Sigma-delta analog/digital converter with adaptive dither
AssigneeSTMicroelectronics S.r.l.
InventorsGabriele Gandolfi, Vittorio Colonna, Paolo Cusinato
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Abstract
An analog/digital ΣΔ converter has an input fed with an analog input signal, an output producing a digital signal representative of the analog input signal and a circuit for generating a dithering signal of amplitude adaptively regulated depending on the amplitude of the analog input signal. A comparator performs the regulation and uses a white noise dithering signal that is digitally generated and thereafter converted into an analog white noise dithering signal subjected to a second order filtering.
Claims13
A sigma-delta (ΣΔ) analog/digital converter with adaptive dither comprising:
- an analog-to-digital modulator for generating a digital signal based upon an analog input signal;
- a comparator for detecting an amplitude of the analog input signal;
- and
- a dithering circuit for generating and injecting a dithering signal to the analog-to-digital modulator, the dithering signal having an amplitude adaptively regulated as a function of the amplitude of the analog input signal detected by the comparator, the dithering signal having a spectrum similar to white noise, said dithering circuit comprising
- a digital generator for generating a digital white noise signal,
- at least one digital divider connected to an output of the digital generator for dividing the digital white noise signal,
- a path selector having an input connected to the output of the digital generator, at least a second input connected to an output of the digital divider, and a selection input connected to an output of the comparator,
- a digital/analog converter connected to the path selector, and
- a filter, of at least a second-order, for filtering the dithering signal.
A sigma-delta (ΣΔ) analog/digital converter comprising:
- an analog-to-digital modulator for receiving an analog input signal and generating a digital signal based thereon;
- a comparator for detecting an amplitude of the analog input signal;
- and
- a dithering circuit generating and providing a dithering signal to the analog-to-digital modulator, said dithering circuit comprising
- a digital generator for generating a digital white noise signal,
- at least one digital divider connected to an output of the digital generator for dividing the digital white noise signal,
- a path selector having at least a first input connected to the output of the digital generator, a second input connected to an output of the at least one digital divider, and a selection input connected to an output of the comparator,
- a digital/analog converter connected to the path selector for outputting the dithering signal to the analog-to-digital converter, the dithering signal having an amplitude adaptively regulated as a function of the amplitude of the analog input signal detected by the comparator, and
- a filter for filtering the dithering signal.
A method of performing a sigma-delta (ΣΔ) analog/digital conversion of an analog input signal, the method comprising:
- detecting an amplitude of the analog input signal;
- generating a digital white noise signal;
- dividing the digital white noise signal to generate a divided digital white noise signal;
- selecting, based upon the detected amplitude of the analog input signal, at least one of the digital white noise signal and the divided digital white noise signal as the dithering signal;
- filtering and performing a digital-to-analog conversion of the dithering signal;
- and
- converting the analog input signal to a digital signal based upon the dithering signal.
Dependencies are inferred from the claim text.