Difference between revisions of "LTspice Genealogy - The Heritage of Simulation Ubiquity"
From LTwiki-Wiki for LTspice
(Added page outlining the history of the popularization of SPICE culminating in LTspice) |
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** Utilized implicit integration to accommodate widely spread time constants of an IC | ** Utilized implicit integration to accommodate widely spread time constants of an IC | ||
** Integrated DC operating point analysis, small-signal AC analysis and transient analysis | ** Integrated DC operating point analysis, small-signal AC analysis and transient analysis | ||
− | * Project presented by Ron Rohrer at the 1971 ISSCC , but the code was considered partially proprietary and was never publicly released | + | * Project presented by Ron Rohrer at the 1971 ISSCC[http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1050166], but the code was considered partially proprietary and was never publicly released |
== 1971: SPICE 1 (Simulation Program with IC Emphasis) - direct outgrowth of CANCER == | == 1971: SPICE 1 (Simulation Program with IC Emphasis) - direct outgrowth of CANCER == |
Revision as of 12:43, 15 July 2013
Contents
1969: Beginnings of CANCER (Computer Analysis of Nonlinear Circuits, Excluding Radiation)
- CANCER began as a derivative of a program that was the class project of a series of courses taught by Ron Rohrer with the approval and encouragement of Professor Donald O. Pederson
- Larry Nagel wrote the netlist parser and the analysis core and was student group leader
- Lynn Weber developed a noise analysis feature that utilized adjoint network techniques
- Bob Berry wrote the sparse matrix LU decomposition package
- CANCER project's key features:
- Was the first circuit simulator to utilize sparse matrix techniques
- Used Newton-Raphson iteration method heuristically modified for bipolar circuits
- Utilized implicit integration to accommodate widely spread time constants of an IC
- Integrated DC operating point analysis, small-signal AC analysis and transient analysis
- Project presented by Ron Rohrer at the 1971 ISSCC[1], but the code was considered partially proprietary and was never publicly released
1971: SPICE 1 (Simulation Program with IC Emphasis) - direct outgrowth of CANCER
- Ron Rohrer leaves UC Berkeley and further development of CANCER (renamed SPICE) became Larry Nagel's Masters project with Don Pederson taking over as faculty advisor
- KEY EVENT: Don Pederson insisted that all further work be releasable to the public domain
- SPICE 1 release's key features:
- Models for bipolar transistors were changed to Gummel-Poon equations
- JFET and Shichman-Hodges MOSFET devices added (for Dave Hodges' MOSFET design class)
- Fixed time step and strict Nodal Analysis (true voltage sources and inductors not supported)
- DC, AC, Transient, Noise, and Sensitivity Analyses in the same program
- Built-in models for diodes, bipolar transistors, MOSFETs, and JFETs
- Was about 6k lines of FORTRAN at first informal limited public release in late 1971
- Official public release was May 1972 with first formal paper presented by Don Pederson at the 16th Midwest Symposium on Circuit Theory, April 12, 1973
- SPICE 1 becomes industry standard simulation tool running on large mainframe computers
1972: SPICE 2 begins
- First version of SPICE 2 was Larry Nagel's Ph.D. project under Don Pederson
- Modified Nodal Analysis (MNA) added, enabling voltage sources and inductors for the first time
- Ellis Cohen added dynamic memory allocation
- Adjustable time-step control added, greatly speeding most simulations
- MOSFET and bipolar models overhauled and extended
- Was about 8k lines of FORTRAN when first released to the public domain in late 1974
- Larry Nagel departs for Bell Labs and his thesis becomes the SPICE 2 Users Guide
1975: Journey to SPICE 2G6 (the pinnacle FORTRAN version)
- Ellis Cohen becomes primary contributor with later help from Andrei Vladimirescu
- First of a series of public revision releases after Nagel's version 2B begin in 1978
- Along the way, sub circuits, poly sources and transmission lines are added
- Version 2G6 ends up implementing three MOSFET models:
- MOS 1 is a simplistic model described purely by ideal square-law I-V characteristics
- MOS 2 is an analytical model, MOS 3 is a semi-empirical model and both include second-order effects such as channel length modulation, sub threshold conduction, scattering limited velocity saturation, small-size effects, and charge-controlled capacitances
- 2G6 released to public domain in April 1983 (and is still available today from UC Berkeley)
- Many commercial simulators today are based on SPICE 2G6
1983: SPICE 3 begins
- Tom Quarles begins work, writing first version in RATFOR, a C-like preprocessor for FORTRAN
- Was fully converted to C in 1985 with first early versions released in March of that year
- Added models: MESFET, lossy transmission line and non-ideal switch
- Arbitrary behavioral voltage and current sources added
- Includes polynomial capacitors, inductors and voltage controlled sources
- Allowed the use of alphabetical node labels rather than only numbers
- Features a graphical interface for viewing results
- New version eliminates many convergence problems
- Added noise, distortion and pole-zero analysis, temperature sweeping, Monte Carlo and Fourier analysis
- Not fully compatible with SPICE 2G6
- Was about 135,000 lines of C code at first public release in 1989
- Final version at Berkeley, SPICE 3F5, released to public in 1993
- XSPICE was developed at Georgia Tech as an extension to the SPICE language to allow behavioral modeling of components
- Drastically improve the speeds of mixed-mode and digital simulations
1984: PSpice (micro Processor SPICE)
- Developed by MicroSim to run on the first IBM PC, initially released in January 1984
- Was the first commercial offspring of Berkeley SPICE to run directly on the PC platform
- Was the first SPICE program to gain wide acceptance in both industry and academia
- KEY EVENT: A zero cost (but node-limited) student version is introduced in 1988 – for the first time, SPICE becomes ubiquitous in the electrical engineering community
- Evolved from Berkeley SPICE 2G, but added many proprietary enhancements
- Probe, a waveform viewer module, was added when PC VGA graphics became available
- Schematics, a graphical front end, was added much later sometime in the early 1990s
The Road To LTspice
- 1981 Linear Technology Corporation founded
- 1991 DOS SwitcherCAD available (equation based)
- 1996 μPower SwitcherCAD available(simulation based)
1999: LTspice/SwitcherCAD III first released to public
2008: LTspice IV
Some possible noteworthy events/additions:
Ver 2 Jan03: graphical symbol editor hierarchical schematics Apr04: Chan inductor, undocumented behavioral inductor revealed