Sensing circuits
AssigneeCirrus Logic International Semiconductor Ltd.
InventorJohn Paul LESSO
Life of this patent
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Abstract
This application relates to sensing circuits for sensing a physical property or quantity of interest. The sensing circuit has an oscillator comprising a hysteretic comparator and a loop filter configured to output an oscillation signal. The loop filter comprises a first component with an electrical property that varies with the physical property or quantity of interest. A time constant of the loop filter depends on the electrical property of the first component. A decoder is configured to receive the oscillation signal and provide an indication of any change in frequency of the oscillation signal as an indication of a change in the physical property or quantity of interest. The electrical property may be an impedance, such as a resistance.
Claims20
A sensing circuit for monitoring a physical property or quantity of interest comprising:
- an oscillator comprising a hysteretic comparator and a loop filter configured to output an oscillation signal;
- wherein the loop filter comprises a first component with an electrical property that varies with said physical property or quantity;
- wherein a time constant of the loop filter depends on the electrical property of the first component;
- and
- a decoder configured to receive the oscillation signal and provide an indication of any change in frequency of the oscillation signal.
A sensing circuit comprising:
- an oscillator comprising a hysteretic comparator and a loop filter configured to output an oscillation signal;
- wherein the loop filter comprises a first component with an impedance that varies in response to an external stimulus, wherein a time constant of the loop filter depends on the electrical property of the first component;
- and
- a decoder configured to receive the oscillation signal and provide an indication of frequency of the oscillation signal.
A sensor for sensing a physical property or quantity of interest comprising:
- an oscillator comprising a comparator and a loop filter configured to output an oscillation signal;
- wherein the loop filter comprises a first component with an electrical property that varies with said physical property or quantity of interest, wherein a time constant of the loop filter depends on the electrical property of the first component;
- and
- a decoder configured to receive the oscillation signal and a first clock signal and provide a count value as an indication of a frequency of the oscillation signal;
- wherein the oscillator comprises a timing controller for controlling at least one timing parameter of the oscillation signal based on the first clock signal and/or the indication of the frequency of the oscillation signal.
Dependencies are inferred from the claim text.