Fully complementary power amplifier

It consists of a two-stage voltage amplifier and a slow complementary current amplifier 6 VTl, VT2.
The first stage differential amplifier uses a constant current diode VDH1 to replace the traditional emitter resistor, which greatly improves
the stability of the ocl-circuit. The input signal
is coupled to the base of VT1 through Cl, Rl is the DC bias resistor of VT1, and C2 is used to filter out high-frequency interference in the input signal. The feedback signal is fed back to the VT2 base by the R3 R4 and C3 network. The first-stage amplified signal is output from
the collector of VTi and is directly coupled to the base of VT3. R5 is the emitter load resistor of VT3, and the constant current diode VDHZ is the collector
load of VT3 . Due to the constant current effect of VDH2, the amplifier excitation stage does not need to use a common bootstrap circuit, thus overcoming the disadvantages of transient characteristics degradation caused by bootstrapping and achieving higher fidelity. VT5. VT6 is a complementary emitter power output device, and C4 is a Miller anti-vibration capacitor.