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Questions Regarding Allegro cross section

Khurram

Hello all,

 

I have few questions regarding impedance calculation of transmission line calculator, cross section of ALLEGRO 16.2 and Polar.

 

Can any body tell how I can set the angle of trapezoidal trace in ALLEGRO 16.2, In 15.7 there was a option of setting it from user preferences >> signal analysis >> trapezoidal_angle_in_degrees.

 

How I can set the values of Conductive Layer Dielectric in ALLEGRO 16.2, in 15.7 this feature was present.

 

Also I find the difference in calculation of impedance between allegro field solver and cross section, any ideas how these calculations are different from each other. What values of dielectric constant should be set for copper in Allegro cross section. It seems that it is the causing difference.

 

From where I can calculate edge coupled traces present on asymmetrical strip line structure (offset strip line).

 

Actually I was using POLAR for evaluating trace width for particular impedance but now I am instructed to use cadence tool for this, but I didn’t get the same calculations from both tool there is always slight difference between them. If anybody has idea then let me know.

 

Thanks

Khurram

 

  • Khurram
    Well I got the answer of setting up the angles of trapezoidal trace, this feature is updated in ALLEGRO 16.2 and it comes with Enhanced Etch Factor SupportSomeone has any ideas regarding other questions???????

     

  • redwire

     Edge coupled asym stripline is also calculated through the cross section tool. Be sure to click on "show diff impedance" to see it.

    The diel constant of the "signal" is only intended to show the local dielectric constant around the trace.  Don't expect accuracy here when you don't know the actual resin or weave type being used for the glass.  Early Polar calcs did not include this.   Also pressing thickness varies by fabricator.

     If you're within a couple of ohms you'll be fine -- have the fabricator do the final analysis before releasing the artwork.

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