Embedded overload protection in delta-sigma analog-to-digital converters
First Claim
1. A method for providing overload protection embedded in a delta-sigma modulator, the method comprising:
- detecting an overload condition in the delta-sigma modulator using an overload detector connected to one or more nodes in the delta-sigma modulator; and
in response to detecting the overload condition, adjusting a current gain of a feedback digital-to-analog converter of the delta-sigma modulator, and adjusting a size of a resistor positioned between an output of an amplifier of a front-end of the delta-sigma modulator and a backend of the delta-sigma modulator to compensate for the detected overload condition.
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Abstract
Delta-sigma modulators do not handle overload well, and often become unstable if the input goes beyond the full-scale range of the modulator. To provide overload protection, an improved technique embeds an overload detector in the delta sigma modulator. When an overload condition is detected, coefficient(s) of the delta sigma modulator is adjusted to accommodate for the overloaded input. The improved technique advantageously allows the delta sigma modulator to handle overload gracefully without reset, and offers greater dynamic range at reduced resolution. Furthermore, the coefficient(s) of the delta sigma modulator can be adjusted in such a way to ensure the noise transfer function is not affected.
30 Citations
20 Claims
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1. A method for providing overload protection embedded in a delta-sigma modulator, the method comprising:
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detecting an overload condition in the delta-sigma modulator using an overload detector connected to one or more nodes in the delta-sigma modulator; and in response to detecting the overload condition, adjusting a current gain of a feedback digital-to-analog converter of the delta-sigma modulator, and adjusting a size of a resistor positioned between an output of an amplifier of a front-end of the delta-sigma modulator and a backend of the delta-sigma modulator to compensate for the detected overload condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for providing overload protection, said apparatus embedded in a delta-sigma modulator, the apparatus comprising:
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a overload detector connected to one or more nodes in the delta-sigma modulator for detecting an overload condition in the delta-sigma modulator; and a coefficient controller for adjusting coefficients of the delta-sigma modulator to compensate for the detected overload condition in response to detecting the overload condition, wherein the coefficients comprises;
a first coefficient of the coefficients corresponds to a current gain of a feedback digital-to-analog converter of the delta-sigma modulator, and a second coefficient corresponds to a size of a resistor between an output of an amplifier of a front-end of the delta-sigma modulator and a backend of the delta-sigma modulator. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method for providing overload protection, the method comprising:
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determining a level from different levels of overload condition of a delta-sigma modulator; changing internal coefficients of the delta-sigma modulator affecting an analog gain of a signal transfer function of the delta-sigma modulator based on a determined level of overload condition to compensate for the determined level of overload condition while keeping a noise transfer function of the delta-sigma modulator substantially unchanged; and adjusting a digital gain of a digital output of the delta-sigma modulator corresponding to the analog gain of the signal transfer function affected by the changing of the internal coefficients in accordance with a predetermined time delay of the delta-sigma modulator. - View Dependent Claims (18, 19, 20)
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Specification