What is a negative slack and how it affects timing?

negative slack

wat is negative slack & how it affects timing??

wat does negative slack results??

slack = RT -AT
if AT is greater than RT then nagative slack occurs ........

i want in detail.......

thanks.

negative slack

simply put, it means that the timing constraints that you have given for your design, are not met.

in other words, either u have the option of changing(relaxing) your constraints, or come up with a better design for the same functionality to meet the existing constraints.

Re: negative slack

This simply means , that u r system is showing the setup time violations.
jus read some good stuff on sta or setup time violations . lot of good files available for STA on EDAboard

Re: negative slack

In static timing analysis, slack indicates whether timing is met along a timing path. A positive slack means that the signal can get from the startpoint to the endpoint of the timing path fast enough for the circuit to operate correctly. A negative slack means that the data signal is unable to traverse the combinational logic between the startpoint and the endpoint of the timing path fast enough to ensure
correct circuit operation.

In late mode analysis, slack is the difference between the required time and the arrival time for the timing path. The time that a signal needs to arrive at the endpoint of the path to ensure that timing is met is called the required time. The time that the signal actually arrives at the endpoint is called the arrival time.

Because slack is the required time minus the arrival time, a negative slack indicates that the signal arrives at the endpoint later than the time it needs to be there, and vice versa for positive slack.

Re: negative slack

Hi,
In negative slack condition data arrives after the sampling clock edge arrival, so, in this case one cannot able to latch the correct data. There is also posibility of going into metastability if the data arrives in setup time window.

negative slack

the negative slack has some reson , may the library is use to fix setup timing, this is a old method, now i think nobody use it. An other reason maybe the cell fanout and fanin is not match, the delay timing is calculate from fanin and fanout , so it will calculte a negative timing.