OPA604 high performance low power audio power amplifier circuit diagram

As shown in the figure is a high-performance low-power audio power amplifier circuit. The front stage of this circuit uses a field effect tube high-fidelity operational amplifier OPA604 , and the rear stage uses a high-speed buffer BUF634, and voltage series negative feedback is used between the two amplifiers. The voltage amplification factor of this circuit is determined by the two resistors (5kΩ and 250Ω) of the feedback branch, and its value is: l+5kΩ/250Ω≈21 times. BUF634 is a high-speed buffer, and the simplified circuit of the internal structure is shown in Figure (b).