B sources (complete reference) - Revision history

Analogspiceman: /* B-sources */

2019-11-07T14:14:31Z

‎B-sources

Analogspiceman: /* B-sources */

2019-11-07T13:22:28Z

‎B-sources

Analogspiceman: /* B-sources */

2019-10-31T19:52:19Z

‎B-sources

Analogspiceman: /* B-sources */

2019-10-31T17:26:45Z

‎B-sources

Analogspiceman: /* B-sources */ Added behavior power sources and smallsig(x) function. Updated undocumented status of functions and generally updated to match Help file.

2019-10-31T06:57:54Z

‎B-sources: Added behavior power sources and smallsig(x) function. Updated undocumented status of functions and generally updated to match Help file.

Lewispaul: /* B-sources */

2016-02-23T16:30:40Z

‎B-sources

Analogspiceman: /* B-sources */

2013-05-29T14:22:13Z

‎B-sources

Lewispaul: Add DISQUS for comments

2011-09-21T00:38:09Z

Add DISQUS for comments

Analogspiceman: /* B-sources */

2011-08-08T08:01:26Z

‎B-sources

Analogspiceman at 07:18, 18 August 2009

2009-08-18T07:18:31Z

@@ Line 49: / Line 49: @@
        +   | floating point addition
   ---------+--------------------------------------------------
-  *   ==   b true if preceding expression is equal to succeeding expression, otherwise false
+  *   ==   b true if preceding expression is exactly equal to succeeding expression, otherwise false
       >=   b true if preceding expression is greater than or equal to succeeding expression, otherwise false
       <=   b true if preceding expression is less than or equal to succeeding expression, otherwise false

@@ Line 109: / Line 109: @@
         dnlim(x,y,z) | the greater of x or y with soft limit zone of z
            if(x,y,z) | if x > .5 then y else z
-   table(x,x1,y1...) | interpolate y(x) per a lookup table
+   table(x,x1,y1...) | interpolate y(x) per a lookup table of monotonic (x1<x2<x3...) x-ordered point pairs
-  or *tbl: x1<x2... |   of x-ordered point pairs
+ *  tbl(x,x1,y1...) | alternate form of table()
             uramp(x) | x if x > 0, else 0.
-      *stp(x), u(x) | unit step, 1 if x > 0, else 0
+ *     stp(x), u(x) | unit step, 1 if x > 0, else 0
               buf(x) | 1 if x > .5, else 0
   ~(x), !(x), inv(x) | 0 if x > .5, else 1

@@ Line 19: / Line 19: @@
 The first syntax specifies a behavioral voltage source and the next is a behavioral current source.&nbsp; For the current source, parallel resistance and capacitance may be specified with the '''Rpar''' and '''Cpar''' instance parameters.
-'''Tripdv''' and '''tripdt''' control step rejection.&nbsp; If the voltage across a source changes by more than '''tripdv''' volts in '''tripdt''' seconds, that simulation time step is rejected. See [[B_sources_(common_examples)]] for a case where this does not appear to apply.
+'''Tripdv''' and '''tripdt''' control step rejection.&nbsp; If the voltage across a source changes by more than '''tripdv''' volts in '''tripdt''' seconds, that simulation time step is rejected. See [[B sources (common_examples)]] for a case where this does not appear to apply.
 The Laplace transform is applied to the result of the behavioral current or voltage signal.&nbsp; The Laplace transform must be a function solely of '''s'''.&nbsp; The frequency response at frequency f is found by substituting '''s''' with sqrt(-1)*2*pi*f.&nbsp; The time domain behavior is found from the impulse response obtained from the Fourier transform of the frequency domain response.&nbsp; LTspice must guess an appropriate frequency range and resolution.&nbsp; The response must drop at high frequencies or an error is reported.&nbsp; It is recommended that the LTspice first be allowed to make a guess at this and then check the accuracy by reducing '''reltol''' and/or '''mtol''' (*default=1) or explicitly setting '''nfft''' and the '''window'''.&nbsp; The reciprocal of the value of the '''window''' is the frequency resolution.&nbsp; The value of '''nfft''' times this resolution is the highest frequency considered.&nbsp; For Laplace expressions, ^ signifies exponentiation.

@@ Line 1: / Line 1: @@
 == '''B-sources''' ==
-This is supposed to be like the corresponding Help file topic, but with more complete information.
+This reference is consistent with the Help file topic, but with friendlier presentation and more complete information.&nbsp; For examples of b-source usage see [[B sources (common examples)]].
 '''B.  Arbitrary behavioral voltage or current sources.'''

@@ Line 5: / Line 5: @@
 '''B.  Arbitrary behavioral voltage or current sources.'''
-Symbol names: BV, BI, *BR (arbitrary resistor)
+Symbol names: BV, BI, *BR (arbitrary resistor), *BP (arbitrary power sink or source)
 Syntax (* denotes undocumented features):
-     Bxxx n1 n2 V=<expression> OR I=<expression> [Rpar=<value>]
+     Bxxx n1 n2 V=<expression>
      + [[ic=<value>] tripdv=<value>] [tripdt=<value>]
      + [Laplace=<func(s)> [window=<time>] [nfft=<num>] [mtol=<num>]]
   *  + [[units] Freq=<valuelist> [delay=<value>]]
   *  + [NoJacob]
-The first syntax specifies a behavioral voltage source and the next is a behavioral current source.&nbsp; For the current source, a parallel resistance may be specified with the Rpar instance parameter.
+ *  Bxxx n1 n2 R=<expression>
-Tripdv and tripdt control step rejection.&nbsp; If the voltage across a source changes by more than tripdv volts in tripdt seconds, that simulation time step is rejected. See [[B_sources_(common_examples)]] for a case where this does not appear to apply.
+The first syntax specifies a behavioral voltage source and the next is a behavioral current source.&nbsp; For the current source, parallel resistance and capacitance may be specified with the '''Rpar''' and '''Cpar''' instance parameters.
-The Laplace transform is applied to the result of the behavioral current or voltage signal.&nbsp; The Laplace transform must be a function solely of s.&nbsp; The frequency response at frequency f is found by substituting s with sqrt(-1)*2*pi*f.&nbsp; The time domain behavior is found from the impulse response obtained from the Fourier transform of the frequency domain response.&nbsp; LTspice must guess an appropriate frequency range and resolution.&nbsp; The response must drop at high frequencies or an error is reported.&nbsp; It is recommended that the LTspice first be allowed to make a guess at this and then check the accuracy by reducing reltol and/or mtol (*default=1) or explicitly setting nfft and the window.&nbsp; The reciprocal of the value of the window is the frequency resolution.&nbsp; The value of nfft times this resolution is the highest frequency considered.&nbsp; For Laplace expressions, ^ signifies exponentiation.
+'''Tripdv''' and '''tripdt''' control step rejection.&nbsp; If the voltage across a source changes by more than '''tripdv''' volts in '''tripdt''' seconds, that simulation time step is rejected. See [[B_sources_(common_examples)]] for a case where this does not appear to apply.
-<nowiki>*</nowiki> The transfer function of the Freq circuit element is specified by an ordered list of points of freq(Hz), mag(dB) and phase(deg) as follows: <(f1,m1,p1)[(f2,m2,p2)...]> where f1<f2<f3, etc.&nbsp; The following units specifiers may optionally precede the Freq keyword: “rad”=radians, “mag”=non dB, (“dB” and “deg” return the defaults), “r_i”=real and imaginary in place of magnitude and phase.&nbsp; If a delay value is called out, the phases of the table values are modified to reflect the delay (delay is automatically adjusted to maintain causality in any case).
+The Laplace transform is applied to the result of the behavioral current or voltage signal.&nbsp; The Laplace transform must be a function solely of '''s'''.&nbsp; The frequency response at frequency f is found by substituting '''s''' with sqrt(-1)*2*pi*f.&nbsp; The time domain behavior is found from the impulse response obtained from the Fourier transform of the frequency domain response.&nbsp; LTspice must guess an appropriate frequency range and resolution.&nbsp; The response must drop at high frequencies or an error is reported.&nbsp; It is recommended that the LTspice first be allowed to make a guess at this and then check the accuracy by reducing '''reltol''' and/or '''mtol''' (*default=1) or explicitly setting '''nfft''' and the '''window'''.&nbsp; The reciprocal of the value of the '''window''' is the frequency resolution.&nbsp; The value of '''nfft''' times this resolution is the highest frequency considered.&nbsp; For Laplace expressions, ^ signifies exponentiation.
-<nowiki>*</nowiki> The NoJacob parameter unburdens a device from carrying the mathematical overhead of a Jacobian.&nbsp; For linear or certain well behaved b-source expressions, this small reduction in computational burden can reduce run times ''slightly''.&nbsp; Use with <font color="red">extreme caution</font>, as this greatly increases the risk of creating convergence problems or other errors if misapplied.
+<nowiki>*</nowiki> The transfer function of the '''Freq''' circuit element is specified by an ordered list of points of freq(Hz), mag(dB) and phase(deg) as follows: <(f1,m1,p1)[(f2,m2,p2)...]> where f1<f2<f3, etc.&nbsp; The following units specifiers may optionally precede the '''Freq''' keyword: “'''rad'''”=radians, “'''mag'''”=non dB, (“dB” and “deg” return the defaults), “'''r_i'''”=real and imaginary in place of magnitude and phase.&nbsp; If a '''delay''' value is called out, the phases of the table values are modified to reflect the '''delay''' ('''delay''' is automatically adjusted to maintain causality in any case).
 Expressions can contain the following:
 * Node voltages and differences, e.g. V(n1) and V(n1,n2).
-* Circuit element currents, e.g. I(S1), the current through switch S1 or Ib(Q1), the base current of Q1.&nbsp; However, it is assumed that the circuit element current is varying quasi-statically, that is, there is no instantaneous feedback between the current through the referenced device and the behavioral source output.&nbsp; Similarly, any ac component of such a device current is assumed to be zero in a small signal linear .ac analysis.
+* Circuit element currents, e.g. I(S1), the current through switch S1 or Ib(Q1), the base current of Q1.&nbsp; However, it is assumed that the circuit element current is varying quasi-statically, that is, there is no instantaneous feedback between the current through the referenced device and the behavioral source output.&nbsp; Similarly, any ac component of such a device current is assumed to be zero in a small signal linear .ac analysis.&nbsp; All zero impedance voltage source type elements may be used for zero delay current sensing, i.e., BV, E, H, L (with Rs=0) and V (with Rs=0)
-* The following operations, grouped in order of precedence of evaluation (* denotes undocu-mented features):
     Symbol | Operation (resultant: b= boolean; r= real part only)
@@ Line 97: / Line 106: @@
             max(x,y) | the greater of x or y
         limit(x,y,z) | intermediate value of x, y, and z, equivalent to min(max(x,y),z)
- *     uplim(x,y,z) | the lesser of x or y with soft limit zone of z
+       uplim(x,y,z) | the lesser of x or y with soft limit zone of z
- *     dnlim(x,y,z) | the greater of x or y with soft limit zone of z
+       dnlim(x,y,z) | the greater of x or y with soft limit zone of z
            if(x,y,z) | if x > .5 then y else z
    table(x,x1,y1...) | interpolate y(x) per a lookup table
@@ Line 115: / Line 124: @@
       delay(x,y[,z]) v delay of x by min(y,z) seconds
    absdelay(x,y[,z]) v delay of x by min(y,z) seconds
 {{#widget:DISQUS

← Older revision		Revision as of 00:38, 21 September 2011
Line 115:		Line 115:
	delay(x,y[,z]) v delay of x by min(y,z) seconds		delay(x,y[,z]) v delay of x by min(y,z) seconds
	absdelay(x,y[,z]) v delay of x by min(y,z) seconds		absdelay(x,y[,z]) v delay of x by min(y,z) seconds
		+
		+	{{#widget:DISQUS
		+	\|id=ltwiki
		+	\|uniqid={{PAGENAME}}
		+	\|url={{fullurl:{{PAGENAME}}}}
		+	}}

@@ Line 60: / Line 60: @@
   * echarge |  1.6021765e-19 | charge of an electron
   * kelvin  | -2.73150  e+02 | absolute zero in degrees C
 * Any user defined parameters or functions.&nbsp; Note that the parameter substitution scheme is generally symbolic, but that when curly braces are encountered, the enclosed expression is evaluated immediately.&nbsp; With functions all parameter substitution evaluation is always done before the simulation begins.&nbsp; For details, refer to the .param and the .func simulator directives defined in Help under the subchapter on Dot Commands.
@@ Line 96: / Line 97: @@
             max(x,y) | the greater of x or y
         limit(x,y,z) | equivalent to min(max(x,y),z)
            if(x,y,z) | if x > .5 then y else z
    table(x,x1,y1...) | interpolate y(x) per a lookup table