DC analysis of OTL power amplifier

In addition to the power supply, the input part is an independent structure. VTi is a common emitter amplifier circuit,
R1 and R2 are base bias resistors, code is the load resistor, where and Rs are the DC feedback resistors of the emitter. After the power supply v+
is stepped down by R18, the bias resistor Ri provides the base current, bl, to VTi. Ri is adjusted so that the collector of VTi outputs a quiescent current of 1~
2mA. The lower end of R2 is not grounded, but is connected to Rs. In the middle, its purpose is to improve
the input impedance of the input circuit.
    The push stage and power output stage composed of VT2 and so on are directly coupled, and the circuits are related to each other. Therefore, in the analysis
, they are both systematic and interrelated.
    The collector of VT2 is powered by the power supply V+, and its base bias current is provided by the midpoint D of the power amplifier output stage through the feedback
resistor R6. The collector current IcZ of VT2 flows through the island, VDi, VI)2 and Rco . Among them, R9 is the load
resistor. Although VIHO, VIBah and Rio are at the position of VT2 collector load, due to their small resistance, they are not
part of the VT2 load, but serve as the bias of the output stage VT3 and VTs. setting circuit, which uses the voltage drop (upper positive and lower negative) generated by the VTz collector to provide static bias for VT3 and VTs, so that the output stage works in Class A and B to eliminate the crossover distortion of the output stage o Rlo The adjustable resistor is used to facilitate adjustment to a suitable operating point.