Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Can't understand the Tsu and Th defination in Quartus

Tsu=data delay-clock delay+uTsu; Th=clock delay-data delay +uTh; Take the defination of Tsu for example, we can get that longer the data delay, longer the Tsu, which is not understandable. The o...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Are you using Classic TAN or TimeQuest?

The micro parameters are fixed values. Just consider them delays for all intents and purposes. I didn't follow everything, but you state that the longer the data delay the longer the Tsu, which is not understandable. That is correct. Let's pretend the data delay is 6ns and the clock delay is 1ns(ignore everything else for now). In order for your data to get to the register before the clock, you need to have it at the device input 5ns before the clock is at the device input. If you don't, you will violate this Tsu requirement of 5ns. So the larger the data delay, the larger the Tsu requirement. Does that make sense?