| 摘要 |
PURPOSE: An automatic gain controller for a digital television is provided to increase the speed and the accuracy by performing a feedback of a gain up signal or a gain down signal, and by performing an AGC in a data block as the unit of 1 data segment regardless of a synchronous signal. CONSTITUTION: A tuner(12) tunes a signal received through an antenna(11) and selects a frequency of a channel. The tuner(12) converts the frequency into an intermediate frequency signal. An FPLL unit(13) demodulates an IF signal outputted from the tuner(12) and locks a frequency and a phase. The FPLL unit(13) adjusts a gain according to a gain control signal upward and downward and outputs a gain control signal to the tuner(12). An analog/digital conversion unit(14) converts analog data demodulated by the FPLL unit(13) into digital data of 10 bits. An input control unit(15) sets a timing as the unit of 10 bits. A DC removal unit(16) removes a DC component from data of the input control unit(15). A polarity correction unit(17) discriminates and corrects a polarity of the data processed by the DC removal unit(16). An AGC control unit(18) extracts gain information from output data of the A/D conversion unit(14) or the DC removal unit(16).
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