High resolution capacitance to code converter
AssigneeCypress Semiconductor Corporation
InventorsRoman Ogirko, Hans Klein, Andriy Maharyta
Life of this patent
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Abstract
An integration circuit including a first capacitor is operatively coupled to a comparator. The comparator is configured to compare a first capacitor voltage of the first capacitor to a reference voltage and produce a first comparator output based on the comparison. A current generator is operatively coupled with the integration circuit and configured to balance charge on the first capacitor. A control unit is operatively coupled to the comparator and the current generator and configured to balance charge on the first capacitor by sensing the first comparator output and controlling the current generator based on the first comparator output.
Claims21
1-20. (canceled)
A method comprising:
- coupling a first capacitor to an electrode of a capacitive sense array;
- integrating charge received from the electrode of the capacitance sense array with the first capacitor;
- decoupling the first capacitor from the electrode of the capacitive sense array;
- coupling a second capacitor to the electrode of the capacitive sense array;
- concurrently integrating charge received from the electrode of the capacitive sense array with the second capacitor and supplying a first balancing charge to the first capacitor;
- ceasing to supply the first balancing charge to the first capacitor when the charge on the first capacitor falls below a predetermined level;
- and
- calculating a first value representative of a capacitance of the electrode of the capacitive sense array based on a measure of the first balancing charge supplied to the first capacitor.
An apparatus comprising:
- a capacitive sense array comprising a plurality of electrodes;
- a first convertor and a second convertor each selectively coupled to at least one of the plurality of sensing electrodes;
- a current generator selectively coupled to the first and second convertors;
- and
- a control unit coupled to the first and second convertors, the control unit configured to control the duration for which the current generator is coupled to each of the first and second controllers to balance charge of each of the first and second controllers, wherein the first convertor is configured to sample a signal representative of the capacitance of an electrode of the capacitive sense array while the second convertor is configured to balance a previously sampled charge to allow continuous integration of the input signal.
A device comprising:
- a terminal configured to be coupled to an electrode of a capacitive sense array;
- a first capacitor and a second capacitor each configured to be selectively coupled to the terminal, and to operate as an integrator;
- a current generator configured to be selectively coupled to each of first and second capacitors;
- and
- a control unit configured to control the coupling of the first and second capacitors to the terminal and to the current generator and configured to balance charge on each of the first and second capacitors by controlling the current generator and the coupling of the current generator to each of the first and second capacitors.
Dependencies are inferred from the claim text.