Apparatus and method for combining analog and digital automatic gain control in receivers with digital signal processing

摘要

Two automatic gain control (AGC) loops are connected by a feedforward signal. An intermediate frequency (IF) filter may be located between the output of the front-end loop and the input of the back-end loop. Stability and responsiveness are improved because neither AGC loop includes a narrowband filter. The front-end loop may include an analog gain-controlled element, but the remainder of the invention may be implemented digitally. The front-end loop prevents overloading of the A/D converter that feeds the gain-controlled signal to the remainder of the invention, and the back-end loop compensates for actions taken in the front-end loop.