critical path,multicycle path and false path?

false path tutorial

Hi,everybody.Can any one explain the concept of critical path,multicycle path,false path ,and the differences? thanks!best regard.

critical path + false path]

the critical path is the path witch limits your current design speed "the combinatorial path".
A multicycle path is specific path that is not critical if the signal would take more than one clock cycle i.e you don't have to service it the next clock cycle so the it might take more combinatorial logic than required by other logic in the design i.e. you don't care if this signal is acknowledged the next clock cycle it is asserted "it may take N cycles" i.e. MULTICYCLE.
a false path is more like the multicycle path but you don't ever care when would it settle down, however the false path is usually at two clock domains crossing logic. In such situation you must make extensive time anaylsis and take caution as well to avoid metastability and to make your design behave as it should

tutorial on false path

critcal path are those path has least timing margin;

false path are those path whose timing are unrelevant;

multicycle path are those path that need multiple clock cycle to complete

a mission.

best regards

Wowee said:

Hi,everybody.Can any one explain the concept of critical path,multicycle path,false path ,and the differences? thanks!best regard.

Click to expand...

false path critical path multicycle path

critical path matchs to the longest delay, it makes a decision on your system clock. multicycle path is used to loose your constraints ,to save area and get higher speed.

false path multi-cycle path

Critical path limits the ckt speed. More the delay in the critical path slower w'd be the ckt.
Multicycle path : you can specify any path as multicycle path if it can not produce results in one clock cycle. This is used to loosen you constraints a bit. A critical path can be made multicycle path by making some design changes.
For false path find attched a basic tutorial. Its realy good and help ful in understanding false path