Patent ID: 6289044
Filing Date: 2001-09-11
Classification: H03G

Abstract:
An automatic gain control circuit for a modem receiver, said receiver having an analog automatic gain control (AGC) amplifier to attenuate an input signal X prior to being digitized to a signal Y by an analog-to-digital converter, said automatic gain control circuit comprising:(a) means for obtaining an AGC signal from the signal Y;(b) means for subtracting the AGC signal from a prescribed reference signal to form a delta signal;(c) scaling means for reducing the delta signal by a prescribed value including a programmable loop gain characterized by 2.sup.-k.sup..sub.1 , wherein k.sub.1 represents a gain factor;(d) an up/down counter with variable step size for integrating the scaled delta signal to form an AGC level control signal; and(e) an analog reconstruction filter for converting the AGC level control signal to an analog AGC control signal for the analog AGC amplifier to attenuate the input signal X.