A lookup table type predistorter for reading out distortion compensation
data by using a difference signal between a power amplifier input signal
and an output signal as a reference signal; wherein N input side variable
band signal extractors extract transmitting signals in N frequency bands
from the input signal, N output side variable band signal extractors
extract signals in N frequency bands from the output of power amplifier,
and N difference detectors detect differences between N frequency band
signals respectively detected at the input side and the output side as N
reference signals, which are used to read out N compensation data from N
lookup tables, the N compensation data are added to the transmitting
signals in N frequency bands, and N results of addition are combined to
produce an output of the predistorter.