Layout Driven Design

Discussion created by Jerry_Suiter on Oct 22, 2008
Latest reply on Apr 19, 2011 by Vern_Wnek



I would like to have a community discussion on Layout Driven Design (LDD) to understand what type of features are most used or would be used.  First of all, let me describe some basic LDD use cases for users who may not have been exposed to this functionality.



LDD allows a PCB user to make changes within layout that normally are schematic driven.  Here are some typical use cases that I have seen requests for:


  • Test Points - Ability to place testpoints in layout and have these sent back to the schematic as test point symbols.

  • Change Part Number - Ability to change the part number within layout and send this update back to the schematic. Typically could be used for discreet devices in order to adjust values.

  • Add Part - Ability to instantiate a part within layout and send this part back to the schematic. Typically used to add discreet pull-up/down resistors or decupling capacitors.


There are many other use cases supporting LDD with the most feature rich used for prototyping boards where the board is laid out without a schematic and all parts and nets are instantiated from scratch.  At some point the user can drive the layout into a schematic and generate the necessary connectivity and symbols to represent the layout design. 


  • Based on this, how many users are interested in basic LDD functionality as I described with the 3 use cases above?

  • What about more advanced capabilities like the ability to layout full prototype designs without a schematic?

  • Lastly, when PCB user is making changes that require instantiation of schematic circuitry, would you expect this to be allowed concurrently while schematic changes are being made or have this as a more controlled situation to ensure conflicts between schematic and layout changes do not conflict?





Jerry Suiter

ExpeditionPCB/XtremePCB Product Marketing Manager