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RLGC Transmitting Line (Closed Form): RLGC_Tx

Symbol

Summary

RLGC_Tx provides computation of circuit parameters for general transmission lines whose behavior in the frequency domain is governed by a user-supplied table of primary per-unit-length line parameters R, L, G, and C.

Equivalent Circuit

Parameters

Name Description Unit Type Default
ID Name Text TL1
Len Length of Line Length L[1]
F Vector of Frequencies at which L, C, R, G specified Frequency 1 GHz
R Vector of Series R per-unit-length Resistance/meter 100
L Vector of Series L per-unit-length Inductance/meter Li[1]
G Vector of Shunt G per-unit-length Conductance/meter 0
C Vector of Shunt C per-unit-length Capacitance/meter C[1]

[1] User-modifiable default. Modify by editing the DEFAULT.LPF file in the root installation directory. See the “Default Values” for details.

Parameter Details

F. Vector of frequencies at which R, L, G, and C parameters are specified. Frequencies must be sequential and specified in ascending order.

R. Vector of series resistance (see Equivalent Circuit) per-unit-length specified in resistance project units per meter. Each vector entry must be specified at the corresponding frequency entry from frequency vector >F.

L. Vector of series inductance (see Equivalent Circuit) per-unit-length specified in inductance project units per meter. Each vector entry must be specified at the corresponding frequency entry from frequency vector F.

G. Vector of shunt conductance (see Equivalent Circuit) per-unit-length specified in conductance project units per meter. Each vector entry must be specified at the corresponding frequency entry from frequency vector F.

C. Vector of shunt capacitance (see Equivalent Circuit) per-unit-length specified in capacitance project units per meter. Each vector entry must be specified at the corresponding frequency entry from frequency vector F.

Parameter Restrictions and Recommendations

  1. Size of vector parameters R, L, G, and C must be exactly equal to the size of frequency vector F.

  2. If project evaluation frequency is out of range of frequencies in F then R, L, G, and C parameters are extrapolated as constant values equal to the first/last entries of corresponding vectors. No warning is issued.

  3. Vector can be specified in three ways: First, it can be entered as a right side value of model parameter, e.g. R={100,102,110,113,120}; Second, vector can be specified elsewhere in equation; Third way is specification of vector in a column or row of a text file; Third way provides a convenient and flexible method of specification of all RLGC parameters in the single location. Just create for example file RLGC.txt containing space separated columns of R1, R2 etc. First column must represent frequency in project units (note that changing of project default frequency units will demand manual scaling of frequencies in this file). Import or link this file to your project and give it a name, say, RLGC_15. Now you can specify, say, parameter R as R = Col(datafile("RLGC_15"),2). This means that values of vector R will be copied to the model from the column 2 of file RLGC.txt imported under name RLGC_15. If you prefer to deploy your data row-wise use R = Row(datafile("RLGC_15"),2).

  4. If your project uses text file input to feed data to this model be aware what frequency, resistance, inductance or conductance units this file implies. There is a chance that default units of your project differ from those in your data file. If this happens, you must scale input values multiplying call of function Col or Row by scaling coefficient. For example, if your project uses capacitances in picofarads and data file contains data in Farads you may get capacitance data from the column 5 of data file RLGC_15 like this: C1= 1e+12*Col(datafile("RLGC_15"),5).

Implementation Details

Model implementation is based on linear interpolation of RLGC parameters at each project evaluation frequency. Interpolation uses lookup tables user-supplied via parameters. If project evaluation frequency is out of range of frequencies in F then R, L, G, and C parameters are extrapolated as constant values equal to the first/last entries of corresponding vectors.

Layout

This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

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