Abstract: A method, apparatus, and system are described to perform, by a capacitance-sensing circuit, capacitance sensing of an electrode of a capacitive sense array of electrodes. Performing the capacitance sensing includes integrating, on a passive integrator circuit, charge from a sensed capacitance of the electrode of the capacitive sense array. The passive integrator circuit integrates the charge on a self-capacitance of the electrode as part of the integrating. The capacitance-sensing circuit converts the charge from the sensed capacitance of the electrode into a digital value representing the sensed capacitance of the electrode.

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: Apparatus and methods of de-convolution for multi-phase scans of an array of electrodes are described. One programmable circuit includes a sequencer to initiate a multi-phase transmit (TX) scan of an array of electrodes to obtain capacitance data. The capacitance data is stored in one or more storage devices as convoluted capacitance data. The programmable circuit also includes a digital circuit block to read the convoluted capacitance data from the one or more storage devices, de-convolve the convoluted capacitance data to obtain de-convoluted capacitance data, and store the de-convoluted capacitance data in the one or more storage devices.

Abstract: Systems and methods of visualizing capacitance sensing system operation. A graphical user interface for visualizing capacitance sensing system operation includes a first window. The window includes a representation of a physical layout of a plurality of sensor devices on a target apparatus. The graphical user interface is operable to accept input from a pointing device to select a selected sensor from the plurality of sensor devices. A second window is for displaying capacitive sensing data of the selected sensor.

Abstract: Techniques for fully-differential multi-phase scanning in capacitive fingerprint applications are described herein. In an example embodiment, a system comprises a capacitive fingerprint sensor array and a processing device coupled to the capacitive fingerprint sensor array. The processing device is configured at least to: scan the capacitive fingerprint sensor array in a fully-differential multi-phase mode; receive a plurality of measurements that represents a portion of finger on the capacitive fingerprint sensor array; and generate a fingerprint image for the portion of the finger based on the plurality of measurements. In some embodiments, a capacitive fingerprint sensor array may include receive (RX) electrodes and one or more reference electrodes configured to detect noise, where the one or more reference electrodes have width that is substantially equal to the width of the RX electrodes, but the one or more reference electrodes are disposed at a smaller pitch than the RX electrodes.

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: Apparatuses and methods of high-voltage capacitance-sensing circuits are described. One apparatus includes a capacitance-sensing circuit coupled to a capacitive-sense array of electrodes. The capacitance-sensing circuit includes a self-capacitance sensing channel, a first voltage source (e.g., a low-voltage drive source) to drive a reference voltage, and a second voltage source (e.g., high-voltage drive source) to drive a sensing voltage. The sensing voltage is greater in magnitude than the reference voltage. The capacitance-sensing circuit also includes 1) a first set of switches to selectively couple the self-capacitance sensing channel or the second voltage source to a sensing electrode of the capacitance-sensing array; and 2) a second set of switches to selectively couple the first voltage source or the second voltage source to a shielding electrode of the capacitance-sensing array.

Abstract: A method can include determining multiple sensed positions of an object path in a touch sense region; generating at least a first predicted position from the sensed positions; and filtering a sense position, including associating the sense position with the object path if it is within a first proximity to at least the first predicted position, and not associating the sense position with the object path if it is outside of at least the first proximity from the first predicted position.

Abstract: A system comprises a processing device and a capacitive sense array that includes a plurality of electrodes. The system performs a first scan of a plurality of electrodes in a capacitive sense array to determine a position of a stylus. The system also performs one or more additional scans of subsets of the plurality of electrodes to determine additional positions of the stylus. The system may continually perform the additional scans on of the subsets of the plurality of electrodes until the stylus is no longer detected.

Abstract: Apparatuses and methods of multi-phase scanning are described.

Abstract: Apparatus and methods of de-convolution for multi-phase scans of an array of electrodes are described. One programmable circuit includes a sequencer to initiate a multi-phase transmit (TX) scan of an array of electrodes to obtain capacitance data. The capacitance data is stored in one or more storage devices as convoluted capacitance data. The programmable circuit also includes a digital circuit block to read the convoluted capacitance data from the one or more storage devices, de-convolve the convoluted capacitance data to obtain de-convoluted capacitance data, and store the de-convoluted capacitance data in the or more storage devices.

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: Apparatuses and methods to reduce the influence of a noise signal on touch screen controllers are described. One apparatus includes a detector to determine a presence of a noise signal from a display coupled to a capacitive touch screen. The apparatus also includes a synchronization circuit to synchronize signals produced by a touch screen controller with the noise signal to reduce the influence of the noise signal on capacitance measurements by the touch screen controller.

Abstract: A method can include determining multiple sensed positions of an object path in a touch sense region; generating at least a first predicted position from the sensed positions; and filtering a sense position, including associating the sense position with the object path if it is within a first proximity to at least the first predicted position, and not associating the sense position with the object path if it is outside of at least the first proximity from the first predicted position.

Abstract: An apparatus comprising a stylus with a dynamically switch tip shield is provided. The apparatus includes an elongated stylus housing having an end, a conductive tip disposed at least partially inside the stylus housing and extending from the end, a force sensor coupled to the conductive tip and configured to detect contact between the conductive tip and an object, a tip shield coupled with the stylus housing and extending from the end, and a switch coupled to the tip shield and the conductive tip. The force sensor may be an inductive sensor, a capacitive sensor, a piezo sensor, a force sensing resistor sensor, or an optical sensor.

Abstract: An apparatus and method of converting a capacitance measured on a sensor element to a digital value. The apparatus may include a matrix-scanning device including drive lines and sense lines. A sense element is located at an intersection of one of the drive lines and one of the sense lines. The apparatus also includes a modulation circuit coupled to the drive lines and the sense lines, and a switching circuit having first switches controlled by a clock. The modulation circuit is configured to measure a mutual capacitance on the sense element and to convert the measured mutual capacitance to a first digital value. The modulation circuit is configured to measure a self-capacitance on at least one of the drive lines and to convert the measured self-capacitance to a second digital value.

Abstract: An apparatus and method of converting a capacitance measured on a sensor element to a digital value. The apparatus may include a switching capacitor as a sensor element, a modulation circuit coupled to the sensor element, and a switching circuit having a plurality of switches controlled by a variable-period clock. The modulation circuit is configured to measure a capacitance on the sense element and to convert the measured capacitance to a digital value.

Abstract: Apparatuses and methods of high-voltage capacitance-sensing circuits are described. One apparatus includes a capacitance-sensing circuit coupled to a capacitive-sense array of electrodes. The capacitance-sensing circuit includes a self-capacitance sensing channel, a first voltage source (e.g., a low-voltage drive source) to drive a reference voltage, and a second voltage source (e.g., high-voltage drive source) to drive a sensing voltage. The sensing voltage is greater in magnitude than the reference voltage. The capacitance-sensing circuit also includes 1) a first set of switches to selectively couple the self-capacitance sensing channel or the second voltage source to a sensing electrode of the capacitance-sensing array; and 2) a second set of switches to selectively couple the first voltage source or the second voltage source to a shielding electrode of the capacitance-sensing array.

Abstract: A method for improving noise immunity of capacitive sensing circuit associated with a touch sense array is disclosed. The capacitive sensing circuit receives a response signal from a touch sense array. The capacitive sensing circuit measures a noise component of the response signal. When a level of noise of the noise component within a passband of the capacitive sensing circuit is greater than a threshold, the capacitive sensing circuit changes at least one parameter of capacitive sensing circuit to move the passband substantially outside the frequency spectrum of the noise component.

Abstract: Apparatuses and methods to reduce the influence of a noise signal on touch screen controllers are described. One apparatus includes a detector to determine a presence of a noise signal from a display coupled to a capacitive touch screen. The apparatus also includes a synchronization circuit to synchronize signals produced by a touch screen controller with the noise signal to reduce the influence of the noise signal on capacitance measurements by the touch screen controller.