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Does anyone know of a freeware SPICE / circuit simulator? SPICE (Simulation Program with Integrated Circuit Emphasis)is a general-purpose, open source analog electronic circuit simulator. It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior. Wikipedia

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As long as you're doing the whole 'ask common questions and answer them' thing, might be good to put some info in here about what a SPICE simulator exactly is (even if it's just a cut and paste from wikipedia) – davr Dec 22 '09 at 2:15
Oh well, I confused circuit / board-level simulation with SPICE simulation. – Edward Dec 22 '09 at 3:11
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Are you asking for freeware or open source? – Johan Jul 10 '10 at 9:24
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I think the answer to the original question is "yes". – XTL Jul 12 '10 at 8:08

7 Answers

up vote 26 down vote
  • ngSpice is available for gEDA.
  • gnuCAP is also available for gEDA.
  • LTSpice is free from Linear Technology.

I thought that one of the other analog chip makers had a spice too but I can't remember who :(

I have been to a few talks on simulation given by physicists and EEs who have done chip design. Each of the talks seems to end like this ---

  • Except for simple circuits you will spend most of your time getting models and determining where the models need to be modified for your application.
  • Unless you are doing work for an IC manufacturer the manufacturer will not give you detailed models.
  • You will not be able to avoid a prototype.
  • You should only simulate subsections of your design. Simulating the entire design is not usually practical.

Also most of the free simulators are not distributed with models. Re-distribution of the models is usually a copyright violation. LTspice is distributed with models of the Linear Tech parts. I am not sure the quality of the models. Most manufacturers do not want to reveal too many details about their process.

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+1 for LTSpice. The most maintained one from my point of view – Rocket Surgeon Jun 22 '12 at 23:44
up vote 11 down vote

A free version of TINA, which includes Spice, is available from TI.

I use SIMetrix Spice, it is an option with the Pulsonix PCB software I use. It's a very good implementation, and a free demo version is available that is suitable for small circuits:

SIMetrix

This is a very nice SPICE that I investigated some years ago. It can be used with Eagle schematics.

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+1 for TINA-TI. – endolith Jan 25 '10 at 21:00
up vote 10 down vote

my favorite spice engine is the one made by linear technology. I saw ngSpice mentioned above but there is no good port to windows. Its cool if you have the linux box. But I find it has some compatibility issues and library import issues.

http://www.linear.com/designtools/ That is where LTspice is, they have filter design tools there too.

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I have used LTspice for years and the Yahoo group is very active with help, support, demo files and expanding libary of models. tech.groups.yahoo.com/group/LTspice – Alan Tester Jun 23 '10 at 7:40
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LTspice is a windows app, but is designed to also run under WINE, so you can use it on Mac/Linux with an appropriate wine-based interface layer. – Windell Oskay Aug 16 '10 at 23:02
ngspice is based on Spice 3f5 while most commercial offerings used the Spice 2 code as a base. This does not mean they are worse since the Spice 3 rewrite is not all roses. Back to the point: the most important difference is the change in specification of nonlinear components (POLYNOMIAL vs. normal equation) which breaks many models and treating node names as strings (in the original Spice 2 they had to be numbers and were compared numerically 0 == 00). – jpc Apr 1 '11 at 16:28
+1: LTspice is where it's at. Free, fast, large community, runs on Linux (with Wine). – Renan Jan 12 at 0:35
up vote 9 down vote

I found an excellent online circuit simulator written in Java, and its free-and-open-source. You can play with the software by visiting the link, and wait for the applet to pop-up. (you need the Java Player)

Edit components and connections by right-clicking anywhere/on a component. You can build entire circuits using this and simulate it visually to understand how the circuit works. (voltage is shown in green/red, simply amazing) If you start with one of the gate circuit examples, (choose it from the Circuits menu), then you can click on gates or digital signals to switch them on/off, and see your circuit react.

You can setup oscilloscope views on any connection too. (see bottom of the pic)

alt text

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This is a circuit simulator, but I don't think it has anything to do with SPICE. – davr Dec 22 '09 at 2:13
@davr You are right. I took the liberty to edit the post and remove the SPICE mention so it will not confuse people. – jpc Apr 1 '11 at 16:23
It was definitely a good idea to remove the misleading reference from this answer, but the question is about SPICE - Why is an answer that doesn't even mention SPICE so highly voted? – Kevin Vermeer Apr 1 '11 at 18:37
up vote 7 down vote

There are a couple of heavy-duty packages and a lightweight program for Linux.

The serious packages are GEDA and KiCAD. They are each a collection of programs that work well together (like Orcad); they include a schematic capture, a simulator, a waveform viewer, and a PCB layout tool. They are very sufficient except my professor requires the ".out" file generated by pspice, so I still have to use that.

The lightweight program is Oregano. It's great for quick simulations. The libraries are quick and easy to use and find parts from. The schematic capture is much easier to use and prettier than the other programs. It uses either gnucap or ngspice for the simulations, so they're pretty good. One major drawback that I have found is that the waveform viewer does not provide a logarithmic view and there's no way to get data out of it.

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up vote 2 down vote

You can use Qucs.

For logics circuits, you can use this great online simulator called Logicly.

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