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Problems Using relative propagation delay.

Lennie

I have been spending a lot of time using Constraint manager and relative propagation delay and I an finding lots of thing that do not seen to work correctly or are what I would consider bugs. Anyone else experience this ?

I have a set of diff pairs with parallel resistors and a parallel resistor with a series cap on each leg.

For example.

1. The display comes up with different information each time I open the constraint manager. usually  Analyze updates the screen correctly.

2. Undo closes constraint manager.

3. Sometimes I have to go to analyze mode and toggle the electrical options drc unrouted in order to get the display to update . Analyze does not seem to work all the time.

4. I realized the I have to preset the pin pairs to get the lengths correct. If you goof one up you have to delete the matched group and start over. Cannot just change a pin pair.

5. The pin pair with the resistor and cap I set to IC to CAP pin pair and its always changes it to IC - resistor with I create the Matched group.

There are many other problems I see. Does anyone have all these problems ? 

  • steve
    Firstly check to make sure you are running the latest hotfix then if you are still having issues after that I would send your design into Cadence support / Channel Partner for them to review. You should be able to add / remove members of a match group without issue. For the last item check to make sure that the Class is set correctly in the schematic, if it's not - every time you import the netlist it will overwrite the pcb value with the schematic value.
  • Lennie

    Yes I am running the latest Hotfix. Its not add remove members it is changing the pin pair it is using for the current net. I do not have the net group in the schematic and did not reload it.

    I am working with Cadence but was curious if anyone had these problems.

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