Technology identification: Complementary metal–oxide–semiconductor (CMOS) logic uses MOSFET devices, not bipolar junction transistors (BJTs). Evaluate the claim that CMOS uses bipolar transistors instead of MOSFET.

Difficulty: Easy

Correct Answer: Incorrect

Explanation:


Introduction / Context:
CMOS is defined by its use of complementary pairs of MOSFETs (nMOS and pMOS). Bipolar technologies (TTL/ECL) rely on BJTs and have different characteristics for speed, power, and fanout. The question tests recognition of device technology behind CMOS.


Given Data / Assumptions:

  • CMOS stands for complementary metal–oxide–semiconductor.
  • Core switching elements are MOSFETs (field-effect transistors).
  • Bipolar logic families use BJTs rather than MOSFETs.


Concept / Approach:
CMOS logic pairs p-channel and n-channel MOSFETs to implement low static power gates with rail-to-rail swings. BJTs appear in bipolar families (e.g., TTL), not in CMOS gate cores. While mixed-signal ICs may integrate bipolar for analog blocks (BiCMOS), pure CMOS gates remain MOSFET-based.


Step-by-Step Solution:

Identify the expansion of CMOS and the device class it implies (MOSFET).Contrast with bipolar families that depend on BJT conduction.Recognize the claim substitutes BJTs for MOSFETs, which is incorrect for CMOS.Conclude the statement is incorrect.


Verification / Alternative check:
Device cross-sections and gate schematics of CMOS inverters show a pMOS pull-up and nMOS pull-down network, confirming MOSFET usage.


Why Other Options Are Wrong:

  • Correct: Would misidentify CMOS technology.
  • Ambiguous / Cannot be determined: The terms are explicit and standardized.


Common Pitfalls:
Confusing CMOS with BiCMOS; BiCMOS integrates both, but the claim as worded remains false for CMOS itself.


Final Answer:
Incorrect

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