Updated: Dec 9, 2025 | Source: 2023-2027 Question Pool | Topic: G6A
G6A07G6A

What are the operating points for a bipolar transistor used as a switch?

Deep Dive: G6A07

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.

Why Other Answers 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.

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 Example

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.

Source & Coverage

Question Pool: 2023-2027 Question Pool

Subelement: G6A

Reference: 2023-2027 Question Pool · G6 - Circuit Components

Key Concepts

Bipolar transistor Switch operation Saturation and cutoff Transistor switching

Verified Content

Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G6A topic.