Among TTL, CMOS, and ECL logic families, which key advantage is typically attributed to Emitter-Coupled Logic (ECL) compared to TTL and CMOS?

Introduction / Context:
Logic families trade off speed, power, and noise margins. TTL and CMOS are common in general-purpose designs, whereas ECL is chosen when very high-speed switching is paramount.

Given Data / Assumptions:

• ECL operates transistors in the active region, avoiding saturation delays.
• Comparative families: TTL (bipolar, saturating) and CMOS (field-effect, low static power).

Concept / Approach:
By avoiding transistor saturation and using differential pairs, ECL achieves extremely fast transitions at the expense of higher static power consumption and smaller logic swings, which also aids speed but reduces noise margins.

Step-by-Step Solution:
1) TTL: moderate speed, moderate power.2) CMOS: low static power, wide supply range, speed improves with scaling.3) ECL: highest speed (shortest propagation delays) due to non-saturating operation and constant-current biasing.

Verification / Alternative check:
Datasheets show ECL propagation delays markedly lower than comparable TTL/CMOS of similar eras.

Why Other Options Are Wrong:
“low power dissipation” is not an ECL hallmark; “both…” conflicts with ECL’s higher power; “neither…” ignores ECL’s defining speed advantage.

Common Pitfalls:
Assuming CMOS is always fastest; conflating modern high-speed CMOS with classic family comparisons.

Final Answer:
high speed