Simulating analog circuits

Hi there - recently I've been doing more and more analog circuit design. I've been using LTspice for this, but I'm wondering if there is anything better? I worry that since LTspice is really designed (to the best of my understanding, at least) to simulate switching supplies, it might not be a good fit for complicated analog circuitry.

Are there better things out there? At work we use Altium Designer, and it seems like there is a simulation package associated with that, though I have never attempted to use it. I've seen various other spice variants as well.

What do you think?



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LTSpice uses the same Spice simulator that just about everything else does, Berkeley SPICE 3. Interfaces into spice vary, Altium uses spice

3 also.

The only basic difference until you get into hspice or other so- expensive-it's-scary products is the interface and the library that comes with the product. Some simulators include support for non-linear elements like transmission lines and arbitrary mathematically defined blocks. Others integrate XSpice from Georgia Tech, this gives you digital/mixed signal simulation capability. I believe spice 3 doesn't include real magnetic elements like non-ideal inductors/transformers.

Altium includes a mixed signal simulator that integrates with their HDL simulator, and also includes (I believe) arbitrary s-domain blocks and transmission lines as the major features above LTspice. LT spice also does not (as far as I know) things like sensitivity analysis and monte-carlo runs, which Altium has. These can all be done within the spice 3/xspice framework, but some vendors don't add these features.


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If you can run Linux programs, you might like to look at gnucap

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which isn't based on Berkely Spice, though it will run models developed for Berkely spice and its numerous instantiations (of which LTSpice is one of the cheapest - since it is free, and relatively easy to learn to use - and not far off being one of the best).

-- Bill Sloman, Nijmegen

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What's non-linear about a transmission line?

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Hal Murray

"Michael" schrieb im Newsbeitrag news:

Hello Michael,

What are you missing in LTspice? It's at least as good as other SPICEs for pure analog circuits.

It will depend on your application.

Other simulators often have a large but not up to date library of opamps. It's easy to use any third party opamp models in LTspce.

Do you need models of complex coupled and lossy transmission lines like available in HSPICE, ELDO and ADS? Be warned, only a few of us could convince our employers to buy these very expensive simulators.

Do you need support of IBIS models like in HSPICE, ELDO and ADS or semi-automatic with MCAP, ICAP? This is indeed an argument to buy one of these simulators.

If you already have a license of any SPICE simulator and it's easy to use, it's worth to look at it.

Are you looking for a widely used simulator to discuss circuits? LTspice is the only free of charge and unlimited SPICE simulator with integrated schematic entry and waveform viewer.

The support in user groups is inversely proportional to the price of a tool. That's my experience.

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Best regards, Helmut

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Helmut Sennewald

If you want to compare LTspice against mid-priced Spice programs like PSpice, the only real difference I find is the graphing utility. Otherwise, LTspice works quiet well. I've switched over from PSpice to LTspice for most of my simulation work where I don't need the graphing features of PSpice. I've ran parts of an ASIC design that a contractor was doing for us thru LTspice to see how it compared with PSpice. Worked just fine. Don't be fooled by the price. It's a wonderful simulator, even for if you had to pay for it.


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Yep. Pass it on to Mikey... match Probe's capabilities and you've got a convert ;-)

...Jim Thompson

|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Jim Thompson

Typing with my eyes closed, I meant to say non-ideal transmission lines.

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Funny; making an *analog* of an analog circuit...

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Robert Baer

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