Patent ID: 7852967
Filing Date: 2010-12-14
Classification: H03F,H03G

Abstract:
1. An automatic power output control circuit applied to a power amplifier capable of changing a setting of a power output level by changing an idling current of a driver, comprising: a gain control section which changes a loop gain for automatic power output control according to the power output level set in the power amplifier; an output voltage detection section which detects an output voltage of the power amplifier; and a comparator which compares the output voltage detected by the output voltage detection section with a reference voltage and performs differential amplification operation on the basis of a difference between the output voltage and the reference voltage, wherein the gain control section comprises a circuit capable of changing a gain of the comparator according to the power output level set in the power amplifier and comprising a current mirror circuit which is connected to an output of a differential amplifier circuit of the comparator and in which each of a plurality of transistors having different sizes is current-mirror connected to a transistor, and a selection circuit which selects one of outputs of the plurality of transistors having the different sizes.