synthesis capture clock

[raj1435]

Hi,

Can any one explain me about capture clock time period in the synthesis timing report. To make it more clear i have the time period of the 10ns,
in the timing report i am seeing the capture clock time period is the half the total time period i.e 5ns.

can any one explain clearly why it was.

Thanks

 

[yuhiub90]

It's called half-cycle path, timing path from posedge to negedge ff.

 

[raj1435]

It will be always half cycle path in the synthesis or full cycle. can you explain me why it will be a half cycle path.

 

[sharath666]

If ur clock is 10 ns and if the launch is at 0ns then the capture will be at 10 ns. If you are seeing capture at 5 ns, then it must be capturing data on the negedge of clock. Otherwise you must have constrained it accordingly. Go back to the RTL and check this particular timing path.

 

[raj1435]

Hi,

can you explain me ,what are the conditions that incorporate a half cycle time period in the RTL. from synthesis constrained point of view i havn't constrained as half cycle.

 

[hoanglongroyal]

Hi,

can you explain me ,what are the conditions that incorporate a half cycle time period in the RTL. from synthesis constrained point of view i havn't constrained as half cycle.

hi Raj1435,
it's not from what you "constraint" the path (in your design). it come from what you designed
- your launch flop L : normal, CK feed clock pin of your flop
- your capture flop C : the CK signal is inverted to original.
--> you launch data from L at rising edge of clock pin L, and then capture data at C - rising edge of clock pin C . but now, rising edge of clock pin C is from falling edge of clock pin L because of inverter in clock path between L and C. so, you have Launch at rising and Capture at falling.
that just a case, maybe you also used a paid pos-neg flops.
so, please check your logic design to see (your netlist)

 

[raj1435]

Hi
Thanks for the reply i understand the issues. i wanted to know what is mean by paid pos-neg flops.

 

[hoanglongroyal]

Hi
Thanks for the reply i understand the issues. i wanted to know what is mean by paid pos-neg flops.

hi Raj,
many sorry about wrong type, I mean PAIR , not PAID