Why Setup Time Formula is like this?

[Haripal Kochhar]

Setup Time = Max Signal Delay - Minimum Clock Delay

why we reduce Minimum Clock Delay if we dnt do that even our design will be more robust. So what is the reason of reducing Minimum Clock Delay from Max Signal Delay..

 

[Prashanthanilm]

The Signal delay should be always be more than Clock period to avoid the set up violations.

 

[gasingh]

Setup Time = Max Signal Delay - Minimum Clock Delay

why we reduce Minimum Clock Delay if we dnt do that even our design will be more robust. So what is the reason of reducing Minimum Clock Delay from Max Signal Delay..

For Setup time specification to be met , data has to reach the flip flop input Ts time before Clock Arrival , If clock gets delayed by some amount ,data can also tolerate the extra delay , the worst case for setup will occur when clock is right at time ( Minimum dELAY ) and data is as late as can happen ( Maximum Delay ) , The difference of the two will be the " Guarenteed Available Setup tIME" , the Setup time is the property of the actual device(Flip Flop) , if the available Setup time is more than Setup time of the device then it will function properly

Train Analogy :
Clock = Train
Data = You
Available Setup time = Time Available to board = (Time when you Reach ) - (Time when Train Reaches)
Setup Time = Time that you require to board the train
MetaStability = When you Are just hanging from the gate and can land on either side and can take a finite amount of time to reach final state ( Struggle Time )
Metastability Resolution Time = Time that you struggled at the gate before making inside or falling outside