In digital logic families, which technology dissipates the minimum static power under typical operating conditions?

Introduction / Context:Different logic families—DTL, TTL, ECL, and CMOS—have distinct trade-offs in speed, noise margins, fan-out, and power dissipation. Power efficiency is critical in battery-operated devices and large-scale integration. This question tests recognition of which family minimizes static power consumption.

Given Data / Assumptions:

• Logic families: DTL, TTL, ECL, and CMOS.
• Typical ambient conditions; nominal supply voltages.
• Focus on static (DC) power dissipation at logic 0/1, not dynamic at high switching rates.

Concept / Approach:

• CMOS (Complementary Metal-Oxide-Semiconductor) uses complementary pairs of MOSFETs.
• In steady states, one device of the pair is OFF, leading to near-zero DC current through the pull-up/pull-down path.
• Other families (TTL/DTL) maintain bias currents; ECL uses differential pairs with constant current, hence higher power.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• DTL: Diode-transistor logic still draws static current via biasing networks.
• TTL: Transistor-transistor logic consumes more static power than CMOS.
• ECL: Highest power due to constant current flow in differential pairs, traded for speed.
• None of the above: Incorrect because CMOS is correct.

Common Pitfalls:

• Confusing static with dynamic power; CMOS dynamic power can be significant at high frequencies (P ≈ C * V^2 * f).
• Assuming ECL is efficient because it is fast; speed does not imply low power.

Final Answer: