| 摘要 |
PURPOSE:To prevent increase in error rate even if multi-value is increased by providing the 1st and 2nd memory circuits outputting a digital value of a designated address by taking an input signal as an address signal and inputting the output of the 1st and 2nd memory circuits to the 1st and 2nd D/A converters respectively. CONSTITUTION:An input signal of N-bit is inputted as an address signal of memory circuits 20, 20'. A modulating section 10 is the similar constitution as a conventional circuit. Since the output data of the 1st and 2nd memory circuits has M-bit and then an output signal of D/A converters 1, 1' is formed into values of M-way, the size of the analog signal is adjusted minutely by selecting as M>N/2. Thus, a correct output signal is obtained by storing a digital value where an analog signal corrected in advance is outputted from the D/A converters 1, 1' so that the output of a coupling circuit 6 is placed at a correct position on a signal space. That is, the digital value where the nonlinear distortion and phase deviation or the like of the modulators 3, 3' or the like are corrected in advance for the compensation is stored. |
