Fully symmetrical complementary CL amplifier

CL type power amplifier circuit is a power amplifier circuit that has neither output capacitor nor feedback capacitor and compensation capacitor. The whole circuit
only consists of transistors (or field effect transistors) and resistors. Components in the circuit that can produce feedback and phase shifts have been removed. Theoretically
, this amplifier can amplify all frequencies of the input signal equally. That is, the input signal
is not modified in any form other than amplification. Figure 2-38 is a fully complementary dual differential input CL power amplifier circuit
    composed of transistors, field effect transistors and resistors . The fully complementary differential circuit     composed of transistors VTi ~ VT4 and the constant current source composed of field effect transistors VPi and VP2 respectively constitute the input stage of this circuit. The field effect transistor constant current source is closer to the ideal constant current source due to its simple structure, no need for bias, good temperature stability and high dynamic internal resistance.     The voltage amplification stage uses a differential balanced amplifier circuit, which is composed of VTs ~ VTio. Since the integrated differential circuit of this stage and the input stage double differential circuit can achieve good matching, the input stage differential circuit works in the best state of double-ended output . It can greatly improve the common mode rejection ratio and reduce the distortion of the input stage. At the same time, this two-stage differential circuit will produce extremely strong DC negative feedback, making the DC operating points of the entire circuit at all levels very stable. basic conditions for sound .     The principle of balanced amplification is: when the signal is in the positive half cycle, VT6 and the lower-level input can be equivalent to a constant current source load, so that the voltage gain of VT8 is one or two orders of magnitude higher than that of the resistive load. When the signal is in the negative half cycle, VT8 The output of the lower stage can be equivalent to a constant current source load, which increases the voltage gain of VT6 by one or two orders of magnitude. This kind of circuit has high gain and low distortion, allowing the output tube to obtain greater driving power.