SPICE (Simulation Program with Integrated Circuit Emphasis) is a general-purpose
analog electronic circuitAnalogue electronics are those electronic systems with a continuously variable signal. In contrast, in digital electronics signals usually take only two different levels. The term "analogue" describes the proportional relationship between a signal and a voltage or current that representes the...
simulatorElectronic circuit simulation uses mathematical models to replicate the behavior of an actual electronic device or circuit. Simulating a circuit’s behavior before actually building it greatly improves efficiency and provides insights into the behavior of electronics circuit designs...
.
It is a powerful program that is used in
ICIn electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin substrate of semiconductor material...
and board-level design to check the integrity of
circuit designThe process of circuit design can cover systems ranging from complex electronic systems all the way down to the individual transistors within an integrated circuit...
s and to predict
circuitAn electronic circuit is a closed path or paths formed by the interconnection of electronic components through which an electric current can flow....
behavior.
Introduction
Integrated circuits, unlike board-level designs composed of discrete parts, are impossible to
breadboardA breadboard is a construction base for a one-of-a-kind electronic circuit, a prototype. In modern times the term is commonly used to refer to a particular type of breadboard, the solderless breadboard ....
before manufacture. Further, the high costs of
photolithographic masksA photomask is an opaque plate with holes or transparencies that allow light to shine through in a defined pattern. They are commonly used in photolithography.-Overview:...
and other manufacturing prerequisites make it essential to design the circuit to be as close to perfect as possible before the integrated circuit is first built. Simulating the circuit with SPICE is the industry-standard way to verify circuit operation at the transistor level before committing to manufacturing an integrated circuit.
Board-level circuit designs can often be breadboarded for testing. Even with a breadboard, some circuit properties may not be accurate compared to the final printed wiring board, such as parasitic resistances and capacitances. These parasitic components can often be estimated more accurately using SPICE simulation. Also, designers may want more information about the circuit than is available from a single mock-up. For instance, circuit performance is affected by component manufacturing tolerances. In these cases it is common to use SPICE to perform
Monte CarloMonte Carlo methods are a class of computational algorithms that rely on repeated random sampling to compute their results. Monte Carlo methods are often used when simulating physical and mathematical systems. Because of their reliance on repeated computation of random or pseudo-random numbers,...
simulations of the effect of component variations on performance, a task which is impractical using calculations by hand for a circuit of any appreciable complexity.
Circuit simulation programs, of which SPICE and derivatives are the most prominent, take a text
netlistThe word netlist can be used in several different contexts, but perhaps the most popular is in the field of electronic design. In this context, a "netlist" describes the connectivity of an electronic design....
describing the circuit elements (transistors, resistors, capacitors, etc.) and their connections, and translate
this description into equations to be solved. The general equations produced are nonlinear
differential algebraic equationIn mathematics, differential algebraic equations are a general form of differential equation, given in implicit form. They can be writtenwhere* , a vector in , are variables for which derivatives are present ,...
s which are solved using
implicit integration methodsExplicit and implicit methods are approaches used in numerical analysis for obtaining numerical solutions of time-dependent ordinary and partial differential equations, as is required in computer simulations of physical processes....
,
Newton's methodIn numerical analysis, Newton's method , named after Isaac Newton and Joseph Raphson, is perhaps the best known method for finding successively better approximations to the zeroes of a real-valued function...
and
sparse matrixIn the mathematical subfield of numerical analysis a sparse matrix is a matrix populated primarily with zeros .Conceptually, sparsity corresponds to systems which are loosely coupled. Consider a line of balls connected by springs from one to the next; this is a sparse system...
techniques.
Origins
SPICE was developed at the Electronics Research Laboratory of the
University of California, BerkeleyThe University of California, Berkeley is a public research university located in Berkeley, California, United States. The oldest of the ten major campuses affiliated with the University of California, Berkeley offers some 300 undergraduate and graduate degree programs in a wide range of disciplines...
by Laurence Nagel with direction from his research advisor, Prof.
Donald PedersonDonald O. Pederson was an American electrical engineer and one of the designers of SPICE, the canonical integrated circuit simulator.- Biography :...
. SPICE1 was largely a derivative of the CANCER program, which Nagel had worked on under Prof. Ronald Rohrer. CANCER was an acronym for "Computer Analysis of Nonlinear Circuits, Excluding Radiation," a hint to Berkeley's liberalism of 1960s: at these times many circuit simulators were developed under the
United States Department of DefenseThe United States Department of Defense is the federal department charged with coordinating and supervising all agencies and functions of the government relating directly to national security and the military...
contracts that required the capability to evaluate the radiation hardness of a circuit. When Nagel's original advisor, Prof. Rohrer, left Berkeley, Prof. Pederson became his advisor. Pederson insisted that CANCER, a proprietary program, be rewritten enough that restrictions could be removed and the program could be put in the public domain.
SPICE1 was first presented at a conference in 1973. SPICE1 was coded in
FORTRANFortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
and used
nodal analysisIn electric circuits analysis, nodal analysis, node-voltage analysis, or the branch current method is a method of determining the voltage between "nodes" in an electrical circuit in terms of the branch currents.In analyzing a circuit using Kirchoff's circuit laws, one can either do nodal analysis...
to construct the circuit equations. Nodal analysis has limitations in representing inductors, floating voltage sources and the various forms of controlled sources. SPICE1 had relatively few circuit elements available and used a fixed-timestep transient analysis. The real popularity of SPICE started with SPICE2 in 1975. SPICE2, also coded in FORTRAN, was a much-improved program with more circuit elements, variable timestep transient analysis using either trapezoidal or the Gear integration method (also known as
BDFThe backward differentiation formula is a family of implicit methods for the numerical integration of ordinary differential equations. They are linear multistep methods that, for a given function and time, approximate the derivative of that function using information from already computed times,...
), equation formulation via
modified nodal analysisIn Electrical Engineering Modified Nodal Analysis or MNA is an extension of nodal analysis which not only determines the circuit's node voltages , but also some branch currents. Modified nodal analysis was developed as a formalism to mitigate the difficulty of representing voltage-defined...
(avoiding the limitations of nodal analysis), and an innovative FORTRAN-based memory allocation system developed by another graduate student, Ellis Cohen. The last FORTRAN version of SPICE was 2G.6 in 1983. SPICE3 was developed by Thomas Quarles (with
A. Richard NewtonArthur Richard Newton was the dean of the University of California, Berkeley College of Engineering....
as advisor) in 1989. It is written in
CC is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, uses the same netlist syntax, and added
X Window SystemThe X Window System is a computer software system and network protocol that provides a graphical user interface for networked computers, and was initially developed as part of Project Athena...
plotting.
As an early
open sourceOpen source is an approach to the design, development, and distribution of software, offering practical accessibility to a software's source code. Some consider open source as one of various possible design approaches, while others consider it a critical strategic element of their operations...
program, SPICE was widely distributed and used. Its ubiquity became such that "to SPICE a circuit" remains synonymous with circuit simulation. SPICE source code was from the beginning distributed by UC Berkeley for a nominal charge (to cover the cost of magnetic tape). The license originally included distribution restrictions for countries not considered friendly to the USA, but the source code is currently covered by the BSD license.
SPICE inspired and served as a basis for many other circuit simulation programs, in academia, in industry, and in commercial products. The first commercial version of SPICE was ISPICE, an interactive version on a timeshare service,
National CSSNational CSS, Inc. was a time-sharing firm in the 1960-80s, until its acquisition by Dun & Bradstreet in 1979. NCSS was originally headquartered in Norwalk, Connecticut, but relocated to Wilton in 1978. Sales offices, data centers, and development facilities were located at various sites...
. The most prominent commercial versions of SPICE include HSPICE (originally commercialized by Shawn and Kim
Hailey of Meta Software, but now owned by
SynopsysSynopsys, Inc. is one of the largest companies in the electronic design automation industry. Synopsys' first and best-known product is Design Compiler, a logic-synthesis tool. Synopsys offers a wide range of other products used in the design of an application-specific integrated circuit...
) and
PSPICEPSpice is a SPICE analog circuit and digital logic simulation software that runs on personal computers, hence the first letter "P" in its name. It was developed by MicroSim and is used in electronic design automation. MicroSim was bought by OrCAD which was subsequently purchased by Cadence Design...
(now owned by
Cadence Design SystemsCadence Design Systems, Inc is an electronic design automation software and engineering services company, founded in 1988 by the merger of SDA Systems and ECAD, Inc. For years it had been the largest company in the EDA industry...
). The academic spinoffs of SPICE include XSPICE, developed at
Georgia TechThe Georgia Institute of Technology, commonly called Georgia Tech, Tech, and GT, is a public, coeducational research university in Atlanta, Georgia in the United States...
, which added mixed analog/digital "code models" for behavioral simulation, and Cider (previously CODECS, from UC Berkeley/Oregon State Univ.) which added
semiconductor device simulationSemiconductor device modeling creates models for the behavior of the electrical devices based on fundamental physics, such as the doping profiles of the devices. It may also include the creation of compact models , which try to capture the electrical behavior of such devices but do not generally...
. The integrated circuit industry adopted SPICE quickly, and until commercial versions became well developed many IC design houses had proprietary versions of SPICE. Today a few IC manufacturers, typically the larger companies, have groups continuing to develop SPICE-based circuit simulation programs. Among these are ADICE at
Analog DevicesAnalog Devices, Inc. , is an American multinational semiconductor company specializing in data conversion and signal conditioning technology. Analog Devices serves over 60,000 customers representing a wide variety of electronic equipment types, including industrial and medical equipment, wireless...
, LTspice at
Linear TechnologyLinear Technology Corporation , founded in 1981 by Robert Swanson and Bob Dobkin, designs, manufactures and markets a broad line of standard high performance integrated circuits...
, Mica at
Freescale SemiconductorFreescale Semiconductor, Inc. is an American semiconductor manufacturer. It was created by the divestiture of the Semiconductor Products Sector of Motorola in 2004. Freescale focuses their integrated circuit products on the automotive, embedded and communications markets...
, and TISPICE at
Texas InstrumentsTexas Instruments , widely known as TI, is an American company based in Dallas, Texas, United States, renowned for developing and commercializing semiconductor and computer technology. TI is the No. 4 manufacturer of semiconductors worldwide after Intel, Samsung and Toshiba, and is the top supplier...
. (Other companies maintain internal circuit simulators which are not directly based upon SPICE, among them PowerSpice at
IBMInternational Business Machines Corporation, abbreviated IBM, is a multinational computer technology and IT consulting corporation headquartered in Armonk, Town of North Castle, New York, United States. The company is one of the few information technology companies with a continuous history dating...
, Titan at
QimondaQimonda AG , was a memory company split out of Infineon Technologies on 1 May 2006, to form at the time the second largest DRAM company worldwide, according to the industry research firm Gartner Dataquest...
, Lynx at
Intel CorporationIntel is the world's largest semiconductor chip maker, based on revenue. The company is the inventor of the x86 series of microprocessors, the processors found in most personal computers. Intel was founded on July 18, 1968, as Integrated Electronics Corporation and based in Santa Clara,...
, and Pstar at NXP Semiconductor.)
Program features and structure
SPICE became popular because it contained the analyses and models needed to design integrated circuits of the time, and was robust enough and fast enough to be practical to use. Precursors to SPICE often had a single purpose: The BIAS program, for example, did simulation of bipolar transistor circuit operating points; the SLIC program did only small-signal analyses. SPICE combined operating point solutions, transient analysis, and various small-signal analyses with the circuit elements and device models needed to successfully simulate many circuits.
Analyses
SPICE2 included these analyses:
- AC analysis (linear
The word linear comes from the Latin word linearis, which means created by lines.In mathematics, a linear map or function f is a function which satisfies the following two properties......
small-signalSmall-signal modeling is a common analysis technique in electrical engineering which is used to approximate the behavior of nonlinear devices with linear equations...
frequency domain analysis)
- DC analysis (nonlinear quiescent point calculation)
- DC transfer curve analysis (a sequence of nonlinear operating points calculated while sweeping an input voltage or current, or a circuit parameter)
- Noise analysis (a small signal analysis done using an adjoint matrix technique which sums uncorrelated noise currents at a chosen output point)
- Transfer function
A transfer function is a mathematical representation, in terms of spatial or temporal frequency, of the relation between the input and output of a system. With optical imaging devices, for example, it is the Fourier transform of the point spread function i.e...
analysis (a small-signal input/output gain and impedance calculation)
- Transient analysis (time-domain large-signal solution of nonlinear differential algebraic equations)
Since SPICE is generally used to model nonlinear circuits, the small signal analyses are necessarily preceded by a quiescent point calculation at which the circuit is linearized. SPICE2 also contained code for other small-signal analyses:
sensitivity analysisSensitivity analysis is the study of how the variation in the output of a mathematical model can be apportioned, qualitatively or quantitatively, to different sources of variation in the input of a model ....
, pole-zero analysis, and small-signal
distortionA distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted...
analysis. Analysis at various temperatures was done by automatically updating semiconductor model parameters for temperature, allowing the circuit to be simulated at temperature extremes.
Other circuit simulators have since added many analyses beyond those in SPICE2 to address changing industry requirements. Parametric sweeps were added to analyze circuit performance with changing manufacturing tolerances or operating conditions. Loop gain and stability calculations were added for analog circuits. Harmonic balance or time-domain steady state analyses were added for RF and switched-capacitor circuit design. However, a public-domain circuit simulator containing the modern analyses and features needed to become a successor in popularity to SPICE has not yet emerged.
Device models
SPICE2 included many semiconductor device
compact modelsTransistors are simple devices with complicated behavior. In order to ensure the reliable operation of circuits employing transistors, it is necessary to scientifically model the physical phenomena observed in their operation using transistor models. There exists a variety of different models that...
: three levels of MOSFET model, a combined Ebers–Moll and
Gummel-Poon bipolar modelThe Gummel–Poon model is a model of the bipolar junction transistor. It was first described in a paper published by Hermann K. Gummel and H.C. Poon at Bell Labs in 1970....
, a
JFETThe junction gate field-effect transistor is the simplest type of field effect transistor. It can be used as an electronically-controlled switch or as a voltage-controlled resistance. Electric charge flows through a semiconducting channel between "source" and "drain" terminals...
model, and a model for a
junction diodeIn electronics a diode is a two-terminal electronic component which conducts electric current asymmetrically or unidirectionally; that is, it conducts current more easily in one direction than in the opposite direction. The term usually refers to a semiconductor diode, the most common type today,...
. In addition, it had many other elements: resistors, capacitors, inductors (including coupling), independent
voltageA voltage source is any device or system that produces an electromotive force between its terminals OR derives a secondary voltage from a primary source of the electromotive force. A primary voltage source can supply energy to a circuit while a secondary voltage source dissipates energy from a...
and
current sourceA current source is an electrical or electronic device that delivers or absorbs electric current. A current source is the dual of a voltage source...
s, ideal
transmission lineA transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic waves or acoustic waves, as well as electric power transmission....
s, and voltage and current controlled sources.
SPICE3 added more sophisticated MOSFET models, which were required due to advances in semiconductor technology.
In particular, the
BSIMBSIM refers to a family of MOSFET transistor models for integrated circuit design. Accurate transistor models are needed for electronic circuit simulation, which in turn is needed for integrated circuit design...
family of models were added, which were also developed at UC Berkeley.
Commercial and industrial SPICE simulators have added many other device models as technology advanced and earlier models became inaccurate. To attempt standardization of these models so that a set of model parameters may be used in different simulators, an industry working group was formed, the
Compact Model CouncilThe Compact Model Council is a working group in the Electronic Design Automation industry formed to choose, maintain and promote the use of standard models. Commercial and industrial analog simulators need to add device models as technology advances and earlier models become inaccurate...
, to choose, maintain and promote the use of
standard models. The standard models today include
BSIM3,
BSIM4,
BSIMSOI,
PSP,
HICUM, and
MEXTRAM.
Input and output: Netlists, schematic capture and plotting
SPICE2 took a text
netlistThe word netlist can be used in several different contexts, but perhaps the most popular is in the field of electronic design. In this context, a "netlist" describes the connectivity of an electronic design....
as input and produced line-printer listings as output, which fit with the computing environment in 1975. These listings were either columns of numbers corresponding to calculated outputs (typically voltages or currents), or line-printer
character "plots"ASCII art is a graphic design technique that utilizes computers for presentation and consists of pictures pieced together from the 95 printable characters defined by the ASCII Standard from 1963 and ASCII compliant character sets with proprietary extended characters...
. SPICE3 retained the netlist for circuit description, but allowed analyses to be controlled from a
command-lineA command-line interpreter is a computer program that reads lines of text entered by a user and interprets them in the context of a given operating system or programming language....
interface similar to the
C shellThe C shell is a Unix shell developed by Bill Joy for the BSD Unix system. The scripting syntax is modeled after the C programming language. Earlier releases of OpenBSD provided the C shell as the default shell on the system. The C shell was derived from the 6th Edition Unix Thompson shell which...
. SPICE3 also added basic X-Window plotting, as
UNIXUnix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
and engineering
workstationA workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...
s became common.
Vendors and various free software projects have added
schematic captureSchematic capture or schematic entry is a step in the design cycle of electronic design automation at which the electronic diagram, or electronic schematic of the designed electronic circuit is created by a designer...
front-ends to SPICE, allowing a schematic diagram of the circuit to be drawn and the netlist to be automatically generated. Also,
graphical user interfaceA graphical user interface is a type of user interface item that allows people to interact with programs in more ways than typing such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment with images rather than...
s were added for selecting the simulations to be done and manipulating the voltage and current output vectors. In addition, very capable graphing utilities have been added to see waveforms and graphs of parametric dependencies. Several free versions of these extended programs are available, some as introductory
limited packagesPSpice is a SPICE analog circuit and digital logic simulation software that runs on personal computers, hence the first letter "P" in its name. It was developed by MicroSim and is used in electronic design automation. MicroSim was bought by OrCAD which was subsequently purchased by Cadence Design...
, and some
without restrictionsLinear Technology Corporation , founded in 1981 by Robert Swanson and Bob Dobkin, designs, manufactures and markets a broad line of standard high performance integrated circuits...
.
See also
- Circuit simulators with articles on Wikipedia are listed in :Category:Electronic circuit simulators
- Advanced Design System Transient Convolution Simulator
Advanced Design System is an electronic design automation software system produced by Agilent EEsof EDA , a unit of Agilent Technologies...
- Input Output Buffer Information Specification
IBIS is a method of providing information about the input/output buffers of an integrated circuit to the outside world. It is an EIA standard....
(IBIS)
- List of free electronics circuit simulators (stub )
- PSPICE
PSpice is a SPICE analog circuit and digital logic simulation software that runs on personal computers, hence the first letter "P" in its name. It was developed by MicroSim and is used in electronic design automation. MicroSim was bought by OrCAD which was subsequently purchased by Cadence Design...
- Spectre Circuit Simulator
Spectre is a SPICE-class circuit simulator. It provides the basic SPICE analyses and component models. It also supports the Verilog-A modeling language...
- Transistor models
Transistors are simple devices with complicated behavior. In order to ensure the reliable operation of circuits employing transistors, it is necessary to scientifically model the physical phenomena observed in their operation using transistor models. There exists a variety of different models that...
External links
Versions with source code available
Applications