# SPICE

**SPICE** ("**Simulation Program with Integrated Circuit Emphasis**")^{[1]}^{[2]} is a general-purpose, open-source analog electronic circuit simulator.
It is a program used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.

Original author(s) | Laurence Nagel |
---|---|

Initial release | 1973 |

Written in | Fortran |

Type | Electronic circuit simulation |

License | Public-domain software |

Website | bwrcs |

Initial release | 1975 |
---|---|

Stable release | 2G.6
/ 1983 |

Written in | Fortran |

Type | Electronic circuit simulation |

License | BSD 3 Clause |

Website | bwrcs |

Original author(s) | Thomas Quarles |
---|---|

Initial release | 1989 |

Stable release | 3f.5
/ July 1993 |

Written in | C |

Type | Electronic circuit simulation |

License | BSD license |

Website | bwrcs |

## IntroductionEdit

Unlike board-level designs composed of discrete parts, it is not practical to breadboard integrated circuits before manufacture. Further, the high costs of photolithographic masks 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 Carlo 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 netlist describing the circuit elements (transistors, resistors, capacitors, etc.) and their connections, and translate^{[3]} this description into equations to be solved. The general equations produced are nonlinear differential algebraic equations which are solved using implicit integration methods, Newton's method and sparse matrix techniques.

## OriginsEdit

SPICE was developed at the Electronics Research Laboratory of the University of California, Berkeley by Laurence Nagel with direction from his research advisor, Prof. Donald Pederson. SPICE1 was largely a derivative of the CANCER program,^{[4]}
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 in the 1960s:^{[5]}
at these times many circuit simulators were developed under contracts with the United States Department of Defense 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.^{[6]}

SPICE1 was first presented at a conference in 1973.^{[7]} SPICE1 was coded in FORTRAN and used 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^{[8]} in 1975. SPICE2, also coded in FORTRAN, was a much-improved program with more circuit elements, variable timestep transient analysis using either the trapezoidal (second order Adams-Moulton method) or the Gear integration method (also known as BDF), equation formulation via modified nodal analysis^{[9]} (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^{[10]} was developed by Thomas Quarles (with A. Richard Newton as advisor) in 1989. It is written in C, uses the same netlist syntax, and added X Window System plotting.

As an early public domain software program with source code available,^{[11]} SPICE was widely distributed and used. Its ubiquity became such that "to SPICE a circuit" remains synonymous with circuit simulation.^{[12]} 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 US, but the source code is currently covered by the BSD license.

The birth of SPICE was named an IEEE Milestone in 2011; the entry mentions that SPICE "evolved to become the worldwide standard integrated circuit simulator."^{[13]} Nagel was awarded the *2019 IEEE Donald O. Pederson Award in Solid-State Circuits* for the development of SPICE.^{[14]}

## SuccessorsEdit

### Open-source successorsEdit

No newer versions of Berkeley SPICE have been released after version 3f.5 in 1993.^{[15]} Since then, the open-source or academic continuations of SPICE include: XSPICE,^{[16]} developed at Georgia Tech, which added mixed analog/digital "code models" for behavioral simulation, CIDER^{[17]} (previously CODECS), developed by UC Berkeley and Oregon State Univ., which added semiconductor device simulation, SPICE OPUS,^{[18]}^{[19]} developed and maintained by the University of Ljubljana is based on SPICE 3f.4 and on XSPICE, ngspice, based on SPICE 3f.5, XSPICE and CIDER.^{[20]}^{[21]}

### Commercial versions and spinoffsEdit

Berkeley 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,^{[22]} an interactive version on a timeshare service, National CSS. The most prominent commercial versions of SPICE include HSPICE (originally commercialized by Ashawna and Kim Hailey of Meta Software, but now owned by Synopsys) and PSPICE (now owned by Cadence Design Systems). The integrated circuit industry adopted SPICE quickly, and until commercial versions became well developed many IC design houses had proprietary versions of SPICE.^{[23]}

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 Devices, LTspice at Analog Devices (available to the public as freeware), Mica at Freescale Semiconductor, and TINA-TI^{[24]} at Texas Instruments. Both LTspice and TINA-TI come bundled with models from their respective company.^{[25]}^{[26]} Analog Devices offers a similar free tool called ADIsimPE (based on the SIMetrix/SIMPLIS^{[27]} implementation of SPICE).^{[28]} Other companies maintain internal circuit simulators which are not directly based upon SPICE, among them PowerSpice at IBM, TITAN at Infineon Technologies, Lynx at Intel Corporation, and Pstar at NXP Semiconductor.^{[citation needed]}

## Program features and structureEdit

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.^{[29]} Precursors to SPICE often had a single purpose: The BIAS^{[30]} program, for example, did simulation of bipolar transistor circuit operating points; the SLIC^{[31]} 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.

### AnalysesEdit

SPICE2 included these analyses:

- AC analysis (linear small-signal 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 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 analysis, pole-zero analysis, and small-signal distortion 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.^{[29]}

It is very important to use appropriate analyses with carefully chosen parameters. For example, application of linear analysis to nonlinear circuits should be justified separately. Also, application of transient analysis with default simulation parameters can lead to qualitatively wrong conclusions on circuit dynamics.^{[32]}

### Device modelsEdit

SPICE2 included many semiconductor device compact models: three levels of MOSFET model, a combined Ebers–Moll and Gummel–Poon bipolar model, a JFET model, and a model for a junction diode. In addition, it had many other elements: resistors, capacitors, inductors (including coupling), independent voltage and current sources, ideal transmission lines, active components and voltage and current controlled sources.

SPICE3 added more sophisticated MOSFET models, which were required due to advances in semiconductor technology. In particular, the BSIM 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 inadequate. 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 Council,^{[33]} to choose, maintain and promote the use of standard models. The standard models today include BSIM3, BSIM4, BSIMSOI, PSP, HICUM, and MEXTRAM.

### Exclusion for integrated photonic circuitsEdit

Traditional photonic device simulators apply direct methods to solve Maxwell's equations for the complete structure, whereas photonic circuit simulators are based on a segmentation into building blocks (BBs), each of which is represented at a logic level by a phothonic device, "coupled to other BBs by guided modes of optical waveguides". At the circuit-level modeling, a photonic integrated circuit (PIC) contain both electrical wires and optical signals, respectively described by voltage/current and by complex-valued envelope for the forward- and backward-propagating modes.^{[34]}

The building block netlist of both the photonic and electronic circuits, including their net and port connections, can be expressed in a SPICE format with some schematic editors, like the ones used for electronic design automation.^{[35]}

To reproduce the complete photonic signal information, without losing eventual optical phenomena, it is needed the real-time waveform of both the electric and the magnetic field for every mode or polarization in the waveguide.^{[clarification needed]} While SPICE works with 10^{−15} time steps, timescale datacommunications of ≈10–100 10^{−12} are common. To make the amount of information tractable, the modulation increases of complexity, having to encode both amplitude and phase, in a way similar as in the simulation of RF circuits.^{[36]}

However, Photonic Integrated Circuit simulators need to test multiple communication channels in match with different Carrier frequencies, or equivalently more amplitudes in any single channel, a type of sophisticated signal that is unsupported on the SPICE program features and structure as described above.^{[34]} At 2019, SPICE can't be used to "simulate photonics and electronics together in a photonic circuit simulator",^{[37]} and thus it isn't yet considered as a test simulator for photonic integrated circuits.

### Input and output: Netlists, schematic capture and plottingEdit

SPICE2 took a text netlist 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". SPICE3 retained the netlist for circuit description, but allowed analyses to be controlled from a command-line interface similar to the C shell. SPICE3 also added basic X plotting, as UNIX and engineering workstations became common.

Vendors and various free software projects have added schematic capture front-ends to SPICE, allowing a schematic diagram of the circuit to be drawn and the netlist to be automatically generated. Also, graphical user interfaces 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 packages, and some without restrictions.

### Transient analysisEdit

Since transient analysis is dependent on time, it uses different analysis algorithms, control options with different convergence-related issues and different initialization parameters than DC analysis. However, since a transient analysis first performs a DC operating point analysis (unless the UIC option is specified in the .TRAN statement), most of the DC analysis algorithms, control options, and initialization and convergence issues apply to transient analysis.

#### Initial conditions for transient analysisEdit

Some circuits, such as oscillators or circuits with feedback, do not have stable operating point solutions. For these circuits, either the feedback loop must be broken so that a DC operating point can be calculated or the initial conditions must be provided in the simulation input. The DC operating point analysis is bypassed if the UIC parameter is included in the .TRAN statement. If UIC is included in the .TRAN statement, a transient analysis is started using node voltages specified in an .IC statement. If a node is set to 5 V in a .IC statement, the value at that node for the first time point (time 0) is 5 V.

You can use the .OP statement to store an estimate of the DC operating point during a transient analysis.

```
.TRAN 1ns 100ns UIC
.OP 20ns
```

The .TRAN statement UIC parameter in the above example bypasses the initial DC operating point analysis. The .OP statement calculates transient operating point at t = 20 ns during the transient analysis.

Although a transient analysis might provide a convergent DC solution, the transient analysis itself can still fail to converge. In a transient analysis, the error message "internal timestep too small" indicates that the circuit failed to converge. The convergence failure might be due to stated initial conditions that are not close enough to the actual DC operating point values.

## See alsoEdit

## ReferencesEdit

**^**Nagel, L. W, and Pederson, D. O.,*SPICE (Simulation Program with Integrated Circuit Emphasis)*, Memorandum No. ERL-M382, University of California, Berkeley, Apr. 1973**^**Nagel, Laurence W.,*SPICE2: A Computer Program to Simulate Semiconductor Circuits*, Memorandum No. ERL-M520, University of California, Berkeley, May 1975**^**Warwick, Colin (May 2009). "Everything you always wanted to know about SPICE* (*But were afraid to ask)" (PDF).*EMC Journal*. Nutwood UK Limited (82): 27–29. ISSN 1748-9253.**^**Nagel, L. W.; Rohrer, R. A. (August 1971). "Computer Analysis of Nonlinear Circuits, Excluding Radiation".*IEEE Journal of Solid-State Circuits*.**SC-6**: 166–182. Bibcode:1971IJSSC...6..166N. doi:10.1109/JSSC.1971.1050166.^{[dead link]}**^**Life of SPICE Archived February 4, 2012, at the Wayback Machine**^**Perry, T. (June 1998). "Donald O. Pederson".*IEEE Spectrum*.**35**: 22–27. doi:10.1109/6.681968.**^**2nd spice1 ref**^**2nd spice2 ref**^**Ho, Ruehli, and Brennan (April 1974). "The Modified Nodal Approach to Network Analysis".*Proc. 1974 Int. Symposium on Circuits and Systems, San Francisco*. pp. 505–509. Archived from the original on 2011-05-15.CS1 maint: multiple names: authors list (link)**^**Quarles, Thomas L.,*Analysis of Performance and Convergence Issues for Circuit Simulation*, Memorandum No. UCB/ERL M89/42, University of California, Berkeley, Apr. 1989.**^**history-of-spice Archived October 9, 2016, at the Wayback Machine on allaboutcircuits.com*"The origin of SPICE traces back to another circuit simulation program called CANCER. Developed by professor Ronald Rohrer of U.C. Berkeley along with some of his students in the late 1960s, CANCER continued to be improved through the early 1970s. When Rohrer left Berkeley, CANCER was re-written and re-named to SPICE, released as version 1 to the public domain in May of 1972. Version 2 of SPICE was released in 1975 (version 2g6—the version used in this book—is a minor revision of this 1975 release). Instrumental in the decision to release SPICE as a public-domain computer program was professor Donald Pederson of Berkeley, who believed that all significant technical progress happens when information is freely shared. I for one thank him for his vision."***^**Pescovitz, David (2002-05-02). "1972: The release of SPICE, still the industry standard tool for integrated circuit design". Lab Notes: Research from the Berkeley College of Engineering. Retrieved 2007-03-10.**^**"List of IEEE Milestones".*IEEE Global History Network*. IEEE. Retrieved 4 August 2011.**^**Donald O. Pederson Solid-State Circuits Award, IEEE Solid-State Circuits Society, June 2018**^**"The Spice Page". Berkeley University. Retrieved 2019-07-08.**^**Code-level modeling in XSPICE, F. L. Cox e.a., Proceedings IEEE International Symposium on Circuits and Systems, 1992 (ISCAS 92), vol. 2, pp. 871-874, 10–13 May 1992**^**CODECS: A Mixed-Level Circuit and Device Simulator, K. Mayaram, Memorandum No. UCB/ERL M88/71, Berkeley, 1988, http://www.eecs.berkeley.edu/Pubs/TechRpts/1988/ERL-88-71.pdf**^**"SPICE OPUS". University of Ljubljana. Retrieved 2019-07-08.**^**Tadej Tuma and Árpád Bűrmen (2009).*Circuit Simulation with SPICE OPUS THeory and Practice*. Birkhäuser Press. p. 400. doi:10.1007/978-0-8176-4867-1. ISBN 978-0-8176-4866-4.**^**ngspice, current status and future developments, H. Vogt, FOSDEM, Brussels 2019, https://fosdem.org/2019/schedule/event/ngspice/**^**"ngspice - an open source mixed signal circuit simulator". Free Silicon Foundation (F-Si). Retrieved 2019-07-08.**^**Vladimirescu, Andrei,*SPICE -- The Third Decade*, Proc. 1990 IEEE Bipolar Circuits and Technology Meeting, Minneapolis, Sept. 1990, pp. 96–101**^**K. S. Kundert,*The Designer’s Guide to SPICE and Spectre*, Kluwer. Academic Publishers, Boston , 1995**^**SPICE-Based Analog Simulation Program - TINA-TI - TI Software Folder Archived October 19, 2016, at the Wayback Machine**^**Art Kay (2012).*Operational Amplifier Noise: Techniques and Tips for Analyzing and Reducing Noise*. Elsevier. p. 41. ISBN 978-0-08-094243-8.**^**Ron Mancini (2012).*Op Amps for Everyone*. Newnes. p. 162. ISBN 978-0-12-394406-1.**^**SIMertrix/SIMPLIS Archived May 17, 2016, at the Portuguese Web Archive**^**[1] Archived July 6, 2014, at the Wayback Machine- ^
^{a}^{b}Nagel, L., Is it Time for SPICE4? Archived September 26, 2006, at the Wayback Machine, 2004 Numerical Aspects of Device and Circuit Modeling Workshop, June 23–25, 2004, Santa Fe, New Mexico. Retrieved on 2007-11-10 **^**McCalla and Howard (February 1971). "BIAS-3 – A program for nonlinear D.C. analysis of bipolar transistor circuits".*IEEE Journal of Solid-State Circuits*.**6**(1): 14–19. Bibcode:1971IJSSC...6...14M. doi:10.1109/JSSC.1971.1050153.^{[dead link]}**^**Idleman, Jenkins, McCalla and Pederson (August 1971). "SLIC—a simulator for linear integrated circuits".*IEEE Journal of Solid-State Circuits*.**6**(4): 188–203. Bibcode:1971IJSSC...6..188I. doi:10.1109/JSSC.1971.1050168.CS1 maint: multiple names: authors list (link)^{[dead link]}**^**Bianchi, Giovanni (2015). "Limitations of PLL simulation: hidden oscillations in SPICE analysis". arXiv:1506.02484. Bibcode:2015arXiv150602484B. doi:10.1109/ICUMT.2015.7382409. Cite journal requires`|journal=`

(help)**^**"CMC - Compact Model Council". GEIA. Archived from the original on May 11, 2011.- ^
^{a}^{b}André Richter; Sergei Mingaleev; Igor Koltchanov (23 June 2015). "Automated design of large-scale photonic integrated circuits".*The International society for optics and photonics*: 1–2. doi:10.1117/2.1201506.005982 (inactive 2019-12-06). Archived from the original on 18 July 2019. **^**Las_Phot_Rev_1700237, p. 9**^**Las_Phot_Rev_1700237, p. 18**^**Wim Bogaerts; Lukas Chrostowski (March 2018).*Silicon Photonics Circuit Design: Methods, Tools and Challenges*.*Laser Photonics Rev*.**12**. Weinheim: Wiley-Wch Werlag. p. 9. doi:10.1002/lpor.201700237. hdl:1854/LU-8578535. Las_Phot_Rev_1700237. Archived from the original on 18 July 2019.