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maximum net length getNetWireLength vs reportLengthViolation

chris06

Hello,

I have a question regarding maximum net length reported by EDI.

When I use "getNetWireLength" the net length reported is the full length of the net (the sum of the length of the different pieces of metals of this net).

When I use "reportLengthViolation", the net length reported is the worst length between a driver and the farthest of its loads. For example if driver-D1 drives 2 loads load-L1 and load-L2, the tool will report the worst length between D1->L1 and D1->L2 but not the full length of the net as done by "getNetWireLength".

When a foundry gives a maximum net-length rule for a specific technology (for example 200um with TSMC28), what value do I have to consider? the one reported by getNetWireLength or the one reported by reportLengthViolation?

Thanks in advance for your help

Best Regards

Chris 

Parents
  • Chris:
    From my perspective, max length repeater insertion is an automated long net signal integrity crosstalk prevention trick.
    The transition edge is always kept relatively sharp so the victim nets are rarely too weak to be adversely effected.
    Interconnect R/C/L time constant will eventually kill any waveform edge, no matter how strong of a driver cell you use.

    reportLengthViolation / point to point, driver to sink distance is the criteria you are trying to measure.

    Shawn
Reply
  • Chris:
    From my perspective, max length repeater insertion is an automated long net signal integrity crosstalk prevention trick.
    The transition edge is always kept relatively sharp so the victim nets are rarely too weak to be adversely effected.
    Interconnect R/C/L time constant will eventually kill any waveform edge, no matter how strong of a driver cell you use.

    reportLengthViolation / point to point, driver to sink distance is the criteria you are trying to measure.

    Shawn
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