| 摘要 |
PURPOSE:To realize an A-class push-pull amplifier which features a high efficiency and low distortion rate by varying the bias voltage of the output-step transistor in accordance with the output. CONSTITUTION:The difference of the input potential and the output potential is detected by operational amplifier A1 between output-step transistors Tr7 and Tr8 and then applied to the base of transistor Tr2 forming the bias voltage circuits of Tr7 and Tr8. No cut-off state is given to Tr2 since the emitter is connected to the constant current source, and at the same time Tr2 is so set as not to be saturated completely by diode D1. Thus transistors Tr7 and Tr8 always operate only at the driving region. So is for output-step transistors Tr9 and Tr10 of the other side which constitute a push-pull amplifier. |
