Method and apparatus for analog to digital conversion of small signals in the presence of a large DC offset
AssigneeAnalog Devices, Inc.
InventorRoberto Maurino
Life of this patent
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Abstract
Embodiments of the present invention provide a hybrid analog to digital converter that may include a DAC coupled to a hybrid analog to digital converter input; an integrator having an input coupled to the hybrid analog to digital converter input and the DAC, and generating an integrator output; a comparator coupled to the integrator output and having a comparator output; a successive approximation register coupled to the comparator output; and a counter coupled to the comparator output to generate an hybrid analog to digital converter output. The hybrid analog to digital converter may be operable as a successive approximation register converter and a continuous time sigma delta converter.
Claims20
A hybrid analog to digital converter, comprising:
- a DAC having a terminal for a signal to be converted;
- an integrator having an input coupled to a hybrid analog to digital converter input and the DAC terminal, and generating an integrator output;
- a comparator coupled to the integrator output and having a comparator output;
- a successive approximation register coupled to the comparator output;
- a counter coupled to the comparator output to generate a hybrid analog to digital converter output;
- and
- a single bit DAC coupled to the integrator input, wherein the single bit DAC is controlled by the comparator during a sigma delta converter operation.
A method of converting an analog signal into a digital signal while removing a DC offset, comprising:
- in a coarse calibration phase, performing successive approximation register bit trials to calculate a coarse calibration value of the DC offset;
- in a fine calibration phase, performing incremental continuous time sigma delta conversion to calculate a fine calibration value of the DC offset using the coarse calibration value of the DC offset;
- and
- in a normal operation phase, converting an input analog signal into a digital signal and removing the DC offset using both the coarse calibration value and fine calibration value of the DC offset.
An apparatus comprising:
- a sensor to receive an information signal and convert the information signal to an AC signal;
- and
- a hybrid converter to receive the AC signal, convert the AC signal into a digital signal, and remove a DC offset, comprising:
- a DAC;
- an integrator having an input coupled to the DAC;
- a comparator coupled to the integrator;
- a successive approximation register coupled to the comparator;
- and
- a counter coupled to the comparator,
- wherein the hybrid converter is operable as a successive approximation register converter and a continuous time sigma delta converter.
Dependencies are inferred from the claim text.