Low-power activation circuit with motion detector
First Claim
1. A circuit, comprising:
- a sensor element configured to output a sensor output signal corresponding to a sensed quantity to a digital difference detection circuit;
wherein the digital difference detection circuit comprises;
a digital measurement element configured to track the sensor output signal and generate a digital signal therefrom;
a digital storage element configured to store one or more previous digital signals corresponding to the sensor output signal generated over time;
a difference detector configured to detect a difference between a current digital signal and at least one of the one or more previous digital signals, wherein if the difference is larger than a digital reference level, the difference detector causes an activation signal generator to generate an activation signal that awakens a system from a sleep mode or a low-power mode; and
one or more switches connected between the sensor element and the digital measurement element upstream of the difference detector.
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Abstract
The present disclosure relates to a method and apparatus to perform a low power activation of a system. In one embodiment, the apparatus includes a sensor element configured to output a sensor output signal corresponding to a sensed quantity to a digital difference detection circuit. The digital difference detection circuit has a digital measurement element configured to track the sensor output signal and generate a digital signal therefrom, a digital storage element configured to store previous digital signals corresponding to the sensor output signal generated over time, and a difference detector configured to detect a difference between a current digital signal and at least one of the previous digital signals. If the difference is larger than a digital reference level, the difference detector causes an activation signal generator to generate an activation signal that awakens a system from a sleep mode or a low-power mode.
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Citations
20 Claims
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1. A circuit, comprising:
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a sensor element configured to output a sensor output signal corresponding to a sensed quantity to a digital difference detection circuit; wherein the digital difference detection circuit comprises; a digital measurement element configured to track the sensor output signal and generate a digital signal therefrom; a digital storage element configured to store one or more previous digital signals corresponding to the sensor output signal generated over time; a difference detector configured to detect a difference between a current digital signal and at least one of the one or more previous digital signals, wherein if the difference is larger than a digital reference level, the difference detector causes an activation signal generator to generate an activation signal that awakens a system from a sleep mode or a low-power mode; and one or more switches connected between the sensor element and the digital measurement element upstream of the difference detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A circuit, comprising:
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a sensor element configured to output a sensor output signal; a digital measurement element configured to generate a current digital signal from the sensor output signal; a digital storage element configured to store a previous digital signal corresponding to the sensor output signal at a past time; a difference detector configured to detect a difference between the current digital signal and the previous digital signal, wherein the digital measurement element is coupled between the sensor element and the difference detector; an offset compensation circuit located between the digital measurement element and the difference detector, and configured to remove an offset of the sensor output signal to generate a first offset compensated signal that the difference detector is configured to compare with the previous digital signal; and wherein the difference detector is configured to cause an activation signal generator to generate an activation signal that awakens a system from a sleep mode or a low-power mode if a value of the difference or a time period over which the difference changes violates a reference level. - View Dependent Claims (11, 12, 13, 14)
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15. A method for activating a system from a sleep mode, comprising:
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generating a digital signal proportional to a measured sensor signal representing a measured quantity; detecting a difference between a current digital signal and a previous digital signal stored in a digital storage element, wherein the detected difference has a value that is based on a change in magnitude between the current digital signal and the previous digital signal and on a change between times at which the current digital signal and the previous digital signal were generated; and comparing the detected difference to a digital reference level, wherein if the difference is larger than the digital reference level an activation signal is output. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification