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About allegro PCB impedance workflow manager vision

ichliebedich over 4 years ago

Hi All!

I have curious of these things below

I set the impedance value like this (about 90 ohm) with CM Rule

but, when I ran the Analysis Workflow to see the impedance with vision

despite real impedance value is about 90ohm,the maximum calculated vision value was 53.64ohm incorrectly

Do I need to set something else?

regards.

oldmouldy over 4 years ago

The Parasitics report assumes ideal planes; the Impedance Workflow uses the Sigrity based field solvers and handles non-ideal planes; you appear to have trace segments crossing voids in the plane Shapes so there won't be "a" value for the trace impedance.
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redwire over 4 years ago

The 90 ohms comes from a differential "odd mode" impedance. Single-ended uncoupled impedance would be 45 ohms each. The differential pair will double the value. I suspect you have a diff pair and each should be 45 ohms which is what is showing in the tool.
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