Capacitive field sensor with sigma-delta modulator
First Claim
Patent Images
1. A capacitive sensor, comprising:
- a switching capacitor circuit to reciprocally couple a sensing capacitor in series with a modulation capacitor during a first switching phase and to discharge the sensing capacitor during a second switching phase;
a comparator coupled to compare a voltage potential on the modulation capacitor to a reference and to generate a modulation signal in response; and
a charge dissipation circuit coupled to the modulation capacitor to selectively discharge the modulation capacitor in response to the modulation signal.
6 Assignments
0 Petitions
Accused Products
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.
135 Citations
17 Claims
-
1. A capacitive sensor, comprising:
-
a switching capacitor circuit to reciprocally couple a sensing capacitor in series with a modulation capacitor during a first switching phase and to discharge the sensing capacitor during a second switching phase; a comparator coupled to compare a voltage potential on the modulation capacitor to a reference and to generate a modulation signal in response; and a charge dissipation circuit coupled to the modulation capacitor to selectively discharge the modulation capacitor in response to the modulation signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A system for implementing a user interface, comprising:
-
a switching capacitor circuit to reciprocally couple a field capacitor of the user interface in series with a modulation capacitor during a first switching phase and to discharge the field capacitor during a second switching phase; a modulation circuit coupled to compare a voltage potential on the modulation capacitor to a reference and to generate a feedback signal to control selective discharge of the modulation capacitor; and a measurement circuit coupled to measure a duty cycle of the feedback signal. - View Dependent Claims (13, 14, 15, 16, 17)
-
Specification