Go to www.awrcorp.com
Back to search page Click to download printable version of this guide.

Stripline (EM Quasi-Static): S1LIN

Symbol

Summary

S1LIN models a section of single stripline. The model allows thickness and properties of dielectrics at both sides of a strip to be different.

Topology

Parameters

Name Description Unit Type Default
ID Name Text TL1
W Conductor width Length W[1]
L Conductor length Length L[1]
Acc Accuracy parameter   1
SSUBL Substrate definition Text 3[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 SSUBL is present in the schematic, this substrate is automatically used. If multiple SSUBL substrate definitions are present, you must specify which to use.

Parameter Details

SSUBL. Two-layer substrate parameters (H1, H2, Er1, Tand1, Er2, Tand2) are listed in the SSUBL model description. The substrate is comprised of the layered substrate itself, metallic cover, and backing ground plane.

Acc. The accuracy parameter. The default value for Acc is 1. If Acc is less than 1 or greater than 10 it is set automatically to 2.

Parameter Restrictions and Recommendations

  1. Accuracy parameter A is limited to 1≤Acc≤10 . A larger value of Acc increases the density of mesh used in computations. The accuracy of model parameters may gain slightly from increasing Acc at the expense of a noticeable growth in computation time. Generally, a good trade-off between accuracy and computation time is to set Acc to 1.

  2. This model does not impose restrictions on the conductor thickness T: thickness may be zero, positive, or negative. However, the model checks if |T|<0.95H, where H=H1 if T>0 or H=H2 if T<0 (see Topology). A negative thickness means that the conductor is recessed into the bottom dielectric layer.

Implementation Details

Model implementation is based on EM Quasi-Static technique described in [1]. It accounts for losses in metal and in substrate dielectric. Dispersion is partly included.

Circuit Model Synthesis

S1LIN supports synthesis of physical parameters based on electrical specifications using the Transmission Line Calculator. To open the Transmission Line Calculator, right-click a transmission line element in a schematic and choose Synthesize.

To perform transmission line synthesis:

  1. In the Electrical property grid, select Target check boxes for desired electrical parameters and enter a corresponding value.

  2. In the Physical property grid, update frequency and substrate parameters if needed, then select Synthesize check boxes for transmission line physical parameters to synthesize based on the targets.

  3. Click the Synthesize left arrow to run the synthesis program. The values in both property grids update with the synthesized results. An analysis is also performed with the final physical values. If synthesis cannot achieve the target values, it shows how close it came.

  4. Click OK to update the selected transmission line element with the synthesized physical parameters. Expressions are overwritten with the new, evaluated values. You can click the Undo button on the program toolbar to revert all parameters in the schematic document to their pre-synthesized state. Parameters from substrate elements are never updated since typically substrate elements are used by more than one transmission line element. Click Cancel to close the dialog box without setting the parameters into the element.

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.

Recommendations for Use

NOTE: The implementation of EM Quasi-Static models relies heavily on the involved numerical algorithms. This may lead to a noticeable increase in simulation time for schematics that employ many such models.

If the thickness of any layer is too small compared to the thickness of another layer, simulation time may also noticeably grow.

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.

Legal and Trademark Notice