Patent ID: 6864745

Claim:
distortion compensation device, which uses distortion compensation coefficients to subject distortion compensation processing to an input signal and supply the result of the distortion compensation processing to a distorting device, calculates the distortion compensation coefficients based on the input signal before distortion compensation and on the feedback signal fed back from the output side of the distorting device, and stores the calculated distortion compensation coefficients in association with the input signal, comprising: an AD conversion portion, which AD-converts said feedback signal; an FFT calculation portion, which performs fast Fourier transform processing of the output of the AD conversion portion, to calculate a spectrum; a calculation portion, which, based on the FET calculation results, calculates either the signal-to-noise ratio SNR, or the adjacent channel leakage power ratio ACLR, or the noise level Pn, or the effective number of bits ENOB; a delay time determination portion, which compares said calculated value at the current time and said calculated value at the immediately preceding time, and based on the comparison result, delay time of the signal generated in the distorting device and the feedback loop, and repeats the delay time determination processing to determine said delay time; and, a delay circuit, in which said delay time is set, and which performs timing adjustment of each of the portions of the distortion compensation device.