The circuit features of XA8800MNE
Designed as a separate mono-channel structure, XA8800MNE is a full symmetrical current negative feedback Class A amplifier. The main circuit theory and technical features are as following:
The input buffering amplifying stage adopts fast and wide-frequency amplifying circuit with cross coupling compensatory structure. It could connect the push-pull amplifying dynatron as Darlinton circuit and control base current at a low level, ensuring the stabilization of the middle point voltage. Meanwhile, the adoption of transistor Constant Current Source as load ensures the steady and liable work on the stage.
Darlinton complex structure on the Voltage amplifying stage not only ensures enough voltage gain but also raises the input impedance to reach excellent match between the different stages. Besides, the adoption of Cascode circuit offers a good solution of the effect on the high frequency by the transistor junction capacitance. Thus the frequency width could be raised, the output characteristic curve of the bipolar transistor could be improved, the distortion of this stage could be reduced and high stabilization could be achieved.
On the current drive stage, it adopts high power FET to supply drive current for the end stage. The parallel output transistors on the end stage could reduce the output impedance, increase the output power, and improve the load capability with low resistor.
The static working current of 6 pairs high power transistors on the end stage as parallel output is about 300mA and each transistor works in the special linear area where current is higher. This could eliminate crossover distortion and switch distortion efficiently and reduce the output impedance. Equipped with impedance compensatory network including L?Rs?Rz and C on the output terminal, the load of this unit will be closer to pure resistor and difficult to cause self-excitation. Meanwhile, it could afford bigger damp to enhance the controlling ability of this unit to the loudspeaker.