accuracy of LTspice simulator ?

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MohEllayali

Joined: 17 Apr 2009
Posts: 20
Location: El-Harrach , Algiers

05 Nov 2009 12:05 accuracy of LTspice simulator ?

Hello everybody

In the lab I am working , they use LT spice as simulator , so I was wondering if this simulator is accurate enough
So if somebody experienced this software it would be nice if he share his impressions about it

Thanks in advance

drabos

Joined: 03 Jan 2006
Posts: 445
Helped: 30

05 Nov 2009 12:44 accuracy of LTspice simulator ?

Linear Technology does not just provide this simulation tool for everyone, but use it also for their designs, I guess that is enough as an answer Wink

This tool has a quite good reputation, especially for SMPS design.

Actually it would be quite interesting what are the exact differences between the internal LT LTSpice and the LTSpice, what everyone knows. I assume there are some...

LvW

Joined: 07 May 2008
Posts: 1466
Helped: 242
Location: Germany

05 Nov 2009 12:51 Re: accuracy of LTspice simulator ?

MohEllayali wrote:

Certainly, all simulators based on the SPICE code are "accurate enough".
But you should not forget that every calculation (by hand or by computer) can be only as exact as the input data are. In case of a simulation program the results agree with the real world (within certain limits) if the models of the various components and subcircuits (opamps) are "accurate enough" - what ever this means for a specific application.
But, more than that, one should know about the specific properties of the various analyses. For example: The AC analysis by nature does not consider any supply voltage limits and no non-linearities. This leads, for example, to the result, that an opamp with positive feedback finds a stable operating point and amplifies!
But that is no error. The result is correct and you can verify it by hand calculations (neglecting switch-on effects and power supply variations - as done during ac analysis).

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dick_freebird

Joined: 04 Mar 2008
Posts: 312
Helped: 45
Location: USA

05 Nov 2009 15:59 accuracy of LTspice simulator ?

The core is SPICE based (long ago) with LT enhancements
and extensions. For the supported device models I expect
its accuracy is the same, and controlled by the same
sort of tolerance variables, as other SPICEs. These settings
are the first thing to look at, along with solution method,
if you are looking for accuracy. For example, a TRAP
method when you are looking for noise qualities in a transient
simulation, is a bad idea because you tend to get a sawtooth
of TRTOL amplitude even on quiet nodes.

What to beware, is the accuracy of their models for complex
parts. These are macromodeled and LT warns you about
the possibility of detail-inaccurate results although they
seem to have done a reasonable job from the few ones
I have messed with.

snafflekid

Joined: 09 May 2007
Posts: 120
Helped: 16
Location: USA

06 Nov 2009 0:54 Re: accuracy of LTspice simulator ?

I have not done a side by side comparison of LTspice to other simulators. But I can actually understand and adjust LTspice simulator unlike other simulators with a thousand useless buttons (cadence, mentor graphics I'm looking at you)

haker_fox

Joined: 24 Jun 2009
Posts: 51
Helped: 4
Location: Russia, Irkutsk

06 Nov 2009 1:34 Re: accuracy of LTspice simulator ?

MohEllayali wrote:

Hello everybody

In the lab I am working , they use LT spice as simulator , so I was wondering if this simulator is accurate enough

This simulator uses PSPICE core inside. Consequently you may suppose that much of accuracy depend on correctness of used modes. I think so. However I prefer using original PSPICE built-in OrCAD, for example.
In general I have been using everywhere widely known Micro-CAP until now. But now I needed some models like mc34063, ir2104 which is written on spice. Therefore it's better and easier take PSPICE simulator and use them without any troubles.