| 摘要 |
PROBLEM TO BE SOLVED: To compensate for the distortion of wideband signals without being subject to restrictions by a sampling frequency of a D/A converter, in a predistortion type power amplifier. SOLUTION: A wideband signal is frequency-divided, and digital predistortion sections 101-104 are provided, corresponding to each frequency. After a predistortion process, the frequency-divided signals are upconverted into each frequency region by means of modulation sections 131-134. The upconverted signals are combined by a power combiner 51, to obtain an inverse function for input/output characteristics of a power amplifier 61. The combined signal is amplified by the power amplifier 61. Thus, by combining a plurality of digital input signals, any wideband signal can be generated, and therefore wide-band distortion signals resulting from the input of a multicarrier into the power amplifier can be reduced. Consequently, an amplifier which can keep linearity over a wide band can be formed. |
