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Cylindrical Via (Closed Form): VIA



Name Description Unit Type Default
ID Element ID Text V1
D External diameter of via (external diameter of via cylinder) Length L[1]
H Substrate thickness Length H[1]
T Thickness of metal (thickness of via cylinder wall) Length T[1]
RHO Metal bulk resistivity normalized to gold   Rho[1]
*SNAME Via drawing definition   Default

[1] User-modifiable default. Modify by editing under $DEFAULT_VALUES in the default.lpf file in the root installation directory. See the AWR Microwave Office Layout Guide for details.

* indicates a secondary parameter

Implementation Details

This model is implemented as a lumped element series inductor and resistor whose values are derived from the dimensions and resistivity of the hollow cylindrical conductor.

RHO is a ratio of actual metal bulk resistivity to gold bulk resistivity, that is, the increase in RHO results in an increase of series resistor. This model allows a perfectly conducting via at RHO=0.

Recommendations for Use

Discontinuity models function most accurately when attached to lines that match their corresponding edges. Directly connecting discontinuity models to one another reduces their accuracy.


VIA models draw according to the SNAME parameter setting on the via, as configured in the LPF. If this parameter is left blank the via definition in the LPF is used to define the via layers. See “Via Definitions” for details. This typically works well if there is only one via type in the design. If you need to have different via layers, the best approach is to create structures in the LPF for each type, then set the SNAME parameter to match the structure name in the LPF. See “Structure Type Definitions” for more information.


[1] Goldfarb M.E., Pucel R.A., "Modeling Via Hole Grounds in Microstrip" IEEE Microwave and Guided Wave Letters, Vol. 1, No.6, June 1991, pp. 135-137

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