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Spice of life

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Optikon

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Over the past several months I have been "evaluating" various Spice-based circuit simulators. Much to my amazement, these days there are plenty of companies offering spice solutions whether it be rolled up in their EDA software or stand alone.

I am after a spice solution that meets:

1) Easy new model creation / Library management
2) Full gamut of sim types. Monte carlo, noise etc...
3) Don't care if it is true mixed mode (analog + digital)
4) NOT a student version of anything that is node crippled or similar.
5) can import most popular formats.
6) NOT bundled with software that is thousands of USD. EDA type.

I have checked out:

* ICAP/4
* Cadence bundled
* CircuitMaker 2000 bundled
* Protel 2004 bundled
* Superspice
* Visual Spice
* Orcad Pspice

Generally, all of these are very good with drawbacks that are easily worked around. In particular, I am very impressed with visual spice but the interfaces are almost too much to handle (too much information & settings which is a love/hate relationship) but the advanced version sits in a nice couple hundred USD range for standalone version.

While creating new models might be easy, I am particularly impressed with versions that come with thousands of vendor models already built in. This saves alot of time and effort.

I have not tried Multi-sim's bunded version but like I said, I am looking to spend less than $1000 USD.

Any others that you have tried that have a high performance/price ratio??
 

Optikon

New Member
Ron H said:
Check out Linear Technology's LTspice/SwitcherCAD III. Totally free, uncastrated. You need to have some familiarity with Spice to get started.
I forgot to mention I have tried this one. It is a great simulator for the cost! :D

but..

It is not as versatile as what I am used to and analysis types are limited. If all you want to do is simulate transient response of a switching design made with linear tech parts then life is easy! It still has lots of bugs too. I had issues with multiple coupled inductors with different coupling coeff's when trying to model a transformer. But it is worthy of a home in the start menu nonetheless.

After repeated discussions with linear tech guys, they still churn out op amp macro models that have an internal node 0 for intermediate stages which prevents me from floating the supplies of opamps like I do occasionally in real world designs. So I've been a little turned off by them. But I still use em, they have some real genious designers. SWCAD has improved greatly over the years.

I guess I am trying to find the one-stop shop spice that will meet all my needs and this might be a just a dream..

What do you use?
 

samcheetah

New Member
ive only used Multisim but its really wayyyyy too expensive. i just use the limited demo version :lol: for most of the cases it serves my needs. but i really do get frustrated by the inability to save my schematics. i have heard about UltiBoard and UltiRoute which work with Multisim but i havent used them.

actually Optikon i cant suggest u any simulator because i dont have the experience with simulators that you have. i want to ask u something. in about every text book there are spice models of circuits written in plain text. ive read a couple of articles about spice and in most of them ive read the spice is better than the breed of WYSIWYG simulation software because of (i) low consumption of resources and (ii) greater options for analysis. but these days the processing power and the memory is not much of an issue. and simulators like multism provide a multitude of analysis tools. so is there any need of knowing spice?????? why build up opamp models when they are already built for you.

i think working with multisim is more "natural" in the sense that you work in multisim like you are working on a breadboard with real components. i think that speeds up the learning process and u dont need to learn spice. what do u guys have to say about this.
 

Optikon

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samcheetah said:
ive only used Multisim but its really wayyyyy too expensive. i just use the limited demo version :lol: for most of the cases it serves my needs. but i really do get frustrated by the inability to save my schematics. i have heard about UltiBoard and UltiRoute which work with Multisim but i havent used them.

actually Optikon i cant suggest u any simulator because i dont have the experience with simulators that you have. i want to ask u something. in about every text book there are spice models of circuits written in plain text. ive read a couple of articles about spice and in most of them ive read the spice is better than the breed of WYSIWYG simulation software because of (i) low consumption of resources and (ii) greater options for analysis. but these days the processing power and the memory is not much of an issue. and simulators like multism provide a multitude of analysis tools. so is there any need of knowing spice?????? why build up opamp models when they are already built for you.

i think working with multisim is more "natural" in the sense that you work in multisim like you are working on a breadboard with real components. i think that speeds up the learning process and u dont need to learn spice. what do u guys have to say about this.

Samcheetah,

For most general purpose work with simulators, there is not much need for actually knowing spice these days. I believe back when it was new, software did not exist that would interface nice fancy GUI's and make life easy for the user. So the old-timers had to know spice format & model writing. There are several reasons why one might be interested in building an op amp model.

1) The opamp you want to simulate doesnt exist in model form and the vendor you buy it from cannot/will not create a spice model.

2) The opamp you want to simulate does exist but the characteristics you are interested in model are done poorly or not at all. For example, multi-pole rolloffs. Sometimes (albeit rare) the single pole model doesnt apply or can fool you.

Generally, I will try and use a model that exists or one that is close enough to give me an answer that will resemble my circuit (might not even be the same part number). If I can convince my self that the modelling is good, I will go for it, if I have doubts I will go deeper into the model to find out (hopefully!)

So in summary, you don't need to learn spice if the software guys did an excellent job. With that said, the more you work with electronics and modelling for simulation, the more you will discover its limitations and occasionally have to go into the spice / model aspect of it. Not to mention, having a good working knowledge of how spice works is valuable for those (seemingly more frequent) times when spice won't converge on a solution!
 

samcheetah

New Member
thanx Optikon 8)

i do acknowledge the fact that sometimes u need to simulate a circuit that uses an opamp thats not available in the parts bin. but most of the times i just use a 741 whenever i need to use an opamp somewhere. i know that by doing this i limit the capabilities of my circuit and i dont get the results that i expect. but this happens very rarely. anyway ill try to manage some time and learn spice????

thanx again
 

pspicebrasil

New Member
PSPICE SIMULATION

:D HELLO,MY EXPERIENCE WITH SIMULATOR CIRCUITS,IS VERY INTERESTING PSPICE MICROSIM VERSION 8,ORCAD 9.1 AND ORCAD 10,STUDENT VERSION,BUT THE BEST POWER SIMULATION IS PSIM6,MY WEBSITE IS:
TITLE:pSPICE POWER ELECTRONICS
URL:http://caveromiranda.50megs.com/links.html
FINE THANKS,SAO PAULO BRASIL.
 
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