Invention Grant
US09225927B2 Automatic gain control circuit 有权
自动增益控制电路

Automatic gain control circuit
Abstract:
An automatic gain control (AGC) circuit based on a cascade of a step automatic gain control unit and a second automatic gain control unit connected to adjust their gain in a synchronized manner to result in a combined impulsive gain variation. Hereby it is possible, e.g. to use a step automatic gain control unit instead of a continuous automatic gain control unit in an RF part of a TV tuner without resulting in visual artifacts—this applies both for digital and analog TV tuners. According to a preferred embodiment, the synchronization between the two automatic gain control units may be achieved by the first automatic gain control unit generating a control signal upon gain adjustment, this control signal serving to speed up a loop bandwidth controlling gain change of the second automatic gain control unit. In another embodiment, the control signal generated by the first automatic gain control unit is used to control a gain step of the second automatic gain control unit. In addition, the invention provides a tuner with an automatic gain control unit as mentioned, and a device, e.g. a TV or a hard disc recorder with such tuner.
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