Sigma-delta ADC with dither
AssigneeMediatek Inc.
InventorsFrank Op 't Eynde, Chi-Lun Lo, Michael A. Ashburn
Life of this patent
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Abstract
Systems and methods for reducing spurious noise tones in sigma-delta analog-to-digital converters (ADCs) are described. A dither signal may be added to two differential input signals of a pseudo-differential sigma-delta ADC. The dither signal may be generated by a pseudo-random bit sequence generator and applied to two input buffers, which add the dither signal to received differential analog input signals. The dithered signals may be digitized by two independent sigma-delta ADCs and then subtracted to remove the dither signal from an overall digital output signal.
Claims20
A differential analog-to-digital converter (ADC) comprising:
- a differential analog input comprising a first signal input terminal and a second signal input terminal;
- a first ADC connected to the first signal input terminal in a first signal path;
- a second ADC connected to the second signal input terminal in a second signal path;
- a dither input terminal configured to receive a dither signal;
- and
- a filter configured to filter the dither signal, wherein an output from the filter is coupled to both the first and second signal paths so that the output from the filter dithers output signals from the first ADC and second ADC.
A method for converting analog to digital signals, the method comprising:
- receiving, at a first input terminal, a first analog signal;
- receiving, at a second input terminal, a second analog signal;
- applying essentially a same amount of dither to the first analog signal and the second analog signal to produce a first dithered analog signal and second dithered analog signal;
- applying the first dithered analog signal to a first ADC;
- applying the second dithered analog signal to a second ADC;
- and
- differencing output signals from the first ADC and the second ADC.
Dependencies are inferred from the claim text.