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Single Conductor Stripline (Closed Form): SLIN

Symbol

Topology

Parameters

Name Description Unit Type Default
ID Element ID Text SL1
W Conductor width Length W[1]
L Conductor length Length L[1]
SSUB 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 SSUB is present in the schematic, this substrate is automatically used. If multiple SSUB substrate definitions are present, the user must specify.

Implementation Details

This circuit component models a length of Stripline Transmission Line. The model assumes a TEM (Transverse Electric Magnetic) mode of propagation and incorporates the effects of dielectric and conductive losses. The parameters W (Strip Width) and L (Strip Length) are lengths entered in the default length units. The parameter SSUB specifies the Stripline Substrate element, which defines additional cross sectional parameters of the transmission line. This model also warns of the possibility of higher order propagating modes if they exist.

Circuit Model Synthesis

SLIN 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.

Restrictions

Zo>94.25/(εr)1/2 (for T≠0) with Zo= Characteristic Impedance of Trans Line.

T/B≤0.1 Recommended

Rho≤100 Recommended

NOTE: SCLIN implies that parameter Rho specified on substrate definition SSUB represents bulk resistance of conductor metal normalized to copper. This normalization is specific to SCLIN (and SLIN as well); other transmission line models use Rho normalized to gold. So, if one obtained value of Rho normalized to gold ( ρnorm to gold ) than Rho normalized to copper ( ρnorm to copper ) can be evaluated as ρnorm to copper=1.4353ρnorm to gold

References

[1] H.A. Wheeler, "Transmission-Line Properties of a Strip Line Between Parallel Planes", IEEE Trans on Microwave Theory and Techniques, Vol. MTT-26, No. 11, November 1978 p.866-876

[2] S.B. Cohn, "Characteristic Impedance of the Shielded-Strip Transmission Line", IRE Transactions MTT, July 1954 p. 52-55

[3] H.A. Wheeler, "Formulas for the Skin Effect", Proceedings of the IRE September, 1942 p.412-424

[4] K.C. Gupta "Computer-Aided Design of Microwave Circuits", Artech House1981 p.60

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