Automatic gain control method and device for a variable gain amplifier

Abstract

The automatic gain control method adapted to maintain the output level equal of the variable gain amplifier to a required value, includes a preliminary calibration phase for establishing a relationship representing the variations in the amplifier gain control signal as a function of variations in the input signal level with a constant output level equal to the required value or as a function of variations in the output signal level for a constant input signal level. The method further includes an operative phase for applying to the amplifier of a particular value of the gain control signal, measuring the corresponding output level, detecting any offset between the result of the measurement and the required value, and if such an offset is detected, determining a corresponding control signal value conditioned by the relationship previously established, and depending on the mode utilized to establish the relationship, either an input level whose offset relative to the corresponding input level given by the relationship at the particular value of the control signal is opposite to said detected offset, or an output level whose offset relative to the required value is opposite to the detected value, and finally, selectively updating the particular value when an offset is detected to so that the particular value becomes equal to the value obtained by the determination.