In general, the main design advantage of synchronous sequential circuits over…

CONCEPT

A synchronous sequential circuit permits state changes only at defined clock events. The interval between active clock edges allows the combinational logic to settle before the next state is sampled.

An asynchronous sequential circuit has no global clock and may react whenever an input changes. Its correctness therefore depends more directly on propagation-delay relationships, races, and hazards.

APPLICATION

Because state is sampled at specified clock events, a synchronous design can choose a clock period that allows transient glitches in the combinational logic to settle before storage elements capture the next state. This makes hazard-related timing problems easier to contain during design.

CONTRAST

• Faster operation is not a general consequence of synchronization: a clocked circuit may wait for the next active edge, while an asynchronous circuit can proceed after local completion.

• Ease of avoiding hazard problems follows from restricting state capture to defined clock events after a settling interval.

• Lower hardware requirement is not guaranteed because synchronous designs also require clocked storage and a clock-distribution network.

• Noise immunity primarily depends on logic-family noise margins and physical circuit design rather than on the presence of a global clock alone.

CROSS-CHECK AND RESULT

NPTEL notes that the absence of a global clock makes correct asynchronous-circuit design considerably more challenging, which agrees with the timing argument above. Therefore, the best-supported offered answer is ease of avoiding problems caused by hazards.