Pspice Master Class

[12afael]

can someone give some tips to do a noise test?
what I must put on the input and output boxes on the edit simulation command window?

 

[skipwave]

[quote author="Dan Kennedy"]Don't you just love geek humor, it's so droll.[/quote]

Oh yes, there's lots of little gems on this forum. Thanks to the internet we are all so keyed in to puns. Get it..... keyed in..... internet... oh my, so lame.
Speaking of geek humor, I just found this site recently: ThinkGeek

[quote author="Dan Kennedy"]And dissipated so quickly.[/quote]

Only when properly heatsinked. Some of the components of this forum have a tendency to go into thermal breakdown. :green:

Back on topic, I've tried to play around in LTSpice, and found it useful for confirming some operating points. Although, I now better understand PRR's cocktail napkin comment, if you don't already grasp the operating method of the devices involved and whether you have them at sane operating points, the simulator is not going to be of much help. Designing a circuit without these basic assurances is like driving blindfolded using OnStar directions, the simulator won't tell you that you swerved a few meters off the road, nor will it help you pick the branches out from under your windshield wipers.

 

[rafafredd]

OK, so I´m trying to use MOSFET models on LTspice and it´s not working. I did just like I do with tubes. I´ve created a mosfet.inc file and called it using ".inc mosfet.inc" on the schematic. The .inc file contains the spice model I´ve found on the net, in two versions:

.subckt IRF820 D G S
.model mosfet NMOS( LEVEL=7 VTO=3.81 RS=0.06816 KP=2.149 RD=2.3567 TC1RD=0.0127 RG=15 IS=1e-36
+ CGDMAX=1.00E-09 CGDMIN=1.06E-11 XG2CGD=0.5 XG1CGD=0.1 CBD=6.97E-11 VTCGD=0)
.model diode D( IS=3.50e-13 RS=0.0343 TT=1.657e-06)
M1 D G S S mosfet
D1 S D Diode
Cgs G S 3.18E-10
.ends

.SUBCKT XIRF820 10 20 40 40
M1 1 2 3 3 DMOS L=1U W=1U
RD 10 1 1.42
RS 30 3 76M
RG 20 2 60
CGS 2 3 323P
EGD 12 0 2 1 1
VFB 14 0 0
FFB 2 1 VFB 1
CGD 13 14 475P
R1 13 0 1
D1 12 13 DLIM
DDG 15 14 DCGD
R2 12 15 1
D2 15 0 DLIM
DSD 3 10 DSUB
LS 30 40 7.5N
.MODEL DMOS NMOS (LEVEL=3 THETA=60M VMAX=1.04MEG ETA=2M VTO=3 KP=1.3)
.MODEL DCGD D (CJO=475P VJ=.6 M=.68)
.MODEL DSUB D (IS=10.3N N=1.5 RS=.34 BV=500 CJO=236P VJ=.8 M=.42 TT=260N)
.MODEL DLIM D (IS=100U)
.ENDS XIRF820


Then I choose NMOS from the components insert menu and rename it for IRF820, or XIRF820, but it tells me "m1: can´t find deffinition model for IRF820", just like there was no info on this model subckt on the mosfet.inc file.

The strange thing is that I do it just like that for tubes and it works great. I´ve created my own tubes.inc file and I call it anytime from my spice schems, using the preset triode or tetrode component from the insert component menu. Why does it works for tubes and not for mosfet? Did I do anything different with the tube models before that I just can´t recall?

 

[rafafredd]

BUMP, could anyone just have a look at this and help me there? Rowan? You are the LTC master... come on.

 

[analag]

[quote author="rafafredd"]BUMP, could anyone just have a look at this and help me there? Rowan? You are the LTC master... come on.[/quote]

It's much easier to implement than than. Send me your email address again and I'll walk you through. I have all the IRF models working in my sim.

analag

 

[12afael]

any chance that you share your library???

 

[analag]

What set of models do you need Mr. Engineer?

analag

 

[12afael]

tubes would be interesting, more models I have more happy I am :twisted:

I already have some tube models 12a*7 and some power pentodes but I don`t have anything usable for a vary mu (except 12au7 for PRR vary mu)

 

[rafafredd]

I would love more mosfet models, IRF, IRFP, BUZ, DN, etc...

Also, fets would be nice to have, like 2SK and 2SJ stuff, etc...

 

[analag]

Adding models to LTSpice:

Go to programs, click on LTC, then SWCIII, then lib which brings you to CMP, open that up. In there you will see folders for BJT, MOS, etc.

Example: Copy these LinearSystems JFet models directly into the Fet folder, close the program then restart and you shold be ready to go. This process applies to BJT's, MosFet's, Jfet's but not IC's.

.MODEL LSK170A NJF
+ BETA = 0.0378643 VTO = -0.4025156 LAMBDA = 4.783719E-3
+ IS = 3.55773E-14 N = 1
+ RD = 10.6565 RS = 6.8790487
+ CGD = 3.99E-11 CGS = 4.06518E-11
+ PB = 0.981382 MJ = 0.794653 FC = 0.5
+ KF = 0 AF = 1
*
.MODEL LSK170B NJF
+ BETA = 0.0350699 VTO = -0.5375582 LAMBDA = 4.951E-3
+ IS = 2.76212E-14 N = 1
+ RD = 7.82168 RS = 6.9525888
+ CGD = 4.36E-11 CGS = 4.36E-11
+ PB = 1.2 MJ = 0.8892205 FC = 0.5
+ KF = 0 AF = 1
*
.MODEL LSK170C NJF
+ BETA = 0.0278541 VTO = -0.800434 LAMBDA = 0.0122435
+ IS = 2.45217E-14 N = 1
+ RD = 12 RS = 5.8 CGD = 4.22E-11
+ CGS = 4.23E-11 PB = 0.9265487 MJ = 0.6098477
+ FC = 0.5 KF = 0 AF = 1

Hope that helps.

Next time we will get into tube models and how to tweak it to get useful simulations from them.

 

[rafafredd]

[quote author="analag"]Hope that helps.
[/quote]

Yes, helps greatly, but it sure doesn´t work for these models below as is, does it?

.subckt IRF820 D G S
.model mosfet NMOS( LEVEL=7 VTO=3.81 RS=0.06816 KP=2.149 RD=2.3567 TC1RD=0.0127 RG=15 IS=1e-36
+ CGDMAX=1.00E-09 CGDMIN=1.06E-11 XG2CGD=0.5 XG1CGD=0.1 CBD=6.97E-11 VTCGD=0)
.model diode D( IS=3.50e-13 RS=0.0343 TT=1.657e-06)
M1 D G S S mosfet
D1 S D Diode
Cgs G S 3.18E-10
.ends

.SUBCKT XIRF820 10 20 40 40
M1 1 2 3 3 DMOS L=1U W=1U
RD 10 1 1.42
RS 30 3 76M
RG 20 2 60
CGS 2 3 323P
EGD 12 0 2 1 1
VFB 14 0 0
FFB 2 1 VFB 1
CGD 13 14 475P
R1 13 0 1
D1 12 13 DLIM
DDG 15 14 DCGD
R2 12 15 1
D2 15 0 DLIM
DSD 3 10 DSUB
LS 30 40 7.5N
.MODEL DMOS NMOS (LEVEL=3 THETA=60M VMAX=1.04MEG ETA=2M VTO=3 KP=1.3)
.MODEL DCGD D (CJO=475P VJ=.6 M=.68)
.MODEL DSUB D (IS=10.3N N=1.5 RS=.34 BV=500 CJO=236P VJ=.8 M=.42 TT=260N)
.MODEL DLIM D (IS=100U)
.ENDS XIRF820

I would have to convert the syntaxe, no? (And there lies the problem)...

 

[rafafredd]

Thanks Rowan. I got your email!

 

[12afael]

for models the complete directive must be on one line or use + on the next line.

for subckts I`m not sure.

 

[analag]

[quote author="rafafredd"]Thanks Rowan. I got your email![/quote]

I'll send you some of the other stuff if you need it.

 

[aletheian-alex]

[quote author="tommypiper"]Is there one that runs on a Mac? LT looks to be Microsoft only...[/quote]

I bet you thought nobody saw that post.

Are you on an Intel Mac or PPC? I recommend installing DARWNE.

LTSpice runs just fine in the DARWINE environment on a mac. I run a lot of things in WINE and what I can't, I run on a virtualized winXP. I run an Intel Mac, and I use Parallels to open an XP window off my Boot Camp partition. Back in my G4 and G3 days, Virtual PC and Qemu with some stripped down windows version worked just fine to just run DOS helper proggies and circuit simulators. I use LTsice, and Circuitmaker daily, as well as TubeCAD, Audiotester and a few others... there is not much else on the partition.

As far as Mac-specific proggies, I used to use the Mac port of Berkley 3f4 spice ( http://www.macspice.com/ ), which is still an active project, but it is a line-code editor with o graphical interface. I tinkeres with MI-Sugar for a while, which was a generic frontend for 3f4, as well as the open-source NG-spice (i have NO idea if that is around anymore) but I just checked and the author dropped the project.

There are a million apps that you can run if you have the X11 subsystem set up properly... but I think that all the newer versions of OSX are good to go right out of the box

check out this post... a bit old... but a few links that yu can chase around.

http://macslash.org/article.pl?sid=02/12/10/2038202
[/url]

 

[rafafredd]

I'll send you some of the other stuff if you need it.

WOW, thanks for the offer. That would be mostly nice!

 

[12afael]

bcarso post this page on other topic , it have some tips on ltspice, tube models, etc.

http://digilander.libero.it/paeng/cornice.htm

I know this is not a spice meta but if I don´t put it here... I will lost the link

 

[blandman74]

LTSpice question ....


Is there a way to have LTSpice do a sweep of audio frequencies across an input, and produce an analysis of the gain/loss at an output? (I think this is called a spectral analysis, or whatever.)

I am interested in learning more about filters, and it would really help to visualize the impact of different values, topologies, etc.

 

[analag]

Yes, it's very easy to do....and the results are real world accurate.

analag

 

[12afael]

simulate/edit stimulus/AC analysis that will show you the spectral and phase graph.