Patent ID: 7433476

Claim:
An automatic gain control unit, comprising: a voltage-controlled amplifier which amplifies a VCA input signal in order to obtain a VCA output signal, with the gain of said voltage-controlled amplifier being controlled by a closed-loop control circuit, means for generating an error signal by comparing the magnitude of the VCA output signal with a predefined reference magnitude, a forward controlling element which transforms the error signal into a gain control signal for the voltage-controlled amplifier, and means for varying the control rate of the closed-loop control circuit according to the magnitude of the VCA output signal for changing the time constant of the control rate, the control rate being increased with increasing magnitude of the VCA output signal, said means for varying the control rate of the closed-loop control circuit including a multiplier element for multiplying said error signal with a scaling factor, the scaling factor being increased with increasing magnitude of the VCA output signal, and said means for varying the control rate of the closed-loop control circuit comparing said magnitude of the VCA output signal with a predefined boost offset, whereby in case said magnitude exceeds said boost offset, said scaling factor is increased in accordance with the increase of said magnitude of the VCA output signal to decrease the time constant of the control rate.