IC logic-family benchmarking A common and practical figure of merit used to measure and compare the overall performance of an integrated-circuit (IC) logic family is the speed–power product (also called the energy–delay product for one switching event).

Introduction / Context:
When evaluating digital IC logic families (for example, TTL, CMOS, ECL), designers want a single number that captures both how fast gates can switch and how much power they consume doing so. The speed–power product provides exactly this: it multiplies typical propagation delay by typical power dissipation to estimate the energy per switching event at a given operating point, enabling apples-to-apples comparisons across families and subfamilies.

Given Data / Assumptions:

• The statement claims that the speed–power product is a common means to compare overall performance.
• Propagation delay (t_pd) and power dissipation (P) are available on every logic-family data sheet.
• We assume worst-case or typical values are chosen consistently when computing the product.

Concept / Approach:
The figure of merit is defined as SPP = t_pd * P. Lower is better because it indicates a gate that both switches quickly and wastes little power. While no single number covers every nuance (drive strength, noise margin, fan-out, voltage range), the speed–power product is widely used to characterize efficiency across families and process generations.

Step-by-Step Solution:

Verification / Alternative check:
Designers also look at energy per transition derived from dynamic power formulas (P ≈ C * V^2 * f). For a fixed load and voltage, lower t_pd often correlates with lower energy per operation in advanced families, reinforcing the usefulness of a combined metric like SPP.

Why Other Options Are Wrong:
“Incorrect” ignores the broad industry usage of this metric. “Applies only to analog ICs” is irrelevant; SPP is a digital logic metric. “Meaningless without fan-out” is misleading; while fan-out influences delay and power, SPP remains a standard comparative measure when referenced to specified test conditions.

Common Pitfalls:
Treating SPP as the only criterion and ignoring noise margin, I/O drive, voltage range, or cost. Another pitfall is mixing typical and worst-case numbers across families, which can skew comparisons.

Final Answer:
Correct