Patent ID: 8030996

Claim:
A circuit for automatic level control, comprising: an amplifier, including: a variable resistance circuit that is arranged to provide a variable equivalent resistance between a first node and a second node, wherein the variable resistance circuit has a control input, and wherein the variable resistance circuit is arranged to vary the variable resistance based on a control signal provided at the control input; a first resistance circuit that is arranged to provide a first fixed equivalent resistance between a first input node and the first node, wherein the first resistance circuit is at least approximately a linear element; a second resistance circuit that is arranged to provide a second fixed equivalent resistance between the first input node and a first op amp node, wherein the second resistance circuit is at least approximately another linear element; and an op amp having at least a first input that is coupled to the first op amp node; and an automatic level control circuit that is arranged to receive an automatic level control circuit input signal, and further arranged to adjust the variable resistance circuit based, in part, on the automatic level input signal, wherein the amplifier is arranged to provide an amplifier output signal, and wherein the automatic level control circuit input signal is based, at least in part, on the amplifier output signal.