ngspice/FAQ

  Ngspice F.A.Q.Version 1.0
  Maintened by Paolo Nenzi <p.nenzi@ieee.org>
  Last update: 05/12/2001

  This document contains the Frequently Asked Questions (and Answers)
  for ngspice project.
  ______________________________________________________________________

  Table of Contents


  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?

  2. DEVELOPMENT
     2.1 What is the current version?
     2.2 What are the latest features in the current release?
     2.3 What does it look like?
     2.4 Who are the authors of ngspice?
     2.5 How can I report a bug/request for a feature?
     2.6 How can I join the development?

  3. SOLUTIONS TO COMMON MISCELLANEOUS PROBLEMS
     3.1 What systems are supported?
     3.2 I get errors when I try to compile the source code, why?
     3.3 This document didn't answer my question. Where else can I look for an answer?

  4. ADMINISTRATIVE INFORMATION AND ACKNOWLEDGEMENTS
     4.1 Feedback
     4.2 Formats in which this FAQ is available
     4.3 Authorship and acknowledgements
     4.4 Disclaimer and Copyright


  ______________________________________________________________________

  11..  IINNTTRROODDUUCCTTIIOONN AANNDD GGEENNEERRAALL IINNFFOORRMMAATTIIOONN



  11..11..  WWhhaatt iiss nnggssppiiccee??

  Ngspice is the name of a project and of a program in the project.
  Spice is the famous circuit simulator developed by the CAD Group of
  the University of California at Berkeley (UCB). The NG prefix has a
  lot of meanings: Next Generation, New Good, etc. Choose or invent the
  one you prefer. The ngspice project aims to improve the capabilities
  of the Spice3 circuit simulator. The heart of the project is the
  ngspice program, a circuit simulator derived from spice3f5.


  11..22..  WWhhyy rreessuurrrreeccttiinngg BBeerrkkeelleeyy''ss SSppiiccee??

  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.


  11..33..  WWhhaatt iiss tthhee pprroojjeecctt''ss ggooaall??


  The final goal of ngspice project is to develop a reliable, fast and
  friendly circuit simulator for mixed signal/mixed level simulation.
  Easy isn't it? ;-).


  11..44..  WWhhaatt yyoouu aarree ggooiinngg ttoo ddoo??


  We are going to develop a circuit simulation program. The line of
  development follows two parallel paths:

  1. EEnnhhaanncceemmeennttss aanndd bbuugg--ffiixxiinngg ooff tthhee oorriiggiinnaall ssppiiccee33ff55 ccooddee..

  2. DDeevveellppppmmeenntt ooff aa nneeww GGPPLL''eedd ssiimmuullaattoorr..

     The first phat will lead to a better spice3f5 and nothing more than
     this, while the second one will bring us a new simulator,
     compatible with its father but more expandable and presumably
     faster and numerically stronger.

  There is another project in ngspice: the development of one or more
  frontend to the new simulator. One of the key issues of our project is
  to let users design the front end they want, using the widget set and
  the language they prefer. For this reason ngspice differs a lot from
  spice3f5: in ngspice there is a clear distinction between the front
  end and the back end. In ngspice the front end takes care of the
  interaction with the user.  It is  back-end's task to maintain the
  object database, to exchange data with the simulator, etc.

  There are various improvements we are planning, some follows:

  1. TThhee ffrraammeewwoorrkk ((oorr GGrraapphhiicc UUsseerr IInntteerrffaaccee)):: Spice is (and should
     continue to be) a command line or a text tool, but this makes very
     difficult to design large circuits. To overcome this difficulty, a
     schematic entry tool and a waveform viewer tools are needed.
     Nevertheless, there are other tools that can be useful: a parts
     database, an editor which higlights the syntax, a symbol editor,
     etc. Most of these program already exists in the open source world,
     so they need only to be integrated in a common EDA environment.

  2. DDooccuummeennttaattiioonn:: Commercial simulators have very good manuals with
     tutorials, models equations explained, example of use, suggestions,
     etc. This line of development has the task of providing the final
     spice user with an ordered and comprehensive set of information on
     the program and its features. The documentation should be useful
     for the student as well as for the circuit professional.

  3. IImmpprroovveemmeennttss ttoo tthhee SSppiiccee ccooddee:: This is the hard part. The target
     of this direction is to make ngspice a commercial grade simulator.
     This means improving it's speed, its numerical strenght, include
     the latest models available and some other important features:

     +o  Numerical Algorithms:

        +o  More stable algorithms for integration (as Runge-Kutta
           Methods (?) ).

        +o  Better convergence in Operating Point Calculation adding a
           modified version of Fixed-Point Homotopy to the Newton-
           Raphson algorithm,

     +o  Devices:

        +o  Behavioral device: enhance the B device of spice3 to accepts
           IF THEN ELSE conditions, and digital keywords like DELAY,
           HIGHV, LOWV, etc. to simulate simple digital macromodels.

        +o  Dynamically Loadable Devices: reduce the memory occupied by
           the simulator by using shared object code for devices. Each
           device is a .so library that is inserted only if the circuit
           contains an element modeled by the device. If we are
           simulating CMOS, we do not need BJT or SOI (in most of the
           situations).

        +o  Code Level Modeling: let users write their devices in C and
           use them in the simulator.

        +o  Improving device: include additional parameters to some
           devices as HDIF, LDIF, etc.

     +o  New types of analysis, oriented to circuits syntesis and
        optimization:

        +o  Network analysis: given four nodes, extract z,y,s and the
           other double bipole paramters.

        +o  Monte Carlo analysis: statistical simulation based on device
           tolerances.

        +o  Worst Case analysis: find the worst case of operation of a
           given circuit based on device parameters tolerances.

        +o  Parametric analysis: repeat an analysis when one or more
           parameters assumes different values.

     +o  Faster handling of sparse matrices.

     +o  Possibility to mesure circuit pameters, like the delay between
        two nodes, etc.

     +o  Whatever else can be judged useful.


  11..55..  LLeeggaall iissssuueess

  The improved spice3f5 will be relased under the original Berkeley's
  lincese. The new simulator will be released as GPL. Make ngspice a GPL
  program, allow us to link a lot of good code laying on the net and
  obviously contribute to the GPL community.


  11..66..  WWhhaatt mmaaiilliinngg lliissttss eexxiisstt ffoorr nnggssppiiccee??

  There are three mailing lists dedicated to the ngspice project. 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>



  11..77..  AArree tthhee mmaaiilliinngg lliissttss aarrcchhiivveedd aannyywwhheerree??

  Yes, the list are archived. Look at the project's web site to access
  archives.


  11..88..  WWhhaatt nneewwssggrroouuppss eexxiisstt ffoorr nnggssppiiccee??

  None. Sorry.


  11..99..  WWhheerree ccaann II ggeett aa ccooppyy ooff nnggssppiiccee??

  You can download ngspice from:

  <http://sourceforge.net/projects/ngspice>


  11..1100..  WWhheerree sshhoouulldd II llooookk oonn tthhee WWoorrlldd WWiiddee WWeebb ffoorr nnggssppiiccee ssttuuffff??

  Look at the official NG-Spice Web Page
  <http://ngspice.sourceforge.net>


  11..1111..  WWhheerree sshhoouulldd II llooookk oonn tthhee WWoorrlldd WWiiddee WWeebb ffoorr SSppiiccee ddooccuummeennttaa--
  ttiioonn??

  50 Circuits analyzed with SPICE
  <http://www.dacafe.com/DACafe/EDATools/EDAbooks/SpiceHandBook/01_TOC.html>

  <http://www.dacafe.com/DACafe/EDATools/EDAbooks/SMPS/SMPS.htm>


  22..  DDEEVVEELLOOPPMMEENNTT



  22..11..  WWhhaatt iiss tthhee ccuurrrreenntt vveerrssiioonn??

  rework-14 (released on 10/12/2001)


  22..22..  WWhhaatt aarree tthhee llaatteesstt ffeeaattuurreess iinn tthhee ccuurrrreenntt rreelleeaassee??

  New features:

  +o  New functions for vectors: vecmax (find max element in a vector),
     vecmin (find minimum element in a vector), vecd (differentiate a
     vector).

  +o  BSIM 4 and support EKV models.

  Bug fixes:

  +o  Some memory leaks closed.

  +o  Error reporting more verbose



  22..33..  WWhhaatt ddooeess iitt llooookk lliikkee??

  This is a command line utility, no screenshots!


  22..44..  WWhhoo aarree tthhee aauutthhoorrss ooff nnggssppiiccee??

  The development is open to anyone who wish to contribute.

  People who contributed are (in alphabetical order):

  +o  Daniele Foci <dfoci@ieee.ing.uniroma1.it>

  +o  Paolo Nenzi <pnenzi@ieee.ing.uniroma1.it>

  +o  Arno Peters <A.W.Peters@ieee.org>

  +o  Serban-Mihai Popescu <serbanp@ix.netcom.com>

  +o  Emmanuel Rouat <emmanuel.rouat@wanadoo.fr>

  +o  Michael Widlok <twidlok@uci.agh.edu.pl>


  This list is surely incomplete (due to open development group), there
  are many people who contributed with improvements, pieces of code, bug
  fixes, etc. If you have contributed and do not appear, write to:

  <ng-spice@ieee.ing.uniroma1.it>

  and ask to be included.


  22..55..  HHooww ccaann II rreeppoorrtt aa bbuugg//rreeqquueesstt ffoorr aa ffeeaattuurree??

  Look at the projects summary page: ngspice summary page

  22..66..  HHooww ccaann II jjooiinn tthhee ddeevveellooppmmeenntt??

  To join the development just code the feature you want to add and send
  your patch in the mailing list.  Before you start coding check the
  latest development release of ngspice from our CVS. It might be that
  your feature has already been implemented.


  33..  SSOOLLUUTTIIOONNSS TTOO CCOOMMMMOONN MMIISSCCEELLLLAANNEEOOUUSS PPRROOBBLLEEMMSS



  33..11..  WWhhaatt ssyysstteemmss aarree ssuuppppoorrtteedd??

  This is the updated list:

  Hardware           O.S. Version            Compiler       Functional?
  ----------------   ----------------------- -------------- -----------
  ????               HP-UX 10.10             gcc 2.95.2     yes
  IBM Risc 6000      ???                     lcc            no
  i386               Debian GNU/Linux 2.1    gcc 2.7.2      yes
  i386               Red Hat Linux 5.2       gcc 2.7.2      yes
  i386               SuSE Linux 6.0          gcc 2.7.2      yes
  i386               Linux (SuSE)            gcc            yes
  UltraSPARC         Solaris 7               gcc            yes
  UltraSPARC         Solaris 7               SUN Workshop   ?



  MS-Dos, VMS and MacOS are no longer supported.


  33..22..  II ggeett eerrrroorrss wwhheenn II ttrryy ttoo ccoommppiillee tthhee ssoouurrccee ccooddee,, wwhhyy??

  [not written yet]


  33..33..  TThhiiss ddooccuummeenntt ddiiddnn''tt aannsswweerr mmyy qquueessttiioonn.. WWhheerree eellssee ccaann II llooookk
  ffoorr aann aannsswweerr??

  Read old messages from the mailing list archive, search the web site
  or read the docs.  Upgrade to the latest version of ngspice, many
  problems are fixed in the new versions.  If you still can't find an
  answer, post your question to the mailing list.


  44..  AADDMMIINNIISSTTRRAATTIIVVEE IINNFFOORRMMAATTIIOONN AANNDD AACCKKNNOOWWLLEEDDGGEEMMEENNTTSS


  44..11..  FFeeeeddbbaacckk

  Send your comments about this F.A.Q. to:

  Paolo Nenzi <p.nenzi@ieee.org>.

  Send your comments about ngspice to:

  Paolo Nenzi <p.nenzi@ieee.org>.


  44..22..  FFoorrmmaattss iinn wwhhiicchh tthhiiss FFAAQQ iiss aavvaaiillaabbllee

  This document is available only in ASCII format in the ngspice source
  package.


  44..33..  AAuutthhoorrsshhiipp aanndd aacckknnoowwlleeddggeemmeennttss

  Parts of the questions and answers are originate from Paolo Nenzi.


  44..44..  DDiissccllaaiimmeerr aanndd CCooppyyrriigghhtt

  This document is provided as is. The information in it is not
  warranted to be correct: you use it at your own risk.