Why CMOS logic is favored in modern digital design Which option best captures the primary advantages that make CMOS logic a strong all-around choice?

Difficulty: Easy

Correct Answer: low power consumption and very high noise immunity

Explanation:


Introduction / Context:
Complementary metal-oxide-semiconductor (CMOS) logic underpins nearly all modern digital integrated circuits, from microcontrollers to CPUs. Understanding its key benefits explains its dominance over other logic families.


Given Data / Assumptions:

  • CMOS uses complementary pairs of MOSFETs (n-channel and p-channel).
  • Static (dc) power consumption is minimal when inputs are not switching.
  • Noise margins are typically large compared to bipolar TTL at similar supply voltages.


Concept / Approach:
In CMOS, one transistor of the complementary pair is OFF for a given static input, so negligible dc current flows from VDD to ground, yielding very low static power. Also, rail-to-rail logic levels and high input impedance provide strong noise immunity. While high packing density is a historical benefit of MOS scaling, the standout universal advantages are low power and high noise immunity.


Step-by-Step Solution:
Identify key metrics: power, noise margin, density.CMOS power: minimal static, dynamic mainly due to charging/discharging capacitances.Noise: wide logic swings and high input impedance improve margins.Therefore, the best single choice combining the core benefits is low power consumption and very high noise immunity.


Verification / Alternative check:
Compare CMOS to TTL: TTL has higher static current draw and generally smaller noise margins at 5 V. Modern low-VDD CMOS retains good margins via proper thresholds.


Why Other Options Are Wrong:
Packing density alone: beneficial but not the sole or primary all-around reason.Low power only: misses the equally important noise immunity.Very high noise immunity only: incomplete without noting low power.


Common Pitfalls:
Assuming CMOS consumes no power; dynamic power can be substantial at high frequency. Also, leakage rises with advanced nodes; still, CMOS remains superior overall.


Final Answer:
low power consumption and very high noise immunity

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