| 摘要 |
A digital automatic gain control (AGC) circuit in a digital communication receiver generates a gain adjusted output signal (104) having nominally constant output power by controllably attenuating an input signal (101). Attenuation is accomplished by employing a coarse analog attenuator (106, 107) and a fine digital attenuator (108) under control of a digital control circuit (60). Attenuation adjustments to the analog attenuator (106, 107) alone perturb the gain adjusted output signal (104) causing processing errors in the digital receiver. The digital attenuator (108) is controllably adjusted, in a predetermined manner, to minimize the number of subsequent adjustments made to the analog attenuator (106, 107) following a first adjustment. Adjusting the digital attenuator to a prescribed intermediate attenuation setting (GO) between predetermined maximum and minimum attenuation settings (THI,TLO) for the digital attenuator (108) counteracts the effect of a simultaneous attenuation adjustment to the analog attenuator (106, 107) and also substantially reduces the likelihood of subsequent analog attenuator adjustments. This minimizes perturbations in the gain adjusted output signal (104) and processing errors in the digital receiver.
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