Patent ID: 6538507
Filing Date: 2003-03-25
Classification: H03F,H03G

Abstract:
An automatic gain control (AGC) circuit, comprising:a high gain amplifier having an input and an output, the output asserting an output signal of the AGC circuit; a feedback network having a first end receiving an input signal of the AGC circuit, a second end coupled to the output of the high gain amplifier and first and second intermediate nodes; and first and second transconductance amplifiers, each having an input coupled to a respective one of the first and second intermediate nodes of the feedback network and an output coupled to the input of the high gain amplifier, the first and second transconductance amplifiers collectively controlling a position of a virtual ground within the feedback network to control gain of the AGC circuit, each of the first and second transconductance amplifiers comprising: an attenuator coupled to the feedback network; and a transconductance stage coupled to the attenuator and to the input of the high gain amplifier, each transconductance amplifier operating linearly across a relatively wide input voltage range.