SPICE (Simulation Program with Integrated Circuits Emphasis) is a general purpose analog circuit simulator. It is a powerful program that is used in IC and board level design to check the integrity of circuit designs and to predict circuit behavior.

In real-world circuits, performance is affected by component value tolerances. It is difficult for designers to predict the effect of larger value tolerances. On the other hand they want to use cheaper components with large tolerances if they wish to mass produce their products. Also in radio applications, especially UHF and microwave, parasitics cannot be ignored and must be built into a generic model of the circuit being simulated. In both these cases it is usual to perform Monte Carlo simulations which are difficult or impossible to calculate by hand.

SPICE was originally developed at the Electronics Research Laboratory of the University of California, Berkeley in 1975 by Larry Nagle and Donald Pederson. Versions 1 and 2 were coded in Fortran (2G.6 in 1983 was the last) and ran on mainframe computers. Versions 3 and later are coded in C, but still use a Fortran-like syntax for circuit description. Many commercial versions of SPICE have later replaced Berkeley SPICE as the industry standard. While many are still compatible with the original Berkeley syntax, commercial vendors added proprietary extensions that limit the portability of circuit descriptions and models between different vendors. Most recent versions also include a graphical user interface for constructing circuit descriptions. For digital circuits (e.g., RAM), dedicated simulators exist that run orders of magniutude faster than the traditional Spice tools.

The original SPICE program was released under a restrictive license, which makes it difficult to improve upon the original software. A new circuit simulator, based on SPICE, called ng-SPICE (for next-generation) is licensed under the GPL. Development on the main branch of ng-SPICE stopped around 2001, but there is an active branch called tclspice. If you want a free SPICE that works on Microsoft Windows, consider LTSPICE.

First versions of Berkeley SPICE used Nodal analysis . However this meant that ideal voltage sources and inductors could not be included in the circuit. Later versions are using Modified nodal analysis , which does not have this drawback. Different algorithms are used to translate all circuit analysis problems into a single or multiple simpler problems of calculating an operating point of a linear circuit. Such problems can then be solved efficiently by solving a linear simultaneous equation. For example non-linear circuits are solved using a Newton-Raphson algorithm, which linearizes non-linear elements in a circuit. Transient analysis is performed using trapezoid or Gear integration algorithm.

Commercial versions with significant market share

• HSPICE (originally from Meta Software , now owned by Synopsys)
• PSPICE
• SmartSpice (Silvaco)
• NanoSim
• NSPICE (Apache Design Solutions )
• HSIM (NASSDA )
• B2SPICE (Beige Bag)

Also See

• IBIS Input Output Buffer Information Specification.

External links

• SPICE on gEDA HOWTO
• The Spice Page
• download TclSpice
• download ng-SPICE
• PSpice student download
• A BRIEF HISTORY OF SPICE
• LTSPICE
• Spice OPUS - Spice with integrated optimization utilities