setup time +ve or -ve?

[shiv_emf]

In Hold violation checking,
>report_timing -delay min

data required time is -ve (which is hold time)

> report_timing

here data required time is also -ve (which setup time ...)
why it is giving -ve for both hold n setup??

n I hav another doubt ..
what is Library setup time??
setup time for Flipflop ws changing in DC for different paths)

is it possible to hav multiplge Setup time for FlipFlop?


thanq

 

[alpeshchokshi]

Negative setup time can be there,,,,
but i have a doubt about negative holdtime?????

 

[vlsi_whiz]

The Setup and hold times for gates or logic should always be positive.

Positive setup and hold times indicate that there is enough time for the data to be stable before the arrival of the clock and also that the data will be stable for long enough.

If you get negative setup/hold times (slack) it means that ur design has a high probability of setup and hold violations. Check the failing paths (paths with -ve slack) and see if you can somehow reduce this -ve slack and make it +ve.

 

[shiv_emf]

Negative setup time can be there,,,,
but i have a doubt about negative holdtime?????

plz check slow.lib labrary...
hold times r -ve !!

Added after 1 minutes:

The Setup and hold times for gates or logic should always be positive.

Positive setup and hold times indicate that there is enough time for the data to be stable before the arrival of the clock and also that the data will be stable for long enough.

If you get negative setup/hold times (slack) it means that ur design has a high probability of setup and hold violations. Check the failing paths (paths with -ve slack) and see if you can somehow reduce this -ve slack and make it +ve.

I understand this concept of -ve or +ve slack

my question is related to -ve n +ve setup n holdtime

thanks for reply
Shiv


no reply ?

 

[qureshi]

Hi, Man


The concept about Holding time, setup time, rising time, delay time and propagation time all are defined very well in Digital Design Fundamental of Tocci.

If plz anyone have this book so plz upload it

Thanks

 

[shiv_emf]

thanks ..
How to understand .......-ve hold time

 

[vinod488]

hi,

Go to vlsibank.com/forum here -ve setup and -ve hold time are clearly explained