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Coplanar Open, with Ground Connected (Closed Form): CPWEG

Symbol

Topology

Parameters

CPWEG$ is a Co-Planar iCell. See the AWR Microwave Office Layout Guide for more information.

Name Description Unit Type Default
ID Element ID Text CP1
W Conductor width Length W[1]
S Gap width Length W[1]
G Gap width from TxLine end Length W[1]
CPW_SUB 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 CPW_SUB is present in the schematic, this substrate is automatically used. If multiple CPW_SUB substrate definitions are present, the user must specify.

Implementation Details

This circuit component models a gap termination of a strip of coplanar waveguide. The model does not account for substrate thickness or presence of metallic cover or backing ground. The parameters W (strip width), S (S - spacing between strip and the left/right ground halfplane) and G (gap length) are dimensions entered in the default length units. The parameter CPW_SUB specifies the substrate element, which defines additional cross-sectional parameters of the transmission line. If blank, a default is used. Some CPW_SUB parameters (Hcover, Cover, and Gnd) are not used by this component. Conductor thickness is assumed zero.

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

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.

CPW elements have special configurations for the defined line types. The center conductor geometry draws on all the layers defined in the line type. The spacing to the ground plane is then drawn on negative layers with the same name as all of the layers in the line type. You must then draw the same layers on the positive layer to complete CPW layout. See “Negative Layers ” for more information on setting up processes for positive and negative layers.

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-H. Mao, R-B.Wu, C-H Chen et al, "Characterization of coplanar waveguide open end capacitance - theory and experiment." IEEE Trans. on MTT, v. 42, No.6, June 1994, pp. 1016-1024.

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