Patent ID: 9099977
Filing Date: 2015-08-04
Classification: H03F,H03G

Abstract:
1. An amplifier circuit comprising: a first filter that receives input of amplitude information of an input signal, and performs filtering so that a gain of a frequency component higher than a first cutoff frequency becomes greater than a gain of a frequency component lower than the first cutoff frequency; a power supply circuit that has a low-pass filter characteristic that a gain of a frequency component lower than a second cutoff frequency is greater than a gain of a frequency component higher than the second cutoff frequency, and receives input of amplitude information outputted from the first filter and generates a power supply voltage corresponding to the amplitude information outputted from the first filter; an amplifier that receives supply of the power supply voltage generated by the power supply circuit, and amplifies a signal based on the input signal; and a phase difference detector that detects a phase difference between the amplitude information of the input signal and the power supply voltage generated by the power supply circuit, wherein the first filter changes the first cutoff frequency in a direction in which the phase difference detected by the phase difference detector decreases.