APPARATUS AND METHOD FOR GAIN CONTROL IN BROADBAND RECEIVER

摘要

A gain control apparatus of a broadband receiver and a gain controlling method thereof are provided to enhance the reliability of the broadband receiver by minimizing generation of IM3(Third order Intermodulation). An attenuator(31) attenuates a signal received by a broadband receiver. A LAN(Low Noise Amplifier)(32) amplifies an output of the attenuator. An RF variable gain amplifier(34) amplifies an output of the LAN at an RF terminal. A local oscillator(35) outputs a local oscillation frequency. A PLL(Phase-Locked Loop)(36) maintains constantly a frequency of an output signal of the local oscillator. A first mixer(37) couples the output of the LNA and an output of the local oscillator with each other. A second mixer(38) couples an output of the RF variable gain amplifier and the output of the local oscillator with each other. An IF variable gain amplifier(39) amplifies an output of the second mixer at an IF terminal. A first controller(41) measures an RSSI(Received Signal Strength Indicator) from the output of the first mixer and controls the attenuator. A second controller(42) measures the RSSI from the output of the second mixer and controls the RF variable gain amplifier. A third controller(43) measures the RSSI from the output of the IF variable gain amplifier and controls the IF variable gain amplifier.