Field effect transistors are divided into junction field effect transistors (JFET) and insulated gate field effect transistors (MOS transistors). According to the channel material type and insulated gate type, there are two types: N channel and P channel. According to the conduction mode: depletion type and enhancement type, junction field effect transistors are both depletion type, and insulated gate field effect transistors are both depletion type and enhancement type. Field effect transistors can be divided into junction field effect transistors and MOS field effect transistors, and MOS field effect transistors can be divided into N-channel depletion type and enhancement type. P-channel depletion type and enhancement type.