http://www.gnucap.com/dokuwiki/ 2026-04-16T10:27:48-05:00 FeedCreator 1.7.2-ppt DokuWiki 2011-11-14T16:55:58-05:00 2011-11-14T16:55:58-05:00 2011-11-14T16:55:58-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:basic_syntax?rev=1321311358&do=diff

This page applies to the simple “Spice” basic devices, and some extended forms of them. Spice format The format for simple devices is: label (connections) value Parentheses around the connections are optional. Examples: Vin (in 0) 10 Lseries (in out) .01 Cshunt (out 0) 100u Rload (out 0) 100 The first letter of the label determines the type:

2009-07-03T14:15:43-05:00 2009-07-03T14:15:43-05:00 2009-07-03T14:15:43-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:complex?rev=1246648543&do=diff

Syntax complex ( realpart imaginarypart options ) Purpose Complex component value, using a real and imaginary part. AC only. Comments Strictly, this adds no functionality over the polar option on any function, except notational convenience. It is only meaningful in AC analysis. Others take the real part and ignore the imaginary part. No warning is issued.

2009-07-03T14:22:33-05:00 2009-07-03T14:22:33-05:00 2009-07-03T14:22:33-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:exp?rev=1246648953&do=diff

Syntax exp (args) exp (iv pv td1 tau1 td2 tau2 period) Purpose The component value is an exponential function of time. Comments For voltage and current sources, this is the same as the Spice “exp” function, with some extensions. The shape of the waveform is described by the following algorithm:

2009-07-03T16:00:36-05:00 2009-07-03T16:00:36-05:00 2009-07-03T16:00:36-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:fit?rev=1246654836&do=diff

Syntax fit x1,y1 x2,y2 ... args pwl x1,y1 x2,y2 ... args Purpose FIT fits a set of data using piecewise polynomials, or splines. PWL is a a special case of FIT, it defines a piecewise linear transfer function or time dependent value. Comments The “fit” function fits a set of piecewise polynomials to a set of data.

2015-12-11T15:39:55-05:00 2015-12-11T15:39:55-05:00 2015-12-11T15:39:55-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:generator?rev=1449869995&do=diff

Syntax generator scale Purpose The component “value” is dependent on a “signal generator”, manipulated by the “generator” command. Comments For transient analysis, the “value” is determined by a signal generator, which is considered to be external to the circuit and part of the test bench. See the “generator” command for more information.

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Basics All simple components can have a behavioral description, with syntax designed as an extension of the Spice time dependent sources. They are not necessarily physically realizable, but provide useful modeling capability. Some only work on particular types of analysis, or over a small range of values. Some can be used together, some cannot.

2015-12-11T15:39:55-05:00 2015-12-11T15:39:55-05:00 2015-12-11T15:39:55-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:poly?rev=1449869995&do=diff

Syntax poly c0 c1 c2 c3 ... poly c0 c1 c2 c3 ... args Purpose Defines a transfer function by a one dimensional polynomial. Comments For capacitors, this function defines charge as a function of voltage. For inductors, it defines flux as a function of current. If you have the coefficients defining capacitance or inductance, prepending a “0” to the list will turn it into the correct form for Gnucap.

2015-12-11T15:39:55-05:00 2015-12-11T15:39:55-05:00 2015-12-11T15:39:55-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:posy?rev=1449869995&do=diff

Syntax posy c1,p1 c2,p2 ... posy c1,p1 c2,p2 ... args Purpose Defines a transfer function by a one dimensional ``posynomial'', like a polynomial, except that the powers are arbitrary, and usually non-integer. Comments There is no corresponding capability in any SPICE that I know of.

2009-05-27T10:19:17-05:00 2009-05-27T10:19:17-05:00 2009-05-27T10:19:17-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:probes?rev=1243437557&do=diff

All basic elements Most two node elements (capacitors, inductors, resistors, sources) and four terminal elements (controlled sources) have at least the following parameters available. Others are available for some elements. Some of these probes do not work for all devices, or all analysis. It will print ”??” as the value when it doesn't work.

2009-07-03T14:12:48-05:00 2009-07-03T14:12:48-05:00 2009-07-03T14:12:48-05:00 http://www.gnucap.com/dokuwiki/doku.php/gnucap:manual:devices:basic:pulse?rev=1246648368&do=diff

Syntax pulse args pulse iv pv delay rise fall width period Purpose The component value is a pulsed function of time. Comments For voltage and current sources, this is the same as the Spice “pulse” function, with some extensions. The shape of a single pulse is described by the following algorithm:

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Syntax sffm args sffm offset amplitude carrier modindex signal Purpose The component value is a sinusoid, frequency modulated by another sinusoid. Comments For voltage and current sources, this is the same as the Spice SFFM function, with some extensions.

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Syntax sin args sin offset amplitude frequency delay damping Purpose The component value is a sinusoidal function of time, with optional exponential decay. Comments For voltage and current sources, this is the same as the Spice SIN function, with some extensions.

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Syntax tanh gain limit tanh args Purpose Defines a hyperbolic tangent, or soft limiting, transfer function. Comments There is no corresponding capability in any SPICE that I know of, but you can get close with POLY. For capacitors, this function defines charge as a function of voltage. For inductors, it defines flux as a function of current.