| 摘要 |
PURPOSE:To improve the efficiency of an amplifier, by providing a means clamping an output to an amplifier power supply until an output voltage of a main transistor (TR) reaches a prescribed voltage so as to reduce the collector loss of the main TR and the amplifying circuit. CONSTITUTION:The main TRs12A, 12B of the power amplifier drive a load 14 in response to an input signal from a driver 10 and a prescribed voltage is outputted from fixed power supplies 16A, 16B. Further, a voltage is applied from the power supplies 16A, 16B by the amplifier power supply 28. An output voltage is generated in response to the output voltage of the TRs12A, 12B and the output voltage of the power supply 28 floats floating power supplies 24A, 24B. A larger voltage out of the floating voltages 24A, 24B and the output voltage of the power supplies 16A, 16B is selected at priority circuits 30A, 30B and applied to the TRs 12A, 12B. Zener diodes 34A, 34B and diodes 36A, 36B are connected across a resistor 32 of a base of TRs22A, 22B of the power supply 28 so as to clamp the output voltage of the TRs12A, 12B. Thus, the operating efficiency of the amplifier is improved. |
