Automatic gain control with analog and digital gain
AssigneeLSI Logic Corporation
InventorsBradley J. Burke, Dean Raby
Life of this patent
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Abstract
An automatic gain control system combining both analog and digital gain units, both controlled by a common digital control system. The overall system gain settings are selected by a combination of analog gain settings and digital gain settings. The number of analog gain settings is less than the total number of system gain settings, so that the board or chip area required for the analog gain settings is reduced, while sufficient range is provided to maintain a good signal to noise ratio from an A/D converter. When a required gain adjustment exceeds one step of the analog gain stage, the system simultaneously adjusts the analog gain and the digital gain unit to provide a smooth transition.
Claims13
An automatic gain control system providing a first plurality of gain settings, comprising:
- an analog gain device having a second plurality of gain settings, said second plurality being less than said first plurality;
- a digital gain device;
- a controller coupled to said analog gain device and to said digital gain device, comparing a signal level from the analog gain device to a desired signal level, and adjusting the gain of the analog gain device and the digital gain device to provide the desired signal level at an output.
A method for providing automatic gain control having a first plurality of gain settings for a signal, comprising:
- using an adjustable gain analog amplifier to amplify an analog signal, said amplifier having a second plurality of gain settings, said second plurality being less than said first plurality;
- digitizing the output of said analog amplifier to provide a digitized signal, and
- using an adjustable gain digital gain unit to adjust the amplitude of said digitized signal.
A method for providing automatic gain control having a first plurality of gain settings for a signal, comprising:
- using an adjustable gain analog amplifier to amplify an analog signal, said amplifier having a second plurality of gain settings, said second plurality being less than said first plurality;
- digitizing the output of said analog amplifier to provide a digitized signal,
- using an adjustable gain digital gain unit to adjust the amplitude of said digitized signal;
- measuring the amplitude of the amplified analog signal;
- determining which setting of said first plurality of gain settings is required to change said amplitude of the amplified analog signal to a desired amplitude;
- and
- setting the gain of said adjustable gain analog amplifier and said adjustable gain digital gain unit to change said amplitude of the amplified analog signal to said desired amplitude.
Dependencies are inferred from the claim text.