What are the operating points for a bipolar transistor used as a switch?
The correct answer is A: Saturation and cutoff. The operating points for a bipolar transistor used as a switch are saturation and cutoff. A switch is either fully on (saturation) or fully off (cutoff), not in the active region. For amateur radio operators, this is how transistors work as switches. Understanding this helps when using transistors for switching.
Exam Tip
Transistor switch operating points = saturation and cutoff. Think 'S'witch = 'S'aturation (on) and 'C'utoff (off). Switch is either fully on (saturation) or fully off (cutoff). Not active region (amplification), not peak/valley, not enhancement/depletion - just saturation and cutoff.
Memory Aid
"Transistor switch operating points = saturation and cutoff. Think 'S'witch = 'S'aturation and 'C'utoff. Switch is either fully on (saturation) or fully off (cutoff). Two-state operation for switching."
Real-World Application
You use a bipolar transistor as a switch to control a relay. When the transistor is on, it's in saturation (fully conducting). When it's off, it's in cutoff (not conducting). The transistor switches between these two states - saturation and cutoff - not operating in the active region.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. The active region is for amplification, not switching. Switches operate at saturation (on) and cutoff (off), not in the active region.
Option C: Incorrect. Peak and valley current points aren't transistor operating points - those are different concepts. Not relevant to transistor switching.
Option D: Incorrect. Enhancement and depletion modes are for MOSFETs, not bipolar transistors. Bipolar transistors don't have these modes.
题目解析
The correct answer is A: Saturation and cutoff. The operating points for a bipolar transistor used as a switch are saturation and cutoff. A switch is either fully on (saturation) or fully off (cutoff), not in the active region. For amateur radio operators, this is how transistors work as switches. Understanding this helps when using transistors for switching.
考试技巧
Transistor switch operating points = saturation and cutoff. Think 'S'witch = 'S'aturation (on) and 'C'utoff (off). Switch is either fully on (saturation) or fully off (cutoff). Not active region (amplification), not peak/valley, not enhancement/depletion - just saturation and cutoff.
记忆口诀
Transistor switch operating points = saturation and cutoff. Think 'S'witch = 'S'aturation and 'C'utoff. Switch is either fully on (saturation) or fully off (cutoff). Two-state operation for switching.
实际应用示例
You use a bipolar transistor as a switch to control a relay. When the transistor is on, it's in saturation (fully conducting). When it's off, it's in cutoff (not conducting). The transistor switches between these two states - saturation and cutoff - not operating in the active region.
错误选项分析
Option B: Incorrect. The active region is for amplification, not switching. Switches operate at saturation (on) and cutoff (off), not in the active region. Option C: Incorrect. Peak and valley current points aren't transistor operating points - those are different concepts. Not relevant to transistor switching. Option D: Incorrect. Enhancement and depletion modes are for MOSFETs, not bipolar transistors. Bipolar transistors don't have these modes.
知识点
Bipolar transistor, Switch operation, Saturation and cutoff, Transistor switching
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.