DISTORTION COMPENSATING DEVICE

摘要

A distortion compensating device which inputs to a distortion device an input signal distortion-compensated by using a distortion compensation coefficient, computes a distortion compensation coefficient based on a pre-distortion-compensation input signal and a feedback signal fed back from the output side of a distortion device, and stores the computed distortion compensation coefficient correlated to the input signal, wherein (1) a feedback signal is AD-converted, (2) the AD-converted output is subjected to fast Fourier transform (FFT), (3) one of values, a signal noise ratio SNR, or an adjacent channel leakage power ratio ACLR, or a noise level, is calculated using the FFT computation result, (4) a delay time occurring between the distortion device and a feedback loop is regulated so that the difference between the calculated value at the current time and that at a time one time earlier is zero or up to a threshold value, and (5) this regulating is repeated until an accurate delay time is determined and respective units of the distortion compensating device are timed to one another.