| 摘要 |
A method and apparatus for automatically controlling the gain of a digital radio receiving circuit in which a single set of analogue amplifiers is used as the front end to feed two separate digital back-end, demodulating circuits, and in which, for optimal performance, each of the two digital demodulating circuits require the front end analogue amplifiers to operate over a significantly different dynamic range. An automatic-gain-control selector selects one of two automatic-gain control signals to set the gain of the analogue amplifier. In addition, the automatic-gain-control selector sets a compensatory gain of a digital automatic gain control in the back-end circuit not selected, so that the unselected demodulating circuit has substantially the same input signal as if it had been selected. In this way, both demodulating circuits can process the input signal as if they were in control of the analogue amplifier. |
