| 摘要 |
PURPOSE: An apparatus and a method are provided to achieve improved output efficiency of low pass filter and prevent errors during an automatic gain control. CONSTITUTION: An apparatus comprises an analog/digital converter(201) for converting the received radio frequency signal into a digital signal; a first mixer(203) and a second mixer(204) for multiplying the output signal from the analog/digital converter and the output signal from a numerically controlled oscillator(202), and outputting an in-phase signal and a quadrature signal; a first low pass filter(205) and a second low pass filter(206) for low pass filtering the outputs from the first and second mixers and outputting the low pass filtered output; a first gain control unit(220) for measuring the output power of the first and second low pass filters, calculating and accumulating the error value between the measured output power and the reference power, and adjusting the volume of attenuation in accordance with the average error value of a sample; and a second gain control unit(230) for controlling the degree of power attenuation of the received analog signal in accordance with the volume of attenuation adjusted by the first gain control unit.
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