Patent ID: 9735815
Date: 2017-08-15
CPC Classifications: H03F,H04B,H04L

Claim:
1. A radio apparatus comprising: an amplifier that amplifies power of a transmission signal; a first mixer that mixes a feedback signal from the amplifier with a local signal of a predetermined frequency; an analog-to-digital converter that performs analog-to-digital conversion on an output signal of the first mixer; a distortion compensator that compensates nonlinear distortion of the amplifier based on a digital signal obtained by performing the analog-to-digital conversion; and an oscillator that changes a frequency of the local signal to be mixed with the feedback signal in the first mixer in a time division manner, with frequency spacing corresponding to a sampling rate of the analog-to-digital converter, the oscillator generates a first local signal having a central frequency of the transmission signal and a second local signal having a frequency away from the central frequency by an integral multiple of a bandwidth of the transmission signal as the local signal in a time division manner, the first mixer frequency-converts, using the first local signal, the feedback signal to output a first signal in which a main signal component corresponding to the transmission signal falls within a predetermined frequency band, and frequency-converts, using the second local signal, the feedback signal to output a second signal in which a distortion component generated in the frequency falls within the frequency band, the analog-to-digital converter performs analog-to-digital conversion respectively on the main signal component of the first signal and the distortion component of the second signal in the frequency band, and the distortion compensator updates a distortion compensation coefficient to be used for compensation of nonlinear distortion of the amplifier based on a sum of the analog-to-digital converted main signal component and the distortion component and the transmission signal.