A detection circuit includes a first detection terminal, a second detection terminal, a first switch, a second switch, a first capacitor, a second capacitor and an amplifier. The first switch is coupled to the first detection terminal. The second switch is coupled to the second detection terminal. The first capacitor is coupled between the first switch and the second switch. The amplifier includes a first input terminal coupled to the second switch, a second input terminal used to receive an operation signal, and an output terminal used to output an output signal. The second capacitor is coupled between the first input terminal and the output terminal of the amplifier. The first switch and the second switch are turned on alternatively.

A charge sensitive amplifier circuit for sensor frontend comprises an input node to be connected to a sensor to receive an input charge, and an output node to be connected to a charge conversion circuit. The charge sensitive amplifier circuit comprises a first transfer switch located between the input node and the output node to transfer the input charge to the output node. The charge sensitive amplifier circuit further comprises a second transfer switch located in parallel to the first transfer switch between the input node and the output node to transfer the input charge to the output node.

Systems and methods for determining a touch input are provided. The systems and methods generally include measuring the peak voltage at an electrode over a measurement period and determining a touch input based on the peak voltage. The systems and methods can conserve computing resources by deferring digital signal processing until after a peak electrode capacitance has been sampled. The systems and methods are suitable for capacitive sensors using self-capacitance and capacitive sensors using mutual capacitance. The systems and methods are also suitable for capacitive buttons, track pads, and touch screens, among other implementations.

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.

Disclosed herein is an electrostatic capacitance detection circuit including a sense pin to which a sense electrode is to be connected, a ground pin to be grounded, a reference pin to be connected to a node where parasitic capacitance is to be formed between the node and the sense electrode, and a capacitance detection circuit connected to the sense pin, the ground pin, and the reference pin and configured to detect electrostatic capacitance formed by the sense electrode.

An operation input device includes a resistance element to generate a capacitance between an operating medium and the resistance element in response to an approach of the operating medium to the resistance element, and a power source to supply electric charge to one end and the other end of the resistance element. A first electric unit measures a first electric charge transfer amount supplied to the one end of the resistance element in response to generation of the capacitance. A second unit measures a second electric charge transfer amount supplied to the other end of the resistance element in response to generation of the capacitance. A controller is connected to the first and second units, and detects a position of the operating medium in a direction perpendicular to a surface of the resistance element based on a sum of the first and second electric charge transfer amounts.

Systems and methods for determining a touch input are provided. The systems and methods generally include measuring the peak voltage at an electrode over a measurement period and determining a touch input based on the peak voltage. The systems and methods can conserve computing resources by deferring digital signal processing until after a peak electrode capacitance has been sampled. The systems and methods are suitable for capacitive sensors using self-capacitance and capacitive sensors using mutual capacitance. The systems and methods are also suitable for capacitive buttons, track pads, and touch screens, among other implementations.

An apparatus includes a first electrode, a second electrode, and a third electrode having first and second opposing surfaces. The first opposing surface is adjacent the first electrode and separated from the first electrode by a first distance, and the second opposing surface is adjacent the second electrode and separated from the second electrode by a second distance. The third electrode is configured to move relative to the first and second electrodes. A capacitance sensing circuit is coupled to the first and second electrodes. The capacitive sensing circuit is configured to determine a capacitance using the first and second electrodes.

A capacitance detection circuit is provided, which includes a capacitance control module, a charge conversion module and a filter module connected with each other. The capacitance control module controls a capacitor to be charged/discharged for multiple times and generates a digital voltage signal according to an amount of received charges. The capacitor releases all stored charges after being charged to a preset voltage during each charge/discharge. In response to the digital voltage signal being at a high level, the charge conversion module outputs negative charges with a preset charge amount to the capacitance control module. The preset charge amount is greater than or equal to an amount of the stored charges when the capacitor is charged to the preset voltage. The filter module obtains a value representing a capacitance of the capacitor according to the digital voltage signal.

An embodiment of the present disclosure relates to a method of detection of a touch contact by a sensor including a first step of comparison of a voltage with a first voltage threshold; and a second step of comparison of the voltage with a second voltage threshold, the second step being implemented if the first voltage threshold has been reached within a duration shorter than a first duration threshold, the second voltage threshold being higher than the first voltage threshold.