| 摘要 |
PURPOSE: An apparatus for controlling an auto gain is provided to reduce reducing signal saturation or signal distortion caused by an out-of-band signal of a filter or a delay of a control signal, and precisely measuring a level of an in-band signal of the filter. CONSTITUTION: An apparatus for controlling an auto gain includes an I-side AGC amplifier(12) , a filter(10), a Q-side amplifier(13), an AGC detector(14,17) and a control signal selection unit(26). The I-side AGC amplifier(12) amplifies the input signal. The filter(10) limits the bandwidth of the output signal of the I-side AGC amplifier(12) . The Q-side amplifier(13) outputs the output signal of the filter(10) with amplifying it. The AGC detector(14) generates the control signal to control the output signal of the I-side AGC amplifier(12) to a predetermined level. The AGC detector(17) generates the control signal to control the output signal of the Q-side amplifier(13) to a predetermined level and to output the control signal to the Q-side amplifier(13). And, the control signal selection unit(26) selects any one of control signals outputted from the AGC detector(14) and the AGC detector(17) to output the selected signal to the I-side AGC amplifier(12) .
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