Do both IMPATT and TRAPATT microwave diodes rely on the avalanche effect as part of their operation?
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ATrue
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BFalse
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CTrue, but only above 100 GHz
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DFalse, only TRAPATT is avalanche-based
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EFalse, only IMPATT is avalanche-based
Answer
Correct Answer: True
Explanation
Introduction / Context:IMPATT (IMPact Avalanche Transit-Time) and TRAPATT (TRApped Plasma Avalanche Triggered Transit) diodes are negative-resistance microwave devices used in oscillators and amplifiers.
Given Data / Assumptions:
- Both devices use avalanche breakdown to initiate carrier multiplication.
- Transit-time effects provide the necessary phase delay for negative resistance.
Concept / Approach:In IMPATT, carriers generated by avalanche are swept across the drift region, producing a 180° current–voltage phase shift. TRAPATT also starts with avalanche, but operates with a trapped plasma domain and typically exhibits higher efficiency and lower operating frequency than IMPATT.
Step-by-Step Solution:
Avalanche multiplication → carrier surge.Transit-time through drift region → phase delay leading to negative resistance.Both devices depend on the avalanche trigger to start the process.Verification / Alternative check:Standard microwave device references categorize both as avalanche transit-time devices, differing in domain dynamics and efficiency.
Why Other Options Are Wrong:
Statements that only one is avalanche-based are incorrect.Frequency limits (e.g., 'only above 100 GHz') are irrelevant to the avalanche principle.Common Pitfalls:
Confusing Gunn diodes (transferred electron effect) with avalanche devices.Final Answer:
True