Patent ID: 7116955

Claim:
An automatic gain control (AGC) circuit comprising: an AGC loop including a first variable gain amplifier (VGA) and a second VGA; and control circuitry for controlling respective amounts of gain applied by the first and second VGAs, the control circuitry comprising: a first power monitor circuit, coupled to the first VGA for providing a first power level signal representing an average power level of an output signal of the first VGA; a second power monitor circuit, coupled to the second VGA for providing a second power level signal representing an average power level of an output signal of the second VGA; difference circuitry which generates first and second error signals representing respective differences between the first and second power level signals and first and second target signals, representing desired power levels for the output signals of the first and second VGAs respectively, and a combining circuit, responsive to the first and second error signals, which adjusts a total gain to be applied by the first and second VGAs and which determines a portion of the total gain to be applied by the first VGA and a portion of the total gain to be applied by the second VGA and distributes the total gain between the first and second VGAs in accordance with the determination; wherein the control circuitry is responsive to an output signal of the AGC circuit to transfer gain from the second VGA to the first VGA to reduce a noise figure of the AGC circuit while maintaining the total gain.