Deep Dive: G6A09
The correct answer is B: The gate is separated from the channel by a thin insulating layer. What describes MOSFET construction is that the gate is separated from the channel by a thin insulating layer. MOSFETs have an insulated gate (Metal-Oxide-Semiconductor), unlike bipolar transistors. For amateur radio operators, this is a key MOSFET characteristic. Understanding this helps when using MOSFETs.
Why Other Answers Are Wrong
Option A: Incorrect. The gate isn't formed by a back-biased junction - that's a JFET, not a MOSFET. MOSFETs have insulated gates, not junction gates. Option C: Incorrect. The source isn't separated from the drain by an insulating layer - source and drain are both in the semiconductor. The gate is insulated, not source-drain. Option D: Incorrect. The source isn't formed by depositing metal on silicon - source and drain are semiconductor regions. Metal deposition isn't how source is formed.
Exam Tip
MOSFET construction = gate separated from channel by thin insulating layer. Think 'M'OSFET = 'M'etal-'O'xide-'S'emiconductor = 'G'ate 'I'solated. Gate is insulated from channel by thin oxide layer. Not back-biased junction, not source-drain insulation, not metal deposition - just gate insulation.
Memory Aid
MOSFET construction = gate separated from channel by thin insulating layer. Think 'M'OSFET = 'M'etal-'O'xide-'S'emiconductor. Gate is insulated from channel by thin oxide layer. Key MOSFET characteristic.
Real-World Example
A MOSFET has a gate electrode separated from the semiconductor channel by a thin insulating layer (oxide). This insulated gate allows voltage control without gate current, unlike bipolar transistors. The 'MOS' in MOSFET stands for Metal-Oxide-Semiconductor, referring to this insulated gate structure.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G6A
Reference: 2023-2027 Question Pool · G6 - Circuit Components
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G6A topic.