Can anyone explain why are setup & hold of half cycle ssb are both freq dependent

[preethi19]

In full cycle paths setup is freq dependent while hold is not. But why in half cycle ssb paths setup and hold are both freq dependent?

 

[ThisIsNotSam]

Re: Can anyone explain why are setup & hold of half cycle ssb are both freq dependent

In full cycle paths setup is freq dependent while hold is not. But why in half cycle ssb paths setup and hold are both freq dependent?

Your terminology is confusing. What is a half cycle? Same clocks, different clocks?

Hold is also frequency dependent because no clock is perfect, and the clock uncertainty varies with frequency. Most people don't realize this.

 

[morris_mano]

Re: Can anyone explain why are setup & hold of half cycle ssb are both freq dependent

In full cycle path with the same clock, hold checks for flop to flop path, are not frequency dependent because hold checks are calculated at the same clock edge for the launching and capturing flop. Whereas, in half cycle path with the same clock, hold checks for flop to flop path are checked from either rising edge to falling edge (or falling edge to rising edge ). Based on the frequency of the clock ( assuming 50% duty cycle) , if frequency changes, hold check timing will change.