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Embedded Stripline: SEMLIN

Symbol

Topology

Parameters

Name Description Unit Type Default
ID Element ID Text TL1
W Conductor width Length W[1]
L Conductor length Length L[1]
Acc Accuracy parameter   1
SSUB4 Substrate definition Text [2]

[1] User-modifiable default. Modify by editing under $DEFAULT_VALUES in the default.lpf file in the root installation directory.

[2] If only one SSUB4 is present in the schematic, this substrate is automatically used. If multiple SSUB4 substrate definitions are present, the user must specify.

Implementation Details

This circuit component models a section of single stripline embedded into four layered substrate. Metallic cover is present on top of layer 1.

The parameters W (strip widths) and L (line length) are dimensions entered in the default length units.

The parameter Acc is the accuracy parameter (1<=Acc<=10). The default value for Acc is 1. If Acc is less than 1 or greater than 10 it is sets automatically to 2. Larger value of Acc increase density of mesh used in computations. Accuracy of model parameters may gain slightly from increasing Acc at the expense of noticeable growth of computation time. As a rule of thumb, good trade-off between accuracy and computation time is to set Acc to 1.

The parameter SSUB4 specifies the four-layer stripline substrate element, which defines additional cross sectional parameters of the transmission line. If blank, a default is used. Conductor is implied to reside on the boundary between layer 2 and layer 3.

This component doesn't impose restrictions on the conductor thickness (thickness may be zero, positive, or negative). Negative thickness means that the conductor is recessed into the layer 3.

SEMLIN may be used to implement offset (off-center) and suspended striplines simply by selecting relevant dielectric constants and thicknesses. It also can be used for implementation of covered microstrip line.

The component accounts for losses in metal and in substrate dielectric. Dispersion is not included.

NOTE: Making the thickness of any layer too small in comparison with other layers can increase the calculation time.

WARNING: The implementation of EM Quasi-Static models relies heavily on the involved numerical algorithms. This may lead to the noticeable increase of computation time for some schematics that employ many models of this kind.

Layout

This element uses line types to determine its layout. By default, the layout uses the first line type defined in your Layout Process File (LPF). You can change the element to use any of the line types configured in your process:

  1. Select the item in the layout.

  2. Right-click and choose Shape Properties to display the Cell Options dialog box.

  3. Click the Layout tab and select a Line Type.

  4. Click OK to use the new line type in the layout.

See “Cell Options Dialog Box: Layout Tab ” for Cell Options dialog box Layout tab details.

See “The Layout Process File (LPF)” for more information on editing Layout Process Files (LPFs) and to learn about adding or editing line types.

References

[1] M.B. Bazdar, A.R. Djordjevic, R.F. Harrington, and T.K. Sarkar, "Evaluation of quasi-static matrix parameters for multiconductor transmission lines using Galerkin's method," IEEE Trans. Microwave Theory Tech., vol. MTT-42, July 1994, pp. 1223-1228.

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