How Source Grounded Amplifiers Work

How Source Grounded Amplifiers Work

(2) Working principle of field effect transistor (FET) amplifier circuit
    ① Source grounded amplifier. The source grounded amplifier is the most important circuit form of a field effect tube amplifier . Its working principle
is shown in the figure. In the figure, when the input AC voltage U is on an increasing trend within a 1" period, therefore during this period, the drain current fD increases. The increase of fD increases the voltage drop
on the load . is large, UDS will decrease; when "in the 2/4 cycle, it is in a decreasing state, and Uos increases. fD decreases, and the decrease of lD reduces the voltage drop on the load , and Uos increases. By analogy, the input and output signal waveform states are shown in Figure 1-25. Ui and fD have the same phase and are opposite to the phase of the output signal voltage UDS.