| 摘要 |
PURPOSE: A digital linearlizer is provided to exactly detect the error values generated during the QPSK modulation by using a digital algorithm as well as to interwork with an arbitrary QPSK modulation block by providing a compensation circuit at the front end of the QPSK modulation block. CONSTITUTION: A digital linearizer includes a predistorter(1) for control a level of a digital input signal and for distorting the digital input signal which is controlled in the level in such a way that the digital input signal which is controlled in the level has a characteristics opposite to a nonlinear distortion characteristics, an error compensation block(100) for receiving I/Q digital signal outputted from the predistorter(1) and outputting by previously compensating the received I/Q digital signal by an error compensation signal, a first digital/analog converter(2) for converting an I-digital signal outputted from the predistorter(1) into an I-analog signal, a second digital/analog convertor(3) for converting a Q-digital signal outputted from the predistorter(1) into a Q-analog signal, a modulation block(10) for modulating the I/Q analog signals outputted from the first and the second digital/analog convertors(2,3) into a frequency of carrier wave and an error compensation signal detection block(200) for implementing a predetermined calculation by receiving the output signal of the modulation block(10) and for outputting the calculated error compensation signal.
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