Patent ID: 7183847

Claim:
A multi-band look-up table type predistorter that compensates for power amplifier distortions, said predistorter comprising: N first band signal extractors configured to extract transmission signals of N frequency bands from an input signal, said N being an integer equal to or greater than 2; N difference detectors each of which detects the difference between one of said N frequency-band transmission signals and the power amplifier output signal of the same frequency band as said one frequency band signal; N look-up tables from each of which compensation data of said one frequency band is read out, using the detected difference of said one frequency band as a reference signals; N adders each of which adds the compensation data read out of one of said N look-up tables to the transmission signal of the corresponding frequency band; a combiner configured to combine the added outputs from said N adders; and N second band signal extractors configured to extract from the output signal of said power amplifier said signals of the same frequency bands as said N frequency bands, respectively, and for applying said signals to said N difference detectors; wherein said N second band signal extractors are each formed by a cascade connection of N- 1 band elimination filters each of which eliminates the frequency bands of the other remaining N- 1 second band signal extractors.