CAPACITANCE SENSING CIRCUIT AND POWER SUPPLYING APPARATUS UTILIZING THE CAPACITANCE SENSING CIRCUIT

摘要

A capacitance sensing circuit, comprising: a first voltage source; a first switch, wherein the first voltage source charges a sensing capacitor to a first voltage when the first switch is conductive; a base capacitor; a second voltage source; a second switch, wherein the second voltage source charges the base capacitor to a second voltage when the second switch is conductive, where the first switch and the second switch are simultaneously conductive via a control signal; a first comparator, for outputting a first comparing result according to a voltage difference between a sensing voltage on the sensing capacitor and a base voltage on the base capacitor, and a voltage difference between the first voltage and the second voltage; and a voltage holding circuit, for keeping the base voltage at a reference voltage.

主权项

1. A capacitance sensing circuit, comprising:
a first voltage source; a first switch, wherein the first voltage source charges an sensing capacitor to a first voltage when the first switch is conductive; a base capacitor; a second voltage source; a second switch, wherein the second voltage source charges the base capacitor to a second voltage when the second switch is conductive; a first comparator, for outputting a first comparing result according a difference between a first voltage difference and a second voltage difference, wherein the first voltage difference is a difference for the first voltage and the second voltage, wherein the second voltage difference is a difference for an sensing voltage on the sensing capacitor and a base voltage on the base capacitor; and a voltage holding circuit, for keeping the base voltage at a reference voltage.