Classification of Field-Effect Transistors (FETs)

1. Junction Field-Effect Transistors (JFETs)

• Structure: Feature a P-N junction between the gate and an N/P-type channel, with no insulating layer.

• Operation: Reverse-biasing the gate expands depletion regions, narrowing the channel to control drain current (ID).

• Types: N-channel (majority carriers: electrons) and P-channel (holes).

• YFW Advantage: Low noise and high input impedance (10¹⁰ Ω+) make them ideal for audio preamps and sensor interfaces.

2. Metal-Oxide-Semiconductor FETs (MOSFETs)

• Core Design: Include an insulating SiO₂ layer between the gate and channel, enabling ultra-high input impedance (>10¹² Ω).

• Subtypes:

• Enhancement-Mode: Require a threshold voltage (VTH) to form a channel (e.g., N-channel turns on when VGS > VTH, dominant in digital logic and power switching.

• Depletion-Mode: Conduct at VGS = 0; negative gate voltages reduce current, suitable for analog amplification and high-frequency circuits.

• YFW Innovation: Wide-bandgap materials (SiC, GaN) in MOSFETs handle up to 1200V and 100 MHz, optimizing efficiency in EVs and renewable energy systems.

Choosing the Right FET