Solver" for MOSFET SPICE params
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 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
 15th June 2013, 01:28 PM #1 jackinnj   diyAudio Member     Join Date: Apr 2002 Location: Llanddewi Brefi, NJ 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.
 18th June 2013, 11:38 PM #2 jackinnj   diyAudio Member     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!
jackinnj
diyAudio Member

Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Quote:
 Originally Posted by jackinnj 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

 20th April 2015, 11:09 PM #4 aymo0003 diyAudio Member   Join Date: Dec 2011 Thanks for the work. I'm looking into using this for another FET; would you be able to attach or post a link to the spreadsheet, so that I can understand how you calculate error, etc? Thanks!

 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 Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post architect7 Multi-Way 23 27th April 2013 07:15 PM Archmage Swap Meet 16 12th February 2012 08:19 AM TurboFC3S Multi-Way 15 20th February 2009 02:43 PM kappa546 Swap Meet 15 1st September 2008 04:12 PM D.A.R.R.Y.L. Multi-Way 0 10th December 2004 07:51 AM

 New To Site? Need Help?

All times are GMT. The time now is 06:11 PM.