Patent ID: 7551687
Filing Date: 2009-06-23
Classification: H03F

Abstract:
1. A distortion compensating apparatus for compensating for distortion of a transmission power amplifier, comprising: a memory for storing distortion compensation coefficients, which are for compensating for distortion of the transmission power amplifier, in association with power p of a transmit signal; a predistortion unit for subjecting the transmit signal to distortion compensation processing using a distortion compensation coefficient that conforms to the power p of the transmit signal; a DA converter for converting a digital transmit signal, which has been subjected to distortion compensation processing, to an analog signal and inputting the analog signal to the transmission power amplifier; a distortion compensation coefficient calculation unit for calculating a distortion compensation coefficient based upon the transmit signal before the distortion compensation thereof and a feedback signal fed back from an output side of the transmission power amplifier; a comparison unit for judging whether the transmit signal, which is subjected to the distortion compensation processing using the distortion compensation coefficient calculated by said distortion compensation coefficient calculation unit, exceeds a dynamic range of said DA converter; a distortion compensation coefficient correction unit for correcting the distortion compensation coefficient in such a manner that the transmit signal that has been subjected to the distortion compensation processing does not exceed the dynamic range of said DA converter; and a distortion compensation coefficient updating unit for updating a distortion compensation coefficient, which has been stored in said memory, by the distortion compensation coefficient that has been corrected.