It is disclosed a touch sensor (100,200,300,400,500,700) for sensing a user touch, comprising an electrically conductive structure (101) having an electrically conductive touch area (103) exposed to the environment; a first capacitor (115) having a first electrode (117) electrically connected with the conductive structure (101); a second capacitor (119) having a first electrode (121) connected to a second electrode (123) of the first capacitor (115); and a driver arrangement (125) connected to the first capacitor and the second capacitor and adapted to perform particular operation steps.

A keypad system uses capacitive touch switches in combination with one or more mechanical switches for ultra-low-power operation and/or increased functionality. A Capacitive switches are activated by touching different regions of a housing. A microcontroller detects the activation of the touch switches and communicate a code to a remote device in response to switch activation. The microcontroller preferably has a fully operational active state and a reduced functionality sleep state. Activation of at least one mechanical switch causes the microcontroller to awaken from the reduced functionality sleep state to the fully operational active state, thereby enabling the microcontroller to determine if one or more of the capacitive switches has been activated to communicate a corresponding code to the remote device. While ideally suited to vehicle-mounted keyless entry systems, the apparatus and methods find wider applicability in diverse fields of use.

A sensor circuit and method. The circuit includes a first subcircuit that includes a first sense capacitor, a first integration capacitor, and a first clock input for receiving a first digital clock signal for initiating discharge of the first integration capacitor at time T. The circuit includes a second subcircuit that includes a second sense capacitor, a second integration capacitor, and a second clock input for receiving a second digital clock signal for initiating discharge of the second integration capacitor at time T+T.sub.d. A rate of discharge of the first and second integration capacitors is at least partly determined by a capacitance of the first and second sense capacitor, respectively. At time T.sub.eval, after initiation of discharge of the first and second sense capacitors, the extent to which the first and second integration capacitors have discharged is compared. A digital signal indicating the result of the comparison is outputted.

According to a first aspect of the present disclosure, an electronic device for use in a touch-based user interface is provided, the electronic device comprising a first capacitor, a second capacitor, a third capacitor, and an analog-to-digital converter, wherein: the first capacitor and the second capacitor are switchably coupled to each other; the first capacitor is switchably coupled to an input of the analog-to-digital converter; the second capacitor is coupled to the input of the analog-to-digital converter; the third capacitor is coupled to the first capacitor; the third capacitor is switchably coupled to the second capacitor; the third capacitor is switchably coupled to the input of the analog-to-digital converter. According to a second aspect of the present disclosure, a corresponding method of manufacturing an electronic device for use in a touch-based user interface is conceived.

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.

The present application provides a capacitance sensing circuit, comprising an integrating circuit, comprising an integrating input terminal, coupled to the touch capacitance, wherein the integrating input terminal receives an input voltage; and an integrating output terminal, configured to output an output voltage; a comparator; a positive digital-to-analog (DA) converting unit; a negative DA converting unit; a control circuit, configured to control the positive DA converting unit and the negative DA converting unit; and a logic circuit, configured to output an output code, wherein the output code is related to a capacitance of the touch capacitance.

A sensor device for a motor vehicle includes a multi-layer circuit board on which a plurality of metallized planes are formed. A capacitive sensor electrode is formed on one of the planes for detection by capacitive approachment sensing. A control device controls the sensor electrode as a capacitive sensor electrode in order to detect approaches of a user towards the sensor electrode via an evaluation device. At least one planar electrode region is formed on each of the metallized planes, wherein each of the electrode regions is coupled to the control device. At least two of the electrode regions on different metallized planes are activated and evaluated as sensor electrodes and at least two of the electrode regions on different planes are activated and evaluated as the ground in a temporally offset manner.

An analog front end (AFE) can be implemented with automatic variable gain control for self-capacitance based touch- and proximity-sensitive touch sensor panels or touch screens. The AFE can include a charge amplifier and an oversampled analog-to-digital converter (ADC). The AFE can also include multiple signal paths between the charge amplifier and the ADC. The variable gain control can monitor the output of the oversampled ADC and, based on the oversampled ADC output, automatically select one of the multiple signal paths. When the output of the ADC indicates a proximity condition (e.g., relatively small signal, relatively large noise headroom when compared with a touch condition), the automatically selected signal path can amplify the charge amplifier output. The bit resolution of the oversampled ADC in the AFE can be relaxed as a result of the variable gain control.

The present disclosure describes aspects of a capacitance-to-voltage modulation circuit. In some aspects, the circuit is used in touch sensing. In some aspects, a modulation circuit comprises a first pair of switches having one switch connected between a voltage source and a capacitor, and another switch connected between ground and the input of the circuit. The circuit also includes a second pair of switches having one switch connected between the voltage source and the input of the circuit, and another switch connected between ground and the capacitor. A third pair of the circuit's switches comprise one switch connected between the capacitor and an input of an analog-to-digital converter (ADC) and another switch connected between the input of the circuit and the input of the ADC. The third pair of switches may enable charge sharing of signals modulated by the first and second pairs of switches, a result of which can used to sense touch input based on capacitance at the input of the circuit.

A sensor for providing an output signal that is a function of a sensed capacitance, in a touch interface for example. The sensor includes a charger for repetitively applying first and second voltages to charge the sensed capacitance to first and second charge values in first and second phases respectively. A sampler provides first and second sample signals that are a function of the first and second charge values respectively. An accumulator uses an accumulator signal to provide the output signal. The accumulator repetitively uses the first sample signal incrementally and the second sample signal decrementally in providing the accumulator signal. The accumulator signal is a progressive function of the sensed capacitance but tends to cancel a noise in the first and second sample signals at frequencies less than a repetition rate of operation of the accumulator.