Logic families versus hallmark characteristics: Match the logic family with its most typical characteristic. List I (Family) List II (Characteristic) A. TTL 1. Maximum power consumption B. ECL 2. Highest packing density (within classic NMOS/CMOS/TTL/ECL context) C. NMOS 3. Least power consumption D. CMOS 4. Saturated logic (bipolar, switching into saturation)
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AA-1, B-4, C-2, D-3
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BA-1, B-4, C-3, D-2
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CA-4, B-1, C-2, D-3
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DA-4, B-1, C-3, D-2
Answer
Correct Answer: A-4, B-1, C-2, D-3
Explanation
Introduction / Context:Each logic family trades speed, power, and density differently. Knowing their signatures helps in both digital design history and exam matching problems.
Given Data / Assumptions:
- Classic families (TTL, ECL, NMOS, CMOS) considered.
- We focus on hallmark traits, not every variant.
- Relative comparisons: ECL draws high static power; CMOS excels in low power.
Concept / Approach:
TTL is a saturated bipolar family, ECL avoids saturation for speed but at high power, NMOS historically achieved high integration density before CMOS dominance, and CMOS minimizes power via complementary transistors with near-zero static current in ideal logic states.
Step-by-Step Solution:
TTL → Saturated logic ⇒ A-4.ECL → Maximum power consumption (very fast, constant bias currents) ⇒ B-1.NMOS → High packing density in the pre-CMOS era ⇒ C-2.CMOS → Least power consumption (static) ⇒ D-3.Verification / Alternative check:
Datasheets and textbooks consistently profile ECL as high-power/high-speed, TTL as saturated bipolar, NMOS as dense but power-hungry, and CMOS as low-power with massive modern density.
Why Other Options Are Wrong:
- Assigning lowest power to TTL conflicts with its bipolar nature.
- Calling NMOS “least power” contradicts static DC paths in pull-ups.
- Labeling CMOS “saturated logic” misstates its operation.
Common Pitfalls:
Projecting today’s CMOS leadership in density back onto historical NMOS/TTL contexts; this item targets hallmark, not current-market outcomes.
Final Answer:
A-4, B-1, C-2, D-3