AUTOMATIC GAIN CONTROL APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an automatic gain control apparatus capable of coping with complicated electric field variations due to an on-vehicle environment without increasing a circuit scale. SOLUTION: The automatic gain control apparatus is provided with: an amplitude detection section 11 for obtaining an amplitude of a baseband signal on the basis of I axis and Q axis components of the baseband signal; an averaging filter 12 for averaging the amplitude value to calculate an average amplitude; an error detection section 13 for detecting an error between a desired amplitude and the average amplitude and providing an output of a gain adjustment signal S1 depending on the error; an IF gain control section 16 for setting a voltage applied to a variable amplifier 3f on the basis of the gain adjustment signal S1 to apply gain control to the variable amplifier 3f; and an RF gain control section 17 for setting a voltage applied to an LNA 3b on the basis of the gain adjustment signal S1 to carry out the gain control of the LNA 3b. COPYRIGHT: (C)2005,JPO&NCIPI