CPW - Polygon's Arc Approximation

The arc approximation for polygons needs to be considered when creating Coplanar Waveguide controlled impedance traces (CPW).

click on images to view

The default Arc Approximation for Polygons is 0.5mil.


Example: The rules call for clearance of 13.6 mils



click on images to view (Gap = Pitch minus Width) = 13.6mils

The measured gap > Report > Measure Primitives

14,7 mils ?

Solution:

Reduce the Arc Approximation for the polygons poured adjacent to the CPW traces.

Re-pour the polygons and measure again.

Result 13.601mils.

Much better !