Fast automatic gain control circuit and method for zero intermediate frequency receivers and radiotelephone using same

摘要

A method and apparatus provides control of the gain of an input amplifier (306) in a radio receiver (300), such as in a radiotelephone handset (104). The radio receiver (300) includes an automatic gain control circuit (318). The automatic gain control circuit (318) includes a timer circuit (370) which provides asynchronous, digital automatic gain control circuit to perform a coarse gain adjustment. The automatic gain control circuit (318) further includes an integrator (366) which provides analog automatic gain control for providing remaining needed gain regulation. The automatic gain control circuit (318) provides substantial reduction in input signal acquisition time for the radio receiver (300).