Key advantage of CMOS over TTL: Across logic families, a widely cited advantage of CMOS (Complementary Metal-Oxide-Semiconductor) over TTL is its very low static power consumption. Is this statement correct?

Introduction / Context:When choosing a logic family, designers balance power, speed, noise margins, and cost. CMOS logic is renowned for extremely low static power because, ideally, only leakage current flows when a gate is not switching. TTL, based on bipolar junction transistors, draws more static current by design.

Given Data / Assumptions:

• CMOS static power is dominated by leakage; dynamic power scales with switching activity: P_dynamic = C_load * V^2 * f.
• TTL consumes notable static bias currents regardless of switching.
• We consider mainstream devices at nominal supply voltages (for example, 5 V legacy, 3.3 V/2.5 V/1.8 V modern CMOS).

Concept / Approach:The fundamental CMOS inverter draws current primarily during transitions when both pMOS and nMOS briefly conduct and when charging/discharging capacitive loads. Thus, at low activity, total power is very low. TTL maintains bias currents even at DC, leading to higher static power consumption than CMOS.

Step-by-Step Solution:

Verification / Alternative check:Datasheet quiescent current (ICC) values show orders-of-magnitude difference in favor of CMOS families (for example, HC, HCT, LVC) compared to TTL.

Why Other Options Are Wrong:

Common Pitfalls:Confusing static with dynamic power; ignoring that heavy capacitive loads and high frequency can make CMOS power significant—yet its static power remains far below TTL.

Final Answer:Correct