Automatic gain control circuit and receiver device having the automatic gain control circuit, and automatic gain control method

Abstract

An automatic gain control circuit optimizes a follow-up performance of an automatic gain control loop to thus assure a good receiving operation. A generation timing or a generation period of a control signal GC is decided in response to a lapsed time in operation of the receiver device. For a predetermined rise period from a non-operated state to the steady operation state when a power supply is shifted from its OFF state to its ON state (power supply is turned ON) or at the time of intermittent receiving operation, the generation period of the control signal GC is set shorter than the generation period in a steady operation state so as to accelerate the response characteristic of the automatic gain control gain rather than the steady operation condition, and then switched to the generation period in the steady operation state after a predetermined time.

1 . An automatic gain control circuit comprising: 
 a gain variable amplifier which controls an amplitude of a receiving signal based on a control signal;    control signal generating means for level-detecting the receiving signal and then generating a feedback signal as the control signal for the gain variable amplifier; and    controlling means for deciding at least one of a generation timing of the control signal and a generation period of the control signal in response to a predetermined physical quantity, and controlling the control signal generating means.    
   
   
       2 . An automatic gain control circuit according to  claim 1 , further comprising: 
 detected output change amount detecting means for detecting an amount of change in a detected output of the receiving signal;    wherein the controlling means decides the generation timing of the control signal or the generation period of the control signal using an amount of change in the detected output as the predetermined physical quantity.    
   
   
       3 . A receiver device comprising: 
 an automatic gain control circuit including: a gain variable amplifier which controls an amplitude of a receiving signal based on a control signal; control signal generating means for level-detecting the receiving signal and then generating a feedback signal as the control signal for the gain variable amplifier; and controlling means for deciding at least one of a generation timing of the control signal and a generation period of the control signal in response to a predetermined physical quantity, and controlling the control signal generating means.    
   
   
       4 . An automatic gain control method in a receiver device including a gain variable amplifier which controls an amplitude of a receiving signal based on a control signal, the method comprising: 
 a control signal generating step of level-detecting the receiving signal and then generating a feedback signal as the control signal for the gain variable amplifier; and    a controlling step of deciding a generation timing of the control signal or a generation period of the control signal in response to a predetermined physical quantity.    
   
   
       5 . An automatic gain control method in a receiver device according to  claim 4 , further comprising: 
 a detected output change amount detecting step of detecting an amount of change in a detected output of the receiving signal;    wherein the controlling step decides the generation timing of the control signal or the generation period of the control signal using an amount of change in the detected output as the predetermined physical quantity.    
   
   
       6 . A computer-readable recording medium for recording the automatic gain control method for the receiver device as a program to be executed by a computer, said method comprising: 
 a control signal generating step of level-detecting the receiving signal and then generating a feedback signal as the control signal for the gain variable amplifier; and    a controlling step of deciding a generation timing of the control signal or a generation period of the control signal in response to a predetermined physical quantity.