Continuous-time ΔΣ analog-to-digital converter with duty-cycle-controlled input path
AssigneeQUALCOMM Incorporated
InventorsChieh-Yu Hsieh, Yuhua Guo, Dinesh Jagannath Alladi
Life of this patent
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Abstract
A delta-sigma analog-to-digital converter is provided that includes a continuous-time integration stage having an input terminal coupled through a switch to an input resistor that in turn couples to an input signal node. A feedback digital-to-analog converter converts a digital output signal to form a feedback current that also couples to the input terminal. A controller switches the first switch responsive to a duty cycle of the feedback current.
Claims20
A continuous-time delta-sigma analog-to-digital converter, comprising:
- an input signal node for an analog input signal;
- a continuous-time integration stage including a first input terminal;
- an input resistor coupled to the input signal node;
- a first switch coupled between the input resistor and the first input terminal;
- a return-to-zero digital-to-analog converter configured to pulse a feedback current to the first input terminal;
- and
- a controller configured to switch the first switch responsive to an integration pulse width of the feedback current;
- and
- a second switch coupled between the first input terminal and ground, wherein the controller is configured to switch on the first switch and switch off the second switch during the integration pulse width.
A continuous-time delta-sigma analog-to-digital converter, comprising:
- an input signal node for an analog input signal;
- a continuous-time integration stage including a first input terminal;
- an input resistor coupled to the input signal node;
- a first switch coupled between the input resistor and the first input terminal;
- a capacitive digital-to-analog converter configured to transiently pulse a feedback current to the first input terminal during an integration pulse width of a clock signal;
- and
- a controller configured to switch the first switch on during an off time of the clock signal and to switch the first switch off during the integration pulse width;
- a second switch coupled between the first input terminal and ground,
- wherein the controller is further configured to switch off the second switch during the off time and to switch on the second switch during the integration pulse width.
A method of digitizing an input current, comprising:
- gating an input current responsive to a duty cycle of a clock signal to form a gated input current, wherein gating the input current comprises coupling the input current to ground through an input resistor during a portion of the clock cycle;
- integrating a difference between the gated input current and a feedback current to form an integrated output signal;
- quantizing the integrated output signal to form a digital output signal;
- and
- converting the digital output signal in a digital-to-analog converter responsive to the clock signal to form the feedback current.
Dependencies are inferred from the claim text.