Why we dont consider the hold time of source flip-flop for calculating max. frequency

[sujittikekar1]

can anybody tell why we dont consider the hold time of source flip flop while calculating max. frequency?

 

[go4sandesh_vsn]

Re: maximum frequency

bcoz while calculation we consider "clock to Q" time of flop which automatically includes "hold time" ( as almost all the time clk-to-Q > hold_time)....

so eqn is like

  f = 1/(clk_to_Q + prop_delay + routing_delay + set_up_of_next_flop)

something like this....

P.S. : clk_to_Q itself includes hold time

 

[lordsathish]

Re: maximum frequency

Hold time is some thing that affects the performance only after the clock arrives... so we have to only cosider only the computational delay of the circuit...

 

[Fahmy]

maximum frequency

I think that hold time does not affect the maximum operating frequency you can work with at all. It sets a limit for the minimum allowable clock-to-Q and propagation delays , such that Tcq+Td > Thold.
ALso it puts a limit on the skew between CLK at different clocked elements.