Capacitive field sensor with sigma-delta modulator
AssigneeCypress Semiconductor Corporation
InventorsViktor Kremin, Andriy Ryshtun
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Abstract
A capacitive sensor includes a switching capacitor circuit, a comparator, and a charge dissipation circuit. The switching capacitor circuit reciprocally couples a sensing capacitor in series with a modulation capacitor during a first switching phase and discharges the sensing capacitor during a second switching phase. The comparator is coupled to compare a voltage potential on the modulation capacitor to a reference and to generate a modulation signal in response. The charge dissipation circuit is coupled to the modulation capacitor to selectively discharge the modulation capacitor in response to the modulation signal.
Claims7
A method of operating a capacitive sensor, the method comprising:
- charging first and second series coupled capacitors during a first operation phase;
- discharging the first capacitor while holding charge on the second capacitor during a second operation phase;
- comparing a voltage potential on the second capacitor to a reference;
- and
- selectively discharging the second capacitor in response to the comparing.
Dependencies are inferred from the claim text.