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Diff class clearance

autodeskguest

Are there any plans to split the diff routing clearance from the diff

spacing/gap? When you route diff signals now, the class clearance gets

used for spacing/gap too.

 

A typical example

spacing/gap (air between diff pair):0.1mm

track width:0.1mm

wanted clearance (to neighbour tracks): usually a few multiples of the

track width.

 

This forces me to change all clearances during DRC, and back again when

I want to route.

 

Of course there are more issues with diff routing, but lets do one step

at a time.

 

Parents

  • You can set that in the netclass editor. Click on the ">>" button to open

    the netclass matrix editor where

    you can set the clearance in respect to other netclasses.

     

    What annoys me is that within a class, you can't set the clearance and

    trackwidth depending to the layer.

    The impedance of a track depends on the distance to a groundlayer and,

    depending to the board buildup,

    the distance between the different layers varies.

    So, it would be very convenient if, during routing of a differential pair

    (USB, LVDS), when changing layer,

    the width and clearance changes automatically in order to maintain the

    correct impedance.

     

    --

    http://www.eaglecentral.ca :: The original and best browser access to CadSoft EAGLE support forums.  Supported by EAGLE licenses purchased through us :: http://www.eaglelicenses.com

     

  • in reply to Joop14

    On 07.12.2016 22:13, Joop wrote:

    You can set that in the netclass editor. Click on the ">>" button to open

    the netclass matrix editor where

    you can set the clearance in respect to other netclasses.

     

    I think you misunderstood. The clearance in the netclasses does both

    work as gap (for diff pairs) AND clearance to other classes. They need

    to be split.

     

    What annoys me is that within a class, you can't set the clearance and

    trackwidth depending to the layer.

    The impedance of a track depends on the distance to a groundlayer and,

    depending to the board buildup,

    the distance between the different layers varies.

    So, it would be very convenient if, during routing of a differential pair

    (USB, LVDS), when changing layer,

    the width and clearance changes automatically in order to maintain the

    correct impedance.

     

    I agree this is also something to improve. For now I have made a script

    to change widths of a certain class on certain layers based on a stackup

    agreed upon with the manufacturer, but it would be nice if the width

    (and diff gap) were automatically changed when a stackup was changed.

    The DRC stackup definition is basically just missing the substrate

    dielectric (Er) constant fields to calculate this.

     

     

  • in reply to autodeskguest

    Morten Leikvoll wrote on Thu, 08 December 2016 09:38

    On 07.12.2016 22:13, Joop wrote:

    You can set that in the netclass editor. Click on the ">>" button

    to open

    the netclass matrix editor where

    you can set the clearance in respect to other netclasses.

     

    I think you misunderstood. The clearance in the netclasses does both

    work as gap (for diff pairs) AND clearance to other classes. They need

     

    to be split.

     

     

    You are right. My mistake.

    Let's hope they give this priority over implementing online/webbased

    services for hobbyists...

     

    --

    http://www.eaglecentral.ca :: The original and best browser access to CadSoft EAGLE support forums.  Supported by EAGLE licenses purchased through us :: http://www.eaglelicenses.com

     

Reply
  • in reply to autodeskguest

    Morten Leikvoll wrote on Thu, 08 December 2016 09:38

    On 07.12.2016 22:13, Joop wrote:

    You can set that in the netclass editor. Click on the ">>" button

    to open

    the netclass matrix editor where

    you can set the clearance in respect to other netclasses.

     

    I think you misunderstood. The clearance in the netclasses does both

    work as gap (for diff pairs) AND clearance to other classes. They need

     

    to be split.

     

     

    You are right. My mistake.

    Let's hope they give this priority over implementing online/webbased

    services for hobbyists...

     

    --

    http://www.eaglecentral.ca :: The original and best browser access to CadSoft EAGLE support forums.  Supported by EAGLE licenses purchased through us :: http://www.eaglelicenses.com

     

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