| 摘要 |
PURPOSE: A receiver for a mobile communication system is provided to output a signal with an excellent receipt sensitivity by uniformly maintaining a gain of a front end portion. CONSTITUTION: A gain adjusting unit(202) adjusts a gain of a received RF signal so that the RF signal has a uniform gain. A frequency converting unit(203) converts the RF signal outputted from the gain adjusting unit(202) into the first signal(I) and the second signal(Q) of a baseband with an inter-different phase. Low pass filters(47a,47b,49a,49b,51a,51b) output the first signal(I) and the second signal(Q) outputted from the frequency converting unit(203). Voltage control amplifiers(48a,48b,50a,50b) adjust levels of the first signal(I) and the second signal(Q) outputted from the low pass filters(47a,47b,49a,49b,51a,51b) according to a control signal provided from the outside. Detectors(52a,52b) detects the first signal(I) and the second signal(Q) outputted from the voltage control amplifiers(48a,48b,50a,50b). An automatic gain control circuit(54) analyzes the detected first signal(I) and second signal(Q) and provides the control signal to the voltage control amplifiers(48a,48b,50a,50b). A control circuit unit(205) compares signals outputted from the low pass filters(47a,47b,49a,49b,51a,51b) with level values of the RF signal received in the gain adjusting unit(202) and provides a control signal to the gain adjusting unit(202) so that the difference of the level values is a reference value provided from the outside.
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