QUESTION 53 For a RTL timing operation, relation between cyclic time and longest critical path?

In RTL (Register Transfer Logic) design, the cycle time of a synchronous circuit must be at least equal to the longest path delay (critical path) between registers, plus setup and hold time margins. The cycle time is fundamentally determined by the critical path—it cannot be shorter or unrelated. The circuit's maximum operating frequency is directly limited by this critical path delay.

Step-by-step Derivation:
In synchronous digital design: Cycle Time (T_clk) ≥ T_critical_path + T_setup + T_hold. For ideal timing analysis, Cycle Time = T_critical_path (the minimum achievable cycle time). Any attempt to run the circuit faster than this would violate timing constraints and cause setup time violations, leading to metastability and errors. Therefore, the cyclic time must equal or exceed the longest critical path, and in timing closure, designers aim for equality as the target.