Yesterday I went to a seminar sponsored by NuHorizons the purpose of which was to present Linear Technology's free LTspice program. Mike Engelhardt whose job at Linear Technology is to continually develop the simulator gave the seminar. Who is a better person to ask a question of pertaining to a program than the author himself?

The seminars are taking place all over the world starting in September and finishing up in November. If you can find the time, and I recommend that you seriously try to, you can register at NuHorizons. On the unfortunate chance that you can't make it to one of the seminars you can download the complete presentation and all its examples here. There are also several Yahoo groups dedicated to LTspice users: LTspice, LTspiceDocs and LTspiceFiles.

Mike has been developing simulators for more than thirty years and has been with Linear Technology since LTspice's inception. He shares a common past with the original Berkley SPICE program, formerly named CANCER, in that he was a graduate student at Berkley some many years ago. He is extremely well versed in the subjects of analog circuits, simulation and high performance multi-threaded software development. All this in spite of the fact that he was a physics major. Many engineers are humbled for lack of an analog or software background in comparison.

LTspice is completely free to download and use with someone downloading the program every four minutes on average. Over a wide sample of circuits LTspice seriously outperforms hspice and PSpice (see slide 21 of the presentation which is from many years ago when the program wasn't multi-threaded, so watch out your results will be faster still), both of which are applications that you have to pay good money for that if you get results they might take longer. LTspice, besides being fast, has many enhancements that make it useable for doing mixed mode (with digital circuits) simulations that allow it to perform switch mode power supply simulations, which is the reason LTC provides it to its customers and everyone else. Of all the Spice simulators available in the world, LTspice claims to be the fastest, most accurate and most robust (solves a circuit instead of crashing or giving up). Being multi-treaded, LTspice truly takes advantage of the Intel Core i7 CPUs and takes full advantage of those mice with the scroll wheel that can be pushed side to side to scroll waveforms horizontally, so tell your boss and get a shinny new computer. Internally LTC uses this very same simulator for circuit development so why not you too?

With the presentation download you will benefit greatly but actually attending the seminar you will be blessed with many tidbits of knowledge not contained therein as well as some humorous tales. The program contains the largest collection of (accurate) models that can be extended by the user. There is an alternate solver that can be selected that is 1000x more accurate but 2x slower and when you might want to enable it. To educate yourself, slide 6 shows a whole directory of circuits that include the first opamp from George A. Philbrick Researches, Inc. but the story of why nobody could reverse engineer the $600 component is for attendee's only.

To help you get up to speed quickly, you may want to download this application note that will provide step-by-step instructions on downloading, installing and using LTspice.