Power amplifier using field effect transistor as output

The circuit principle is shown in Figure 2-2. It consists of an input stage, a voltage push stage and a power output stage. Except for the input and output stages
, direct coupling is used between all stages.
    VTi and its peripheral components form the input stage, and its output is directly coupled to the base of the driving stage VT3. VT2 is
the constant current source load of VT3.
    VT4 and VTs are composed of field effect power tubes to form a complementary push-pull power amplifier output stage o
    Rs; Min and island form a feedback system, which determines the gain of the whole circuit: Av = R8/R6 about 26dBo.
Adjust Rio so that the quiescent current of VT4 is lOOmA.
Technical indicators:
Output power: Po= 32W (8fl);
Frequency response: 20Hz~ 22kH (-3dB);
Signal-to-noise ratio : >90dB;
Total harmonic distortion: <o-05%0