1NGMULTIDEC(1)               General Commands Manual              NGMULTIDEC(1)
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NAME

6       ngmultidec - make ngpice sub-circuit for coupled transmission lines
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SYNOPSIS

9       ngmultidec [ options...  ]
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DESCRIPTION

12       ngmultidec  writes  an  ngspice  input  file  to  standard output which
13       describes a sub-circuit for coupled lines using uncoupled simple  lossy
14       lines.
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16       Each  generated  subcircuit models a 4-conductor transmission line with
17       the following parameters: length l, line capacitance c, line resistance
18       r, line conductance g, inductive_coeff_of_coupling k, inter-line capac‐
19       itance cm, length l.  Derived parameters are: lm, ctot.  The values  of
20       l,  c,  the  model name, the number of conductors and the length of the
21       line must be specified.
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23       It is important to note that the model is a simplified one -  the  fol‐
24       lowing assumptions are made: 1. The self-inductance l, the self-capaci‐
25       tance ctot (note: not c), the series  resistance  r  and  the  parallel
26       capacitance  g  are the same for all lines, and 2. Each line is coupled
27       only to the two lines adjacent to it, with the same coupling parameters
28       cm  and  lm.  The first assumption implies that edge effects have to be
29       neglected.  The utility of these assumptions is that they make the sL+R
30       and sC+G matrices symmetric, tridiagonal and Toeplitz, with useful con‐
31       sequences (see the paper referenced below).
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33       It may be noted that a  symmetric  two-conductor  line  is  represented
34       accurately by this model.
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36       Standard  C  language  scientific  (exponent)  notation may be used for
37       options' numeric values.
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OPTIONS

40       -osubcircuit_name
41              Set the subcircuit name
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43       -lline_inductance
44              Set the line inductance.
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46       -cline_capacitance
47              Set the line capacitance.
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49       -rline_resistance
50              Set the line resistance.
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52       -gline_conductance
53              Set the line conductance.
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55       -kinductive_coefficient_of_coupling
56              Set the value of the inductive coefficient  of  coupling,  whose
57              absolute value k must be less than 1.0.
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59       -xline-to-line-capacitance
60              Set the line-to-line capacitance.
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62       -Llength
63              Set the length of the line.
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65       -nnumber
66              Set the number of conductors.
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68       -u     Write a usage message to standard error.
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EXAMPLE

71              ngmultidec  -n4 -l9e9 -c20e-12 -r5.3 -x5e12 -k0.7 -otest -L5.4 >
72              test.cir
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SEE ALSO

75       Efficient Transient Simulation of Lossy Interconnect,
76       J.S. Roychowdhury and D.O. Pederson,
77       Proceedings of the Design Automation Conference,
78       pp. 740-745.
79       1991.
80       http://portal.acm.org/citation.cfm?doid=127601.127762
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82       ngnutmeg(1), ngproc2mod(1), ngsconvert(1), ngspice(1), nghelp(1).
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86                                  2014-10-28                     NGMULTIDEC(1)
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