Visualise MOSFET ID vs VGS and ID vs VDS characteristics; explore triode and saturation regions
A MOSFET is a voltage-controlled device: gate voltage VGS controls drain current ID with virtually zero gate current. This makes MOSFETs ideal for high-input-impedance circuits and high-efficiency switching.
Cutoff: VGS < Vth, channel closed. Triode (linear): VGS > Vth and VDS < VGS−Vth — resistive switch mode, very low RDS(on). Saturation: VDS ≥ VGS−Vth — constant-current amplifier region.
MOSFETs dominate digital logic (CMOS) and power switching. BJTs remain preferred in RF/microwave amplifiers and precision analog circuits where their exponential I-V characteristic is useful.