Abstract: A capacitance sensing device includes a transmit (TX) generator for generating a sequence of receive (RX) signals by applying each TX signal pattern in a sequence of TX signal patterns to a set of sensor electrodes. For each TX signal pattern in the sequence of TX signal patterns, and for each subset of three or more contiguous sensor electrodes of the set of sensor electrodes, the TX generator applies to the subset one of a first excitation signal and a second excitation signal. The plurality of subsets includes at least half of the sensor electrodes in the set of sensor electrodes. The capacitance sensing device also includes a sequencer circuit coupled with the TX generator. For each TX signal pattern in the sequence of TX signal patterns, the sequencer circuit determines a next subsequent TX signal pattern in the sequence based on a circular rotation of the TX signal pattern. The capacitance sensing device also includes a processing block coupled with the TX generator.

Abstract: A system and method for synchronizing a stylus to a capacitive sense array. The system including a capacitive sense array which includes a plurality of electrodes. A magnetic field is generated using the plurality of electrodes. The magnetic field is used to synchronize the operation of the stylus and the capacitive sense array.

Abstract: A method includes providing a differential signal and generating an in-phase component of the differential signal and a quadrature component of the differential signal. The method further includes generating an output signal representing a capacitance value using the in-phase component and the quadrature component.

Abstract: An elongated stylus is configured to be capacitively coupled with a sensor array providing a plurality of electrodes to indicate a position on the sensor array. The stylus includes a housing having an end in an elongated direction of the housing, a conductive tip disposed at least partially extended from the end of the housing, an electrode disposed around the conductive tip and configured to at least partially expose the conductive tip, and a signal transmit drive circuit configured to provide a signal. Control is performed to form an electrical connection between the electrode and a ground and an electrical connection between the electrode and the signal transmit drive circuit when the elongated stylus is activated for capacitive coupling with the sensor array.

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.

Abstract: A system and method for synchronizing a stylus to a capacitive sense array. The system including a capacitive sense array which includes a plurality of electrodes. A magnetic field is generated using the plurality of electrodes. The magnetic field is used to synchronize the operation of the stylus and the capacitive sense array.

Abstract: A touch sensing apparatus includes a touch sensing surface having a plurality of TX electrodes and a plurality of RX electrodes. The touch sensing apparatus also includes capacitance sensing circuitry. The circuitry receives a plurality of drive signals. For each of a plurality of scanning stages, the circuitry applies a respective one of the plurality of drive signals to each of the plurality of TX electrodes substantially simultaneously according to a respective TX pattern. The respective TX pattern for each scanning stage is distinct. The circuitry receives sense signals from the plurality of RX electrodes. Each of the plurality of sense signals represents capacitance of a respective intersection of a respective TX electrode and a respective RX electrode. The circuitry then correlates the received sense signals for the plurality of scanning stages with the received drive signals to detect an object proximate to the touch panel.

Abstract: A circuit, system, and method for measuring or detecting pressure or force of a fingerprint on an array of electrodes is described. Pressure or force may be measured or detected using a processed image of the fingerprint, or by measurement of capacitance of deformed variable capacitors.

Abstract: A system and method for synchronizing a stylus to a capacitive sense array. The system including a capacitive sense array which includes a plurality of electrodes. A synchronization signal is transmitted to the stylus using the plurality of electrodes. The synchronization signal is transmitted to the stylus by capacitively coupling the stylus to the capacitive sense array.

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.

Abstract: A fingerprint sensing circuit, system, and method is disclosed. The fingerprint sensor maybe include a plurality of inputs coupled to a plurality of fingerprint sensing electrodes and to an analog front end. The analog front end may be configured to generate at least one digital value in response to a capacitance of at least one of the plurality of fingerprint sensing electrodes. Additionally, the analog front end may include a quadrature demodulation circuit to generate at least one demodulated value for processing by a channel engine. The channel engine may generate a capacitance result value that is based, in part, on the demodulated value and is stored in a memory.

Abstract: A capacitance sensing circuit may include a charge to digital converter, coupled to a signal receiver channel, to receive a signal from a capacitive sense array. The capacitance sensing circuit may also include a baseline compensation signal generator, coupled to the signal receiver channel, to provide a baseline compensation signal in an opposite phase of the signal to the signal receiver channel.

Abstract: A system and method for synchronizing a stylus to a capacitive sense array. The system including a capacitive sense array which includes a plurality of electrodes. A synchronization signal is transmitted to the stylus using the plurality of electrodes. The synchronization signal is transmitted to the stylus by capacitively coupling the stylus to the capacitive sense array.

Abstract: A system and method for synchronizing a stylus to a capacitive sense array. The system including a capacitive sense array which includes a plurality of electrodes. A synchronization signal is transmitted to the stylus using the plurality of electrodes. The synchronization signal is transmitted to the stylus by capacitively coupling the stylus to the capacitive sense array.

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.

Abstract: An elongated stylus is configured to be capacitively coupled with a sensor array providing a plurality of electrodes to indicate a position on the sensor array. The stylus includes a housing having an end in an elongated direction of the housing, a conductive tip disposed at least partially extended from the end of the housing, an electrode disposed around the conductive tip and configured to at least partially expose the conductive tip, and a signal transmit drive circuit configured to provide a signal. Control is performed to form an electrical connection between the electrode and a ground and an electrical connection between the electrode and the signal transmit drive circuit when the elongated stylus is activated for capacitive coupling with the sensor array.

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.

Abstract: An elongated stylus is configured to be capacitively coupled with a sensor array providing a plurality of electrodes to indicate a position on the sensor array. The stylus includes a housing having an end in an elongated direction of the housing, a conductive tip disposed at least partially extended from the end of the housing, an electrode disposed around the conductive tip and configured to at least partially expose the conductive tip, and a signal transmit drive circuit configured to provide a signal. Control is performed to form an electrical connection between the electrode and a ground and an electrical connection between the electrode and the signal transmit drive circuit when the elongated stylus is activated for capacitive coupling with the sensor array.

Abstract: An elongated stylus is configured to be capacitively coupled with a sensor array providing a plurality of electrodes to indicate a position on the sensor array. The stylus includes a housing having an end in an elongated direction of the housing, a conductive tip disposed at least partially extended from the end of the housing, an electrode disposed around the conductive tip and configured to at least partially expose the conductive tip, and a signal transmit drive circuit configured to provide a signal. Control is performed to form an electrical connection between the electrode and a ground and an electrical connection between the electrode and the signal transmit drive circuit when the elongated stylus is activated for capacitive coupling with the sensor array.

Abstract: A method for detecting fingerprint spoof objects includes detecting a presence of the object at a fingerprint sensor and, in response to detecting the presence of the object, measuring a set of physical properties of the object based on one or more signals from a set of electrodes of the fingerprint sensor. The set of physical properties includes at least one of a subdermal compliance of the object and a surface adhesiveness of the object. The method further includes distinguishing the object as an actual finger or a spoof based on the one or more physical properties.