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Slow lib for setup and fast lib for hold check.!

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yadavvlsi

yadavvlsi

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We use slow libraries for setup time and fast libraries for hold time voilation check. Why it os so?
 

yadavvlsi said:
We use slow libraries for setup time and fast libraries for hold time voilation check. Why it os so?
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SETUP:
flop_launch_clk_edge->combo_logic_delay->flop_capture_clk_edge. Setup is defined as the amount of time required for the signal to be valid before the capture clock edge. This is effected by delay of the source flop and combo logic. If the signal is too close to the capture clock edge (I.e lots of delay) then it will violate setup time. max delay / slow libraries are needed to verify this path

HOLD:
When the source flop launches a signal the previous state must be maintained for the specified hold time before the signal transitions to it's new value.
Fast libraries are need to verify that at the flops fastest operation there will be a minimum hold time value held before the signal transitions to it's new state.
 
Because setup violation happens in the path with maximum delay and hold in the path with minimum delay. So we take worst case and the best case to fix both..
 

correct as jeevan said
jeevan.life said:
Because setup violation happens in the path with maximum delay and hold in the path with minimum delay. So we take worst case and the best case to fix both..
Click to expand...
 

In OCV(On-Chip Variation) mode, setup check uses the timing delay values from the Max library group for the data and the launch clock network delay. And uses the delay values from the Min library group for the capturing clock network delay assuming that the clocks are set in propagated mode.
 

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