Methods and systems for detecting a capacitance using sigma-delta measurement techniques
First Claim
1. A method for measuring a measurable capacitance, the method comprising the steps of:
- applying a voltage to the measurable capacitance using a first switch;
allowing the measurable capacitance to share charge with a passive network;
changing a charge on the passive network by a quantized amount of charge if the charge on the passive network is past a threshold of a quantizer, the quantized amount of charge determined at least in part as a function of a quantized value outputted by the quantizer; and
repeating each of the applying step, the allowing step, and the changing step at least once.
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Abstract
Methods, systems and devices are described for detecting a measurable capacitance using sigma-delta measurement techniques. According to various embodiments, a voltage is applied to the measurable capacitance using a first switch. The measurable capacitance is allowed to share charge with a passive network. If the charge on the passive network is past a threshold value, then the charge on the passive network is changed by a known amount for a sufficient number of repetitions until the measurable capacitance can be detected. Such a detection scheme may be readily implemented using conventional components, and can be particularly useful in sensing the position of a finger, stylus or other object with respect to a button, slider, touchpad or other input sensor.
144 Citations
49 Claims
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1. A method for measuring a measurable capacitance, the method comprising the steps of:
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applying a voltage to the measurable capacitance using a first switch; allowing the measurable capacitance to share charge with a passive network; changing a charge on the passive network by a quantized amount of charge if the charge on the passive network is past a threshold of a quantizer, the quantized amount of charge determined at least in part as a function of a quantized value outputted by the quantizer; and repeating each of the applying step, the allowing step, and the changing step at least once. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for measuring a capacitance value, the method comprising the steps of:
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applying a voltage to a first capacitance using a first switch; allowing the first capacitance to share charge with a passive network; measuring a network voltage on the passive network using a threshold voltage of a quantizer; changing a charge on the passive network by a quantized amount of charge using a charge transfer circuit responsive to the network voltage on the passive network being past the threshold voltage of the quantizer, the quantized amount of charge determined at least in part as a function of a quantized value outputted by the quantizer; and repeating each of the applying step, the allowing step, the measuring step, and the changing step at least once. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A method for measuring a plurality of measurable capacitances in a proximity sensor device, the method comprising the steps of:
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selecting a measurable capacitance in the plurality of measurable capacitances, and for the selected measurable capacitance; applying a predetermined voltage to the selected measurable capacitance using a corresponding digital output; allowing the selected measurable capacitance to share charge with a passive network, the passive network comprising at least one integrating capacitor; comparing a voltage on the passive network to a threshold voltage and generating a quantized value responsive to the measuring; changing a charge on the passive network by a quantized amount of charge based on the quantized value; repeating each of the applying step, the allowing step, the comparing step, and the changing step at least once for the selected measurable capacitance; and determining a value of the selected measurable capacitance by digitally filtering quantized values generated responsive to repetitions of the comparing step; and performing each of the applying step, the allowing step, the comparing step, the changing step, the repeating step and the determining step for at least one additional selected measurable capacitance in the plurality of measurable capacitances. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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Specification