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Forums > Digital IC > Floorplanning, Place and route

Subject: RC extraction mode for postRoute timing analysis
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clsantos
Posts: 31
Online: User is Offline
6/18/2007 1:01 PM   
Hello,

I am using SOC62 and the problem is that I want to consider coupling
capacitances (not xtalk effects) during "timeDesign -postRoute", but the RC
extraction automatically performed by timeDesign
does not consider these capacitances.

1) How to force timeDesign to consider what is set by setExtractRCMode?


I tried the following commands:
######
setExtractRCMode -detail -noReduce -coupled -noise
extractRC
timeDesign -postRoute -reportOnly
timeDesign -postRoute -hold -reportOnly
######

But I'm not sure if using this option
(-reportOnly) timeDesign performs
delay calculation before timing analysis or if it
uses previous calculated timing data.

2) How to consider coupling capacitances, not crosstalking effects, during
timeDesign -postRoute (considering native extraction)?

Regards,
Cristiano.
lisiang
Moderator
Posts: 48
Online: User is Offline
6/19/2007 4:32 PM  
just make sure you have "setRCFactor -xcap ###".  You can play around with the number to see the effect on your timing.  You could use the spef from extractRC within SOC and the spef from you signoff tool and input both spefs into "ostrich" to get ###.

li siang
clsantos
Posts: 31
Online: User is Offline
6/20/2007 6:24 AM  
Thanks lisiang,

The fact is that command "timeDesign -postRoute" automatically set "setExtractRCMode -declouped" before running RC extraction and delay calculation.
I did some tests and I think the only way to avoid it is running "timeDesign -postRoute -reportOnly" after extract coupling caps.

Cristiano.
lisiang
Moderator
Posts: 48
Online: User is Offline
6/20/2007 11:20 PM  
i am suprised that the -xcap will not have effect on time using just "timeDesign". Even with the -decoupled, the extraction should still calculate the xcap and then add it to the total gnd cap. Did you try different xcap value and check to see if it produce the same/different timing?

li siang
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Forums > Digital IC > Floorplanning, Place and route > RC extraction mode for postRoute timing analysis


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