Integrated-circuit families – in modern digital systems and VLSI, is complementary metal–oxide–semiconductor (CMOS) generally the more dominant IC technology compared with classic TTL logic, considering power, density, and scalability?

Introduction / Context:
Over decades of digital design, technology has shifted from bipolar transistor–transistor logic (TTL) to complementary metal–oxide–semiconductor (CMOS). This question asks whether CMOS is indeed the dominant technology today and why that is the case in the context of logic ICs and large-scale integration (VLSI).

Given Data / Assumptions:

• Dominance is judged by market share, integration level, power efficiency, and scalability.
• CMOS here includes all modern process nodes used in microcontrollers, CPUs, FPGAs, ASICs, and standard logic.
• TTL refers to classic bipolar families (74, 74LS, 74ALS, etc.).

Concept / Approach:
CMOS offers extremely low static power (ideally near zero when not switching), very high integration density, and superb scalability with process shrinks. Leakage and dynamic power are managed by device engineering and clock gating. In contrast, TTL uses bipolar transistors with higher static currents and does not scale to nanometer nodes for VLSI. Modern “TTL-compatible” logic levels are actually implemented in CMOS (for example, 74HC/74HCT/74LVC), reflecting CMOS’ practical dominance while maintaining TTL-level interfacing when needed.

Step-by-Step Solution:

Verification / Alternative check:
Data books for current logic families show 74HC/HCT/LVC/AUP/etc., all CMOS. TTL (LS/ALS) is legacy and niche due to higher power and limited speed/voltage flexibility relative to modern CMOS options.

Why Other Options Are Wrong:
“Incorrect” contradicts industry reality. “Only for 4000-series” is too narrow: modern CMOS spans many families beyond 4000-series. Frequency and analog qualifiers do not define dominance across digital ICs.

Common Pitfalls:
Confusing “TTL-compatible voltage levels” with TTL technology; many CMOS parts accept TTL-level inputs without being TTL internally.

Final Answer:
Correct