Patent ID: 6473182
Filing Date: 2002-10-29
Classification: H03G

Abstract:
A closed loop gain control circuit for controlling the gain of a non-linear variable gain amplifier that is arranged to amplify signals output from a signal source, comprising:a perturbation source arranged to provide dither signals of magnitude Â±d; a modulator connected between the perturbation source and the signal source; a dither compensation circuit connected to the amplifier and arranged to apply dither compensation signals having magnitude Â±rd to signals output from the amplifier, the dither compensation signals being formed to reduce the magnitude of the dither in the signals output from the amplifier; a gain error demodulator connected to receive signals output from the dither compensation circuit, the gain error demodulator being arranged to provide a gain error signal that indicates the magnitude of the dither in the signals output from the analog to digital converter; and a feedback system connected to the gain control demodulator and arranged to provide a gain control signal to the variable gain amplifier to reduce the magnitude of the gain error signal.