Three configuration circuits of field effect transistor a

Three configuration circuits of field effect transistor a

Field effect transistors, like transistors, also have an amplification effect, but unlike ordinary transistors, which are current-controlled devices, field effect
transistors are voltage-controlled devices, which have the characteristics of high input impedance and low noise.
    The three electrodes of the field effect transistor, the gate , source and drain are equivalent to the base, emitter and collector of the transistor respectively. The figure
shows three configuration circuits of field effect transistors, namely common source, common drain and common gate amplifier . Figure 1-21 (a) shows a common source amplifier, which is equivalent
to the common emitter amplifier in a triode and is the most commonly used circuit. Figure (b) shows a common-drain amplifier, which is equivalent to a transistor
common-collector amplifier. The input signal is input from between the drain and the gate, and the output signal is output from between the source and the drain. This circuit is also called Source
output or source follower. Figure 1-21 (c) shows a common-gate amplifier, which is equivalent to a transistor common-base amplifier. The input signal is
input from between the gate and the source, and the output signal is output from between the drain and the gate. The high frequency characteristics of this amplifier are better.
    The input resistance of the insulated gate field effect transistor (MOS) is very high. If charges are induced on the gate, it is difficult to discharge and can easily
break down the PN junction and cause damage. In order to avoid PN junction breakdown damage, the three poles of the field effect tube should be short-circuited during storage: do not store it in a place with a strong
electrostatic field. If necessary, place it in a shielded box; when welding, in order to avoid electric shock The soldering iron has an induced charge, so the soldering iron should be unplugged from the power source
; after soldering into the circuit board, the grid cannot be left floating.