On Sun, 29 Jun 2014 14:20:22 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Sun, 29 Jun 2014 14:16:29 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Sun, 29 Jun 2014 13:19:31 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>>On Sun, 29 Jun 2014 13:08:03 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Sun, 29 Jun 2014 11:48:52 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>>On Sun, 29 Jun 2014 11:24:05 -0700, John Larkin >>>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>>> >>>>>>On Sun, 29 Jun 2014 09:58:04 -0700, Jim Thompson >>>>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>>> >>>>>>>On Sun, 29 Jun 2014 07:29:40 -0700, John Larkin >>>>>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> >>>>>>>>On Sun, 29 Jun 2014 01:15:08 -0700 (PDT), whit3rd <whit3rd@gmail.com> wrote: >>>>>>>> >>>>>>>>>On Friday, June 27, 2014 4:20:18 PM UTC-7, John Larkin wrote: >>>>>>>>>> What's an easy way to plot the C-V curve of a back-biased diode? >>>>>>>>> >>>>>>>>>Easy, is to buy the source/meter Keithley solution. They'd love >>>>>>>>>to explain it all to you... >>>>>>>>><http://www.keithley.com/promo/lp/semiconductor> >>>>>>>> >>>>>>>>I bought an expensive Keithley source-meter. Crap. Sent it back. >>>>>>>> >>>>>>>>But I meant in LT Spice, which is why I titled the post "LT Spice..." >>>>>>>> >>>>>>>>I can read the C-V curve off the data sheet. What I want to do is make sure (or >>>>>>>>force) my Spice sim to behave like the actual diode, so I want to do a >>>>>>>>simulation of the diode c-v curve, to make sure I have everything right. >>>>>>> >>>>>>>I don't know how to post-process data in LTspice, but here's how I do >>>>>>>it in PSpice... >>>>>>> >>>>>>><http://www.analog-innovations.com/SED/C-V_Plot%20-%20PSpice%20AD.png> >>>>>>> >>>>>>>An alternative is to do it like the Keithley does, superimpose a small >>>>>>>sinusoidal signal on the DC, and measure the co-sinusoidal current. >>>>>>> >>>>>>> ...Jim Thompson >>>>>> >>>>>>The voltage ramp thing that I did seems OK. >>>>>> >>>>>>It does report the initial capacitance of a 1N914 as 4 pF, which is high, but >>>>>>that's the value in the LT Spice model. >>>>> >>>>>The PSpice model has the same CJ0. >>>>> >>>>> ...Jim Thompson >>>> >>>>Various data sheets have typs from 4 to 0.85. Not the thing you'd want to use as >>>>a varicap. >>>> >>>>I do need a "power varicap" for a weird thing I'm considering. I figured I'd >>>>fudge up some standard LT library parts, series and parallel or whatever, to see >>>>if my circuit might work. If it does, then I can try to find real diodes with >>>>the required CV curves. >>> >>>What's your maximum voltage? You might want to try some zeners. >>> >>> ...Jim Thompson >> >>Oh, 4KV or so. > >Oooooh! And probably need 10:1 capacitance also ?:-) > > ...Jim ThompsonSure, that sounds good. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
LT Spice diode C-V graph
Started by ●June 27, 2014
Reply by ●June 29, 20142014-06-29
Reply by ●June 29, 20142014-06-29
John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>>>>What's your maximum voltage? You might want to try some zeners.>>>> ...Jim Thompson>>>Oh, 4KV or so.>>Oooooh! And probably need 10:1 capacitance also ?:-)>> ...Jim Thompson> Sure, that sounds good.Get a nice Y5V. Capacitance ratio as high as 14:1. Voltage rating up to 15kv. http://www.maximintegrated.com/en/app-notes/index.mvp/id/5527 Probably the most unstable capacitor available. High drift with temperature and time. Microphonic. See Page 20, 22 of http://www.darfon.com/tw/Folder/MLCC/MLCC/Y5V%20sreies.pdf
Reply by ●June 29, 20142014-06-29
On Sun, 29 Jun 2014 23:24:51 GMT, Steve Wilson <none@nospam.com> wrote:>John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>>>>What's your maximum voltage? You might want to try some zeners. > >>>>> ...Jim Thompson > >>>>Oh, 4KV or so. > >>>Oooooh! And probably need 10:1 capacitance also ?:-) > >>> ...Jim Thompson > >> Sure, that sounds good. > >Get a nice Y5V. Capacitance ratio as high as 14:1. Voltage rating up to >15kv. > >http://www.maximintegrated.com/en/app-notes/index.mvp/id/5527 > >Probably the most unstable capacitor available. High drift with >temperature and time. Microphonic.Other than being unstable with voltage, temperature, vibration, and time, they're perfect. ;-)>See Page 20, 22 of > >http://www.darfon.com/tw/Folder/MLCC/MLCC/Y5V%20sreies.pdf
Reply by ●June 29, 20142014-06-29
On Sunday, June 29, 2014 2:16:29 PM UTC-7, John Larkin wrote:> On Sun, 29 Jun 2014 13:19:31 -0700, Jim Thompson> >>I do need a "power varicap" for a weird thing I'm considering. I figured I'd > >>fudge up some standard LT library parts, series and parallel or whatever, to see > >>if my circuit might work. If it does, then I can try to find real diodes with > >>the required CV curves.> >What's your maximum voltage? You might want to try some zeners.> Oh, 4KV or so.That's easy. Start with an electrostatic voltmeter. Put extra capacitor vanes onto the shaft instead of a pointer. It's a hard thing to arrange in solid state, though.
Reply by ●June 29, 20142014-06-29
On Sun, 29 Jun 2014 23:24:51 GMT, Steve Wilson <none@nospam.com> wrote:>John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>>>>What's your maximum voltage? You might want to try some zeners. > >>>>> ...Jim Thompson > >>>>Oh, 4KV or so. > >>>Oooooh! And probably need 10:1 capacitance also ?:-) > >>> ...Jim Thompson > >> Sure, that sounds good. > >Get a nice Y5V. Capacitance ratio as high as 14:1. Voltage rating up to >15kv. > >http://www.maximintegrated.com/en/app-notes/index.mvp/id/5527 > >Probably the most unstable capacitor available. High drift with >temperature and time. Microphonic.Yum, just what I want! -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
Reply by ●June 29, 20142014-06-29
On Sun, 29 Jun 2014 14:19:22 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:>>> ..snip... > > PSpice supports the Berkeley (dot)PRINT statement, so I can generate > columnized data simply by adding, in LTspice lingo, a "Spice > directive" .PRINT V(N_27) I(VDC:+) etc. > > It's really odd that LTspice doesn't support that :-( > > ...Jim ThompsonSurprised me too, but not sure where LTspice would put the results. From memory PSpice .PRINT statement puts the column as text into the end of all the quiescent data. so have to go through and separate it there. At least LTspice let's you save the list AFTER the analysis and puts only the requested data into a file. Seems like more a matter of preference.
Reply by ●June 30, 20142014-06-30
On Sun, 29 Jun 2014 14:20:22 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:>>>>>> ...something about CJ0 being 4pF >>>>> >>>>> The PSpice model has the same CJ0. >>>>> >>>>> ...Jim Thompsonfrom my old PSpice .LIB not later than 92, possibly before .MODEL D1N914 D(IS=0.1P RS=16 CJO=2P TT=12N BV=100 IBV=0.1P) .MODEL D1N914A D(IS=0.1P RS=4 CJO=2P TT=12N BV=100 IBV=0.1P) isn't that 'initial' CJO like with zero volts across the junction? arrrggg! can't remember anything about diode models tonight.
Reply by ●June 30, 20142014-06-30
On Sun, 29 Jun 2014 14:21:11 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:> On Sun, 29 Jun 2014 14:15:30 -0700 (PDT), Lasse Langwadt Christensen > <langwadt@fonz.dk> wrote: > >> ...snip.... >> just install something like octave or scilab, simple scripting of every >> file handling, plotting and curve fitting function you can imagine >> >> >> -Lasse > > Which is better? > > ...Jim Thompsonuh, for all those mathematical manipulations, I use octave 2.1.50a version ...for a reason and write all the scripts using the Scilab Editor, called Sc1, also use if for C/C++ and other stuff because it has auto indent AND color etc. One of the few editors that easily opens 100MB files also doesn't get upset if you accidently open an exe file, or such.
Reply by ●June 30, 20142014-06-30
On Sun, 29 Jun 2014 15:05:22 -0700, Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>> ...snip... > on windows probably scilab > > Octave is much more Matlab compatible but to get a gui you need to get > version 3.8+ but that's "experimental" for windows > http://mxeoctave.osuv.de/ > > Matlab is the Rolls-Royce, but it comes at a Rolls-Royce price > > -Lasseoctave is purposely a clone of Matlab, however I prefer the 'command line' approach of octave over a stupid gui.
Reply by ●June 30, 20142014-06-30
On Sun, 29 Jun 2014 21:21:20 -0700, RobertMacy <robert.a.macy@gmail.com> wrote:>On Sun, 29 Jun 2014 14:20:22 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote: > >>>>>>> ...something about CJ0 being 4pF >>>>>> >>>>>> The PSpice model has the same CJ0. >>>>>> >>>>>> ...Jim Thompson > > from my old PSpice .LIB not later than 92, possibly before >.MODEL D1N914 D(IS=0.1P RS=16 CJO=2P TT=12N BV=100 IBV=0.1P) >.MODEL D1N914A D(IS=0.1P RS=4 CJO=2P TT=12N BV=100 IBV=0.1P) > >isn't that 'initial' CJO like with zero volts across the junction? >arrrggg! can't remember anything about diode models tonight.Probably selected grades, as in... *$ .model D1N914 D(Is=168.1E-21 N=1 Rs=.1 Ikf=0 Xti=3 Eg=1.11 Cjo=4p *$ .model D1N914a D(Is=100f N=1 Rs=16 Ikf=0 Xti=3 Eg=1.11 Cjo=2p M=.3333 *$ ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, 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 love to cook with wine. Sometimes I even put it in the food.
