Compared to bipolar transistors (BJTs), field-effect transistors (FETs) have the following characteristics:
(1) FETs are voltage-controlled devices, controlling the drain current (ID) via VGS (gate-source voltage);
(2) The control input current of an FET is extremely small, resulting in a very high input resistance (10⁷–10¹² Ω);
(3) FETs utilize majority carriers for conduction, thus exhibiting better temperature stability;
(4) The voltage amplification factor of an amplifier circuit composed of FETs is smaller than that of an amplifier circuit composed of bipolar transistors;
(5) FETs have strong radiation resistance;
(6) FETs have low noise because they do not exhibit shot noise caused by the diffusion of stray electrons.
