Hardware Design Interview Question:

Suppose you have a combinational circuit between two registers driven by a clock. What will you do if the delay of the combinational circuit is greater than your clock signal?

Submitted by: Administrator

Use the concept of register-retiming.
divide the total combinatorial delay in two segments such that individually the delay is less the clock period.
this can be done by inserting a flip-flop in the combinational path.
e.g,
clock period --- 5 ns
total cominational delay ---- 7
then divide the 7ns path in two path of 4 or 3 (best results are obtained if delays are same for both path i.e 3.5ns) by inserting a flip-flop in between.
Submitted by: Administrator