Patent ID: 7202745
Filing Date: 2007-04-10
Classification: H03F

Abstract:
1. A power amplifier circuit comprising: a power amplifier; a switching device for selectively connecting either a low-voltage power supply or a high-voltage power supply to the power amplifier; means for generating a signal voltage in response to a voltage outputted from the power amplifier; a reference-voltage generation circuit for generating a positive-circuit-side reference voltage and a negative-circuit-side reference voltage; and a control circuit for comparing the signal voltage with the positive-circuit-side and negative-circuit-side reference voltages and controlling the switching device in response to results of the comparison so that the low-voltage power supply is connected to the power amplifier when an absolute value of the signal voltage is smaller than absolute values of the positive-circuit-side and negative-circuit-side reference voltages, and that the high-voltage power supply is connected to the power amplifier when the absolute value of the signal voltage is greater than the absolute values of the positive-circuit-side and negative-circuit side reference voltages; wherein the reference-voltage generation circuit comprises a first voltage regulating circuit connected between a positive side of the low-voltage power supply and a first circuit point subjected to a negative potential for generating the positive-circuit-side reference voltage, and a second voltage regulating circuit connected between a negative side of the low-voltage power supply and a second circuit point subjected to a positive potential for generating the negative-circuit-side reference voltage.