Distortion compensation apparatus

A distortion compensation apparatus comprising:

• a distortion compensation processing circuit multiplying an input signal by a distortion compensation coefficient;
• a distortion compensation coefficient storage storing the distortion compensation coefficient correspondingly to the input signal power;
• a distortion compensation coefficient calculator calculating an update value of the distortion compensation coefficient stored in the distortion compensation coefficient storage, based on the input signal and a feedback signal being fed back from the output side of a distortion device;
• a digital filter inputting the output of the distortion compensation processing circuit;
• and further,
• a controller modifying the passband of the digital filter so as to reduce a distortion compensation control bandwidth in the predistortion portion, in response to the reduction of the number of carriers in the input signal.

A distortion compensation method comprising:

• multiplying an input signal with a distortion compensation coefficient by a distortion compensation processing circuit;
• storing the distortion compensation coefficient correspondingly to the input signal power in a distortion compensation coefficient storage;
• calculating an update value of the distortion compensation coefficient stored in the distortion compensation coefficient storage, by a distortion compensation coefficient calculator, based on the input signal and a feedback signal fed back from a distortion device;
• inputting the output of the distortion compensation processing circuit to a digital filter;
• and
• modifying the passband of the digital filter so as to reduce a distortion compensation control bandwidth in the predistortion portion, in response to the reduction of the number of carriers in the input signal.