Spice is a powerful tool for circuit analysis. But it often surprises users with
. holes in its abilities and strange definitions
. lack of industry-wide standards
. the need for the user to model the physics of their circuit, not just draw the schematic

I hope this blog will educate users and promote discussion in these areas.

Sunday, May 26, 2013


Each post is on a separate page - the list is over here   =====>

I have been both a Spice user and a developer of a Spice program for many years. In doing this, I discovered some important Spice topics that don't seem to have a home anywhere. I'll try to address some of these here. And add more from time to time.

"How to Think Like Spice" talks about the big-picture mindset I use to work effectively with Spice. A good place to start.

If you have a topic suggestion, comment here or send me an email (spam disguised address: blogspot [at] 5spice.com). Keep in mind that simulating integrated circuit designs is a different world from my focus.

Spice Program Developer topics   (2018)
Berkeley Spice3 code has conceptual flaws and limitations plus many bugs. After years of hoarding ideas, I have added a Programmer's topic list with some of the things I have discovered/modified.
If you have a tested contribution to share, please contact me. Let's stay focused on the bigger issues.

To get the best results using circuit simulation, it is important to remember to use the tools you have. Computer simulation is a software tool that produces exact outputs based on exact inputs (well, most of the time). It can be very useful in circuit design. Circuit design is a creative and analytical process that uses the computer between your ears. If this second computer is not engaged, the results of the first are likely to be worthless.

Some posts talk about adding a specialized Spice element, such as a NodeSet, as a symbol to the schematic. This reflects usage in 5Spice. Your Spice program may add specialized Spice elements without using schematic symbols.

5Spice tutorials are now on YouTube.



  1. Does 5SPICE afford Analog Behavior Modelling?

    1. 5Spice has the NonLinear Source (the Fxy schematic symbol) that allows the user to enter an equation to control its output.

      The equation can use circuit input voltages wired to the Fxy symbol. It can use arithmetic operators, math functions, IF-THEN-ELSE logic, plus a few specialized functions.

      There is a separate schematic symbol for a piece-wise linear lookup table.

      5Spice works with Spice3 and PSpice behavioral modeling in subcircuit files.