50W power amplifier 01

So far, single-chip and mixed-power LCs can hardly obtain satisfactory high-frequency characteristics. The circuit shown in Figure 3-31 is the application diagram of Sanyo thick
film LC ST K084G. Within ZOkHz, the output power is 50w and the distortion rate is only 0.003%. oThe
    main part of the circuit has been IC-based, so the external parts are mainly large-capacity capacitors. Figure 3.32 shows the internal circuit of ST K084G
. The input stage consists of a current mirror circuit composed of VT4 and VT5 , which converts the PNP differential amplifier output into a single-ended output
and obtains a larger gain at the same time. The intermediate stage handles large amplitudes and also determines the amplifier conversion rate, so it should be driven with a large
current as much as possible . The common base circuit composed of VT8 eliminates the deterioration of high-frequency characteristics caused by the Miller effect. 6
    VT1 and VT6 are constant current source bias circuits , can suppress the impact caused by power supply fluctuations. VT7 provides
bias for the output transistor, eliminates the nonlinear transition area of ​​the voltage Vbf between the base and the emitter, and also functions as temperature compensation.