Hybrid logic families Which logic technology combines the advantages of CMOS (low power, high input impedance) with the speed or drive of bipolar TTL devices?
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ABiCMOS
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BTTL/CMOS
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CECL
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DTTL/MOS
Answer
Correct Answer: BiCMOS
Explanation
Introduction / Context:Modern integrated circuits often blend device types to optimize speed, power, and drive. The term for a technology that integrates both bipolar and CMOS transistors on the same die is crucial when evaluating families that promise “best of both worlds.”
Given Data / Assumptions:
- CMOS benefits: very low static power, high noise margins, excellent scaling.
- Bipolar (TTL-like) benefits: strong drive currents, fast analog behavior in certain regions.
- Goal: combine these advantages.
Concept / Approach:
BiCMOS technology integrates Bipolar Junction Transistors (BJTs) with CMOS on a single chip. CMOS handles most logic functions efficiently, while bipolar devices provide high-current output stages or fast analog interfaces, enabling improved speed and drive without losing CMOS efficiency.
Step-by-Step Solution:
Identify hybrid process → “Bi” (bipolar) + “CMOS”.Match to benefits → low power + higher drive/speed.Select BiCMOS as the correct logic family.Verification / Alternative check:
Common parts like high-speed buffers and microprocessors historically employed BiCMOS output drivers to achieve strong drive while keeping core logic CMOS.
Why Other Options Are Wrong:
- TTL/CMOS or TTL/MOS are informal phrases, not established process names.
- ECL is a distinct high-speed bipolar family with constant-current operation, not CMOS-hybrid.
Common Pitfalls:
- Assuming any TTL-compatible input means it is a “hybrid”; compatibility does not define the process.
Final Answer:
BiCMOS