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ASIC DC Synthesis Warning

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sudhasa

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Here is the flow which we are using :

We are using memories in our design. We have generated memories using Memory compiler and then converted .lib files to .db using readlib & writelib commands.

Memory compiler generates following four files for Memory files:

1. Memory_gen_ff_1.1_-40.0_syn.lib
2. Memory_gen_ff_1.1_125.0_syn.lib
3. Memory_gen_tt_1.0_25.0_syn.lib
4. Memory_gen_ss_0.9_125.0_syn.lib

Further to generate the .db files we are using "Memory_gen_ff_1.1_-40.0_syn.lib".

We are using fast.db for our ASIC. When we are running integrated top (with memory .db files), we are getting warning as below,

##
Warning: The trip points for the library named USERLIB differ from those in the library named fast. (TIM-164) ##

Looks we are missing something in flow while generating/integrating memory files with our RTL.
 

lostinxlation

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It's just a tripping point of memory and std lib is different.
man page will give you more details on the warning.
 

skal81

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Depending on the condition used during characterization, libraries are sometimes defined with different trip points.
Old libraries are often using 10%-90% as trip points with a derate of 1, meaning that the timing values given are for a 10-90% ramp. Recent libraries often use 30%-70%, with a derate of 0.5. It means the timing is given for 30-70%, but extrapolated (the derate part).
Check the value of your libraries to be sure there is no problem. If you have 10%-90%, derate=1 and 30%-70%, derate=0.5 there should be no problem at timing analysis (in that case you can discard the warning). If it's different, you need to check the compatibility for timing analysis.
 
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