Capacitance to code converter with sigma-delta modulator
First Claim
1. An apparatus comprising:
- a modulator comprising a modulator capacitor;
a capacitor comprising a first plate and a second plate;
a switching circuit comprising;
a first switch coupled between a voltage source and the first plate of the capacitor;
a second switch coupled between the second plate of the capacitor and the voltage source; and
a third switch coupled between the first plate of the capacitor and a ground node,wherein the capacitor is to provide a charge current to the modulator capacitor, and wherein the modulator is to measure a capacitance of the capacitor and convert the capacitance to a digital code representing the capacitance, wherein;
in a first configuration, the first switch is closed to connect the voltage source to the first plate of the capacitor and the second switch is open to disconnect the voltage source from the second plate of the capacitor, andin a second configuration, the first switch is open to disconnect the voltage source from the first plate of the capacitor and the second switch is closed to connect the voltage source to the second plate of the capacitor.
5 Assignments
0 Petitions
Accused Products
Abstract
Apparatuses and methods of converting a capacitance measured on a sense element to a digital value are described. One apparatus includes a modulator having a modulator capacitor, a sense element selectively coupled in a feedback loop of the modulator to operate as a switching capacitor. The apparatus also includes a first switch coupled between a voltage source and a first node of the switching capacitor and a second switch coupled between the first node of the switching capacitor and a first node of the modulator capacitor. The switching capacitor provides a charge current to the modulator capacitor via the second switch. The modulator measures a capacitance of the sense element and converts the measured capacitance to a digital code representing the capacitance.
14 Citations
19 Claims
-
1. An apparatus comprising:
-
a modulator comprising a modulator capacitor; a capacitor comprising a first plate and a second plate; a switching circuit comprising; a first switch coupled between a voltage source and the first plate of the capacitor; a second switch coupled between the second plate of the capacitor and the voltage source; and a third switch coupled between the first plate of the capacitor and a ground node, wherein the capacitor is to provide a charge current to the modulator capacitor, and wherein the modulator is to measure a capacitance of the capacitor and convert the capacitance to a digital code representing the capacitance, wherein; in a first configuration, the first switch is closed to connect the voltage source to the first plate of the capacitor and the second switch is open to disconnect the voltage source from the second plate of the capacitor, and in a second configuration, the first switch is open to disconnect the voltage source from the first plate of the capacitor and the second switch is closed to connect the voltage source to the second plate of the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method comprising:
-
operating a switching circuit in a first configuration, the switching circuit comprising a first switch, a second switch, and a third switch; measuring, by a modulator, a first capacitance of a capacitor comprising a first plate and a second plate, wherein, in the first configuration, the first switch is closed to connect a voltage source to the first plate of the capacitor and the second switch is open to disconnect the voltage source from the second plate of the capacitor, operating the switching circuit in a second configuration; measuring, by the modulator, a second capacitance of the capacitor, wherein, in the second configuration, the first switch is open to disconnect the voltage source from the first plate of the capacitor and the second switch is closed to connect the voltage source to the second plate of the capacitor; and converting the first capacitance to a first digital value and converting the second capacitance to a second digital value. - View Dependent Claims (14, 15, 16)
-
-
17. An apparatus comprising:
-
a capacitor comprising a first plate and a second plate; a switching circuit coupled to a voltage source, the switching circuit comprising; a first switch coupled between the voltage source and the first plate of the capacitor; a second switch coupled between the second plate of the capacitor and the voltage source; and a third switch coupled between the first plate of the capacitor and a ground node, wherein, in a first configuration, the first switch is closed to connect the voltage source to the first plate of the capacitor and the second switch is open to disconnect the voltage source from the second plate of the capacitor, and wherein, in a second configuration, the first switch is open to disconnect the voltage source from the first plate of the capacitor and the second switch is closed to connect the voltage source to the second plate of the capacitor; and a measurement circuit coupled to the switching circuit to measure a first capacitance of the capacitor while the switching circuit is in the first configuration and to measure a second capacitance of the capacitor while the switching circuit is in the second configuration, and to convert the first capacitance to a first digital code and the second capacitance to a second digital code. - View Dependent Claims (18, 19)
-
Specification