ring counter at 0.35um process

[paramis]

Hi all,
I need a ring counter with 50 latch, that worked with clock @ frequency=4.3Ghz,i use c2mos latch but it can't work correct.
one c2mos latch work correct at 4.3GHz but loop of 50th of c2mos latch didn't work.do u know any high speed latch??? i don't know why loop can't work....
the image of c2mos latch attached.

 

[prestonee]

That is very high speed, perhaps the devices are not sized quite right for the drive loading vs speed, were you simming with parasitics? It sounds like if a single works but the chain isnt, you might have race conditions occurring, have you observed the delay from one to the next with respect of the clock input?

 

[Filip]

I guess that clock bus is loaded with 100 latches and (without buffer amplifiers) it's overloaded.