AUTOMATIC GAIN CONTROL CIRCUIT OF RECEIVING DEVICE FOR TRAVELING OBJECT, AMPLIFIER CIRCUIT WITH AUTOMATIC GAIN CONTROL CIRCUIT, INTEGRATED CIRCUIT, AND METHOD FOR AUTOMATIC GAIN CONTROL OF RECEIVING DEVICE FOR TRAVELING OBJECT

摘要

PROBLEM TO BE SOLVED: To prevent distortion of an output signal and interference in a receiving device.;SOLUTION: The intensity of a detected received signal is compared with a 1st threshold voltage and 2nd threshold voltage larger than the 1st threshold voltage, and a control signal for adjusting the gain of a variable amplifier VGA to the intensity of the received signal is outputted to the variable amplifier so that the gain has a hysteresis characteristic. A gain G1 and a gain G2 larger than the gain G1 is made to correspond to the 1st threshold voltage and a gain G3 and a gain G4 larger than the gain G3 is made to correspond to the 2nd threshold voltage; when the intensity of the detected received signal increases from below the 1st threshold voltage to the 2nd threshold voltage, a control signal is outputted to the variable amplifier so that the gain increases to thr gain G4 through the gain G2 or when the intensity of the detected received signal decreases from above the 2nd threshold voltage to the 1st threshold voltage, a control signal is outputted to the variable amplifier so that the gain decreases to the gain G1 through the gain G3.;COPYRIGHT: (C)2005,JPO&NCIPI