What happens when the level of a comparator’s input signal crosses the threshold voltage?
The correct answer is B: The comparator changes its output state. What happens when the level of a comparator's input signal crosses the threshold voltage is that the comparator changes its output state. Comparators switch output when input crosses threshold. For amateur radio operators, this is important for digital circuits. Understanding this helps when using comparators.
Exam Tip
Comparator input crosses threshold = comparator changes output state. Think 'C'omparator 'T'hreshold = 'C'hanges 'T'ransition. Comparators switch output when input crosses threshold. Not input damage, not reference level, not feedback instability - just changes output state.
Memory Aid
"Comparator input crosses threshold = comparator changes output state. Think 'C'omparator = 'C'hanges state. Comparators switch output when input crosses threshold. Important for digital circuits."
Real-World Application
When a comparator's input signal crosses the threshold voltage: The comparator changes its output state. If input goes above threshold, output goes high; if input goes below threshold, output goes low. This is what happens - output state changes.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. IC input can be damaged isn't what happens - comparator changes output state. Input damage isn't what happens.
Option C: Incorrect. Reference level appears at output isn't what happens - comparator changes output state. Reference level isn't what happens.
Option D: Incorrect. Feedback loop becomes unstable isn't what happens - comparator changes output state. Feedback instability isn't what happens.
题目解析
The correct answer is B: The comparator changes its output state. What happens when the level of a comparator's input signal crosses the threshold voltage is that the comparator changes its output state. Comparators switch output when input crosses threshold. For amateur radio operators, this is important for digital circuits. Understanding this helps when using comparators.
考试技巧
Comparator input crosses threshold = comparator changes output state. Think 'C'omparator 'T'hreshold = 'C'hanges 'T'ransition. Comparators switch output when input crosses threshold. Not input damage, not reference level, not feedback instability - just changes output state.
记忆口诀
Comparator input crosses threshold = comparator changes output state. Think 'C'omparator = 'C'hanges state. Comparators switch output when input crosses threshold. Important for digital circuits.
实际应用示例
When a comparator's input signal crosses the threshold voltage: The comparator changes its output state. If input goes above threshold, output goes high; if input goes below threshold, output goes low. This is what happens - output state changes.
错误选项分析
Option A: Incorrect. IC input can be damaged isn't what happens - comparator changes output state. Input damage isn't what happens. Option C: Incorrect. Reference level appears at output isn't what happens - comparator changes output state. Reference level isn't what happens. Option D: Incorrect. Feedback loop becomes unstable isn't what happens - comparator changes output state. Feedback instability isn't what happens.
知识点
Comparator's input signal, Crosses threshold voltage, Comparator changes output state
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.