RESOLUTION-BOOSTED SIGMA DELTA ANALOG-TO-DIGITAL CONVERTER
First Claim
1. An analog-to-digital converter (ADC) receiving an analog signal as input and providing an output digital value representative of the analog signal, comprising:
- a first multiplexer receiving two or more reference signals to provide a selected reference signal;
a sigma delta modulator receiving the selected reference signal and the analog signal to provide a set of pulses representative of the analog signal received;
a control circuit causing the first multiplexer to select (i) in a first phase of a conversion, a first one of the reference signals as the selected reference signal and (ii) in subsequent phases of the conversion, the other reference signals, one at a time, as the selected reference signal, such that the sigma delta modulator provides, respectively, a first set of pulses in the first phase and an additional set of pulses in each of the subsequent phases of the conversion; and
a digital filter receiving in each conversion the first set and the subsequent sets of pulses to provide the digital output value.
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Accused Products
Abstract
A method and an ADC circuit use multiple SD modulations on an analog value and apply digital post-processing of the pulse density modulation (PDM) streams from the SD modulations obtaining a higher resolution in the digital output value for a given oversampling ratio. SD ADC does not face the constraint of conversion time doubling for each additional bit of resolution. In one implementation, an SD ADC includes conversions in SD phase and a resolution-boosting phase. During SD phase, MSBs of the digital output value are generated from the sampled analog value using a first SD conversion. At the end of SD phase, the sampled analog value is reduced to “residual quantization error,” which remains in a capacitor of an integrator of SD ADC. In resolution-boosting phase, the LSBs of the digital output value are generated from residual quantization error using a second SD conversion that provides at least the LSBs.
7 Citations
13 Claims
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1. An analog-to-digital converter (ADC) receiving an analog signal as input and providing an output digital value representative of the analog signal, comprising:
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a first multiplexer receiving two or more reference signals to provide a selected reference signal; a sigma delta modulator receiving the selected reference signal and the analog signal to provide a set of pulses representative of the analog signal received; a control circuit causing the first multiplexer to select (i) in a first phase of a conversion, a first one of the reference signals as the selected reference signal and (ii) in subsequent phases of the conversion, the other reference signals, one at a time, as the selected reference signal, such that the sigma delta modulator provides, respectively, a first set of pulses in the first phase and an additional set of pulses in each of the subsequent phases of the conversion; and a digital filter receiving in each conversion the first set and the subsequent sets of pulses to provide the digital output value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for analog-to-digital conversion of an analog signal as input to provide an output digital value representative of the analog signal, comprising:
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In a first multiplexer, selecting as a selected reference signal (i) a first reference signal in a first phase of conversion, and (ii) one or more reference signals, one at a time, in subsequent phases of the conversion; providing the analog signal and the selected reference signal to a sigma delta modulator to create, respectively, a first set of pulses and an additional set of pulses in the first phase and each of the subsequent phases, respectively; and combining in a digital filter the first set and the subsequent sets of pulses to provide the output digital value. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification