Combinational Multiplier vs Sequential Multiplier

Build the multiplication result through a combinational network.

Main Strategy of a Combinational Multiplier

Reuse a datapath across multiple clocked iterations

Main Strategy of a Sequential Multiplier

Sequential Multiplier requires states. Controller state must persist the partial results, shifting operands, and counts.

Which multiplier type require States?

Combinational multiplier is relatively small at the operational level, Sequential multiplier requires sequencing and completion control.

Comparison of the Control Complexity of both Combinational and Sequential Multipliers.

Dominated by combinational propagation delay

Operation latency model in a combinational multiplier

Dominated by number of required cycles plus per-cycle timing.

Operation latency model in a sequential multiplier

More parallel arithmetic logic

Likely resource pattern of a combinational multiplier

More reuse of arithmetic hardware over time

Likely resource pattern of a sequential multiplier

Parallel Hardware

Results in:

1. More resource use

2. Fewer cycles per result

3. Different routing/ timing/ power consequences

Serial Hardware

Results in:

1. Fewer arithmetic resources

2. Requiring states + sequencing

3. More cycles per operations