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Updated FAQ - Preliminary version - not for release

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Ngspice F.A.Q.Version 1.4
Maintained by Paolo Nenzi <p.nenzi@ieee.org>
Last update: 27-01-2004
Ngspice F.A.Q.Version 1.5 (rework-18 release)
Maintained by Paolo Nenzi
Last update: 5-11-2008
This document contains the Frequently Asked Questions (and Answers)
for ngspice project.
@ -11,16 +11,17 @@
1. INTRODUCTION AND GENERAL INFORMATION
1.1 What is ngspice?
1.2 Why resurrecting Berkeley's Spice?
1.3 What is the project's goal?
1.4 What you are going to do?
1.5 Legal issues
1.6 What mailing lists exist for ngspice?
1.7 Are the mailing lists archived anywhere?
1.8 What newsgroups exist for ngspice?
1.9 Where can I get a copy of ngspice?
1.10 Where should I look on the World Wide Web for ngspice stuff?
1.11 Where should I look on the World Wide Web for Spice documentation?
1.2 What is tclspice ?
1.3 Why resurrecting Berkeley's Spice?
1.4 What is the project's goal?
1.5 What you are going to do?
1.6 Legal issues
1.7 What mailing lists exist for ngspice?
1.8 Are the mailing lists archived anywhere?
1.9 What newsgroups exist for ngspice?
1.10 Where can I get a copy of ngspice?
1.11 Where should I look on the World Wide Web for ngspice stuff?
1.12 Where should I look on the World Wide Web for Spice documentation?
2. DEVELOPMENT
2.1 What is the current version?
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1.1 What is ngspice?
1.1 What is ngspice ?
Ngspice is a mixed-level/mixed-signal circuit simulator based on three
open source software packages: Spice3f5, Cider1b1 and Xspice:
- Spice3 is the most famous and used circuit simulator. It was
developed University of California at Berkeley (UCB), by "a cast of
thousand" (as they say).
- Spice3 is a widely used circuit simulator. It was developed by the
University of California at Berkeley (UCB), by "a cast of thousand"
(as they say) initially under the guide of Donald O. Peterson.
- Cider is a mixed-level simulator that already includes Spice3f5 and
adds a device simulator to it: DSIM. Cider couples the circuit level
@ -75,112 +76,58 @@
ngspice program.
1.2 Why resurrecting Berkeley's Spice?
1.2 What is tclspice ?
Tclspice is a circuit simulator that embeds ngspice and provides a
tcl/tk interface to the user. Tclspice is both a batch and interactive
simulator and a building block for simulator applications. Analyses can
be run from a tcl script and vector plotted or post processed using tcl
or a small GUI can be built to analyze a circuit or a set of circuits.
Tclspice is obtained compiling ngspice activating an additional option.
1.3 Why resurrecting Berkeley's Spice?
Berkeley's Spice can be considered the father of most circuit
simulators available today. It is an old but still good piece of
software, it may not be the fastest or the most reliable but it's
free, it's available in source code and most of the electrical
simulators inherited it's syntax. On the more technical side, spice3
uses good numerical algorithms (most commercial implementations have
only strengthened them), implements most of the models for MOSFET
submicron designs and has a powerful set of analyses. On the more
"social" side, spice3 it's well introduced in the academic
environment.
simulators inherited it's syntax. Spice3 is based on proven numerical
algorithms (most commercial implementations have only strengthened
them), implements most of the models for MOSFET submicron design
and has a powerful set of analyses. The readily availability of
its source code in the past made this simulator the de-facto standard.
1.3 What is the project's goal?
1.4 What is the project's goal?
The project goal evolved during project development, at first the
final goal was to develop a reliable, fast and friendly circuit
simulator for mixed signal/mixed level simulation. During
development it become apparent that to reach the goal a complete
rewrite of spice was needed. Since it was almost absurd to rewrite
Spice and since a new simulator was already under development:
ACS (Al's Circuit Simulator), now GNUCap (GNU Circuit Analysis
package), the goal of nspice became less utopical: merge
Spice3f5, Xspice and Cider into a mixed-signal/mixed-level simulator
that can be used as a reliable engine.
Ngspice is both a maintenance and enhancement project. It is a maintenance
project because it aims to provide the free EDA community the best spice3
simulator available. This means fixing bugs, adding new features but always
in the spice3 framework. Achieving compatibility with commercial spice based
simulators and provide users the latest devices models are important goals
of the project. Improvements in the postprocessing (data handling
capabilities) and user interface are other goals.
1.4 What you are going to do?
1.5 What you are going to do?
We are going to develop a mixed-signal/mixed-level circuit simulation
program integrating three different spice based simulators:
Spice, Xspice and Cider.
An official roadmap for ngspice was never drawn. Contributions made by
developers drive ngspice development and the roadmap is built day by
day by developers writing on the lists. Ngspice development activity
can be summarized in 3 points:
Xspice is a mixed-signal circuit simulator developed by GTRI (Georgia
Tech Research Institute) at Georgia Institute of Technology. Xspice
was originally developed as an extension over Spice3c1. Xspice
introduces code modeling and a digital simulator into ngspice.
The "home site" of Xspice is:
http://users.ece.gatech.edu/~mrichard/Xspice/
Cider is a mixed-level circuit and device simulator based on Spice3f5
that couples a device simulator (DSIM) to Spice. More information can
be found at:
http://www-cad.eecs.berkeley.edu/Software/cider.html
The merging process is done in parallel with bug fixing and improvement
of the three simulators. The improvements are concentrated into 6
directions:
+ Compact models: the improvements in compact models will address
mainly the implementation of additional effects not available
in the original code. Device specific improvements are documented
on ngspice's documentation and in the DEVICE file in project's
tarball.
Improvements that affects all devices already implemented are:
"dtemp" option to set instance's temperature relative to the circuit
one and "m" parallel multiplier to simulate an arbitrary number of
instances of the same kind connected in parallel.
Planned improvements are the development of a dynamic loading
mechanism for compact models, to avoid loading in memory devices
that are not needed, and SOAR (Safe Operating ARea) checks to
identify situations in which devices are used out of their
safety areas.
+ Simulator's analyses: this is a low priority area. Planned improvements
include the implementation of parametric analyses, to analyse the
behaviour of the circuit as a parameter changes. Parameter sweep,
Monte Carlo and Worst Case fall in this category. Network analysis
(double bipole parameters extraction) is another planned improvement.
+ Numerical analysis code: the improvements within the numerical code
must be done with extreme care. Planned improvements are, the
replacement of the Sparse library with the latest code Kenneth Kundert
has released, available at:
http://sourceforge.net/projects/sparse
Other planned improvements, but with very low priority, includes the
use SuperLU library as possible Sparse library replacement (the
library is available at http://crd.lbl.gov/~xiaoye/SuperLU) and the
introduction of continuation metohds to aid DC convergence.
+ Spice language: The language used to input the circuit to the simulator
has been extended and now allows the user to input parametric values
for components (the numparam library). This is an experimental feature
that will be improved in the future. Planned improvements includes the
support for loading more than one circuit, netlist manipulation via
command line (adding and removing instances) and the implementation
of a command history using the libedit library, available at:
http://sourceforge.net/projects/libedit
+ Frontend: The design of a new spice frontend has not been successful
and now is orphaned, since the is no interests and many free and
commercial frontends are available. There is no planned improvement
here.
+ Compatibility: Ngspice should be compatible with commercial products,
thus allowing people to use the netlist generated for such tools. As
most of the commercial simulators avaiable tracked each other in netlist
language, this should not be an impossible task. The most important goal
here is to provide a reliable support for model libraries coming from
foundries.
+ Compact models: The interest in using ngspice is intimately connected
to the available models. To provide the latest models available for
active and passive devices is a fundamental goal of the project. In
this direction we are integrating ADMS model compiler into ngspice.
+ Documentation: Commercial simulators come with very good manuals
containing tutorials, description of models equations, example of
@ -192,54 +139,35 @@
documentation will always be left slightly behind.
1.5 Legal issues
1.6 Legal issues
Ngspice merges three different simulators: spice and cider are covered
with the "old" BSD license, Xspice by its own license. The ngspice
license will be then the BSD license.
Since the "old" BSD license is not compatible with the GPL library
it is not possible to link the ngspice with GPL'ed code, as is
written in:
http://www.gnu.org/philosophy/bsd.html
The group developing ngspice has written to Berkeley's copyright
holders asking to change the license to the new BSD, which has the
incompatibility removed, but without success.
Ngspice will not be released under GPL license and, no GPL code can be
linked into ngspice (as in the original Spice3f) without breaking GPL.
Ngspice, starting from release rework-18 is released under BSD/LGPL
license. Part of the code are covered by other compatible licenses:
spice3 and cider are BSD, xspice is Public Domain and TCLSPICE is
LGPL and the copyright is of their respective owners (need to write better)
1.6. What mailing lists exist for ngspice?
1.7. What mailing lists exist for ngspice?
There are three mailing lists dedicated to the ngspice project.
There are two general mailing lists dedicated to the ngspice project.
Users mailing list: <ngspice-users@lists.sourceforge.net>
This list is for ngspice users, examples, problems, bug reports
and general discussion on ngspice can be sent here
and general discussion on ngspice can be sent here.
Developers mailing list: <ngspice-devel@lists.sourceforge.net>
The list dedicated to ngspice development. Developers shold
subscribe here, to follow the program development. May be used
to send patches, and technical discussion on ngspice.
Frontend mailing list: <ngspice-frontends@lists.sourceforge.net>
Almost orphaned, this list should be used to discuss issues about
the realization of a graphical frontend to ngspice.
Send an empty message to the following addresses to get information
on subscription.
<ngspice-users-help@lists.sourceforge.net>
<ngspice-devel-help@lists.sourceforge.net>
<ngspice-frontends-help@lists.sourceforge.net>
1.7. Are the mailing lists archived anywhere ?
1.8. Are the mailing lists archived anywhere ?
Yes, the lists are archived. There are two places where to look for
archives. The project started on the IEEE Central and South Italy
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http://ngspice.sourceforge.net/lists.html
1.8. What newsgroups exist for ngspice?
1.9. What newsgroups exist for ngspice?
There is no ngspice specific newsgroup. Anyway ngspice threads appear
on newsgroups dedicated to circuit simulation and electronic design.
@ -264,38 +192,36 @@
comp.lsi.cad
1.9. Where can I get a copy of ngspice?
1.10. Where can I get a copy of ngspice?
You can download ngspice from:
http://sourceforge.net/projects/ngspice
1.10. Where should I look on the World Wide Web for ngspice stuff?
1.11. Where should I look on the World Wide Web for ngspice stuff?
Look at the official Ngpice Web Page:
http://ngspice.sourceforge.net
1.11. Where should I look on the World Wide Web for Spice documenta-
tion?
1.12. Where should I look on the World Wide Web for Spice documenta-
tion?
There are a lot of Internet sites that have information on spice, the
best way is to point to your preferred search engine. Some interesting
sites are:
The Spice Home Page:
Pages on Spice:
http://bwrc.eecs.berkeley.edu/Classes/IcBook/SPICE/
http://embedded.eecs.berkeley.edu/pubs/downloads/spice/index.htm
Xspice Page:
http://users.ece.gatech.edu/~mrichard/Xspic
http://users.ece.gatech.edu/~mrichard/Xspice
Cider Page:
http://www-cad.eecs.barkeley.edu/Software/cider.html
Spice benchmarks:
http://www.cbl.ncsu.edu/pub/Benchmark_dirs
http://embedded.eecs.berkeley.edu/pubs/downloads/cider/index.htm
@ -306,11 +232,7 @@
The latest version released is:
* ngspice-rework-15 (released on 10/12/2001)
The development version is:
* ngspice-rework-15pre3 (released on 28/01/2004)
* ngspice-rework-18 (released on 1/12/2008)
2.2. What are the latest features in the current release?
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New features:
+ Improved bipolar devices (Diode and bjt)
+ Improved BSIM3 and BSIM4
+ VBIC and HiSIM compact models
+ Cider and Xspice inclusion
+ More flexibility in net names
+ Parameter substitution in netlist
+ Support for .lib and .param statements
+ Improved netlisting capabilites to support more complex model cards
+ Global net names
+ Mosfet model binning
Bug fixes:
+ Many memory leaks closed
+ Control language works as expected
+ Fixes in the control language
2.3. What does it looks like?