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Coplanar Open, with Ground Not Connected (Closed Form): CPWOC

Symbol

Topology

Parameters

CPWOC$ 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]
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, you must specify which to use.

Implementation Details

This circuit component models an open circuit termination of the coplanar waveguide. Model doesn't account for substrate thickness or presence of metallic cover or backing ground. The parameters W (strip width) and S (S - spacing between strip and the left/right ground half-plane) are dimensions entered in the default length units. This model uses equivalent coaxial waveguide prototype for evaluation open end effect. 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 parameters CPW_SUB, that are Hcover, Cover, and Gnd, are not used by this component. Conductor thickness is assumed zero.

The component doesn't account for losses in metal and in substrate dielectric. Dispersion is not included.

NOTE:

(Regarding layout cell) The CPWOC layout cell has three layout parameters (Lw1, Lw2, and L). If a one-layer line type with negative/zero offset is used to draw this layout cell, the shape drawn depends exclusively on these layout parameters and does not depend on element parameters W and S. These parameters allow you to draw a rectangle of arbitrary size on a negative layer and arrange this rectangle asymmetrically regarding the CPW waveguide. The rectangle has the dimensions (Lw1+Lw2) x L where Lw1+Lw2 is height and L is width. This rectangle provides protected space around the CPW open end.

If a multilayer line type (like plated metal line) is used and all layer offsets are either negative or zero, then the drawing is also defined by layout parameters only and does not depend on parameters W and S.

However, if some/all layer offset(s) is positive, then an additional rectangle is drawn on the negative layer(s). The dimensions of this rectangle depend of CPWOC parameters W and S.

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] N. Marcuvitz, "Waveguide Handbook", Peter Peregrinus Ltd., 1993 pp.213-216 (section 4-16)

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