Abstract: A capacitive sensor includes a first electrode structure; a second electrode structure that is counter to the first electrode structure, wherein the second electrode structure is movable relative to the first electrode structure and is capacitively coupled to the first electrode structure to form a capacitor having a capacitance that changes with a change in a distance between the first electrode structure and second electrode structure; a signal generator configured to apply an electrical signal at an input or at an output of the capacitor to induce a voltage transient response at the output of capacitor; and a diagnostic circuit configured to detect a fault in the capacitive sensor by measuring a time constant of the first voltage transient response and detecting the fault based on the time constant and based on whether the first electrical signal is the pull-in signal or the non-pull-in signal.

Abstract: A method for testing crosstalk effect includes: obtaining a test signal and an interference input signal; inputting the test signal into a crosstalk effect test circuit obtained by simulation, so as to obtain an interfered signal; and when a rise time of the interfered signal or a fall time of the interfered signal is greater than a preset time threshold, determining that an excessive crosstalk effect exists in an integrated circuit under test. The crosstalk effect test circuit includes a first circuit, N second circuits, and N capacitors. The first circuit is configured to simulate an interfered first signal circuit in the integrated circuit under test; the N second circuits are configured to simulate N second signal circuits that interfere with the first signal circuit in the integrated circuit under test.

Abstract: Systems and methods for measuring air gaps between opposing surfaces of two structural components. In one application, such measurements are used to fabricate a shim that fills the air gap between two structural members, such as parts of an aircraft. The resonant inductive coupling-based sensing system has the capability to remotely measure an air gap using an on-board transmit system. Furthermore, the system has the capability to switch between multiple inductor-capacitor sets such as to simultaneously measure air gaps across an area so that a better profile of the air gap can be determined. The resonant inductive coupling-based gap sensor is configured as signal generating and signal sensing electronics printed or mounted on respective flexible substrates to provide a flexible and portable measurement solution.

Abstract: A method and apparatus are provided for fingerprint identification in the field of terminal technology. The method may include: when a touch operation for fingerprint identification is detected on a display screen, determining an acting area and a touch position of the touch operation on the display screen; and determining a fingerprint image corresponding to the touch operation and performing the fingerprint identification, when the acting area is greater than or equal to a first preset area threshold and the touch position is located in a preset identification region on the display screen.

Abstract: According to one embodiment, a sensor includes a base body, and a first sensor part. The first sensor part includes fixed and movable electrode members, and first and second support members. The fixed electrode member includes a fixed electrode fixed to the base body. The movable electrode member includes a movable electrode. The movable electrode member includes first and second movable portions, and a third movable portion between the first and second movable portions. The first support member is fixed to the base body and connected with the first movable portion. The second support member is fixed to the base body and connected with the second movable portion. The first and second support members support the movable electrode member to provide a first gap between the fixed and movable electrode members. The fixed electrode member includes first, second, and third fixed electrode portions facing the movable portion.

Abstract: A process for merging webs for the production of an electrode assembly for a secondary battery, the process comprising: moving a first web comprising a population of first components for electrode sub-units, the first components delineated by corresponding weakened patterns, and a population of first conveying features. Moving a second web comprising a population of second components for the electrode sub-units, the second components delineated by corresponding weakened patterns, and a population of second conveying features. Conveying a receiving member, the receiving member comprising a plurality of projections. Receiving the first web on the receiving member. Overlaying, the second web on the first web such that the first components are aligned with the second components and the conveying features of the second web are engaged by the plurality of projections on the receiving member. The second web merge location being spaced from the first web merge location.

Abstract: A sensor arrangement comprises an integrator with an integrator input, a sensor coupled to the integrator input, a balancing current generator coupled to the integrator input and a compensation current generator coupled to the integrator input.

Abstract: The embodiments of the present application provide a detection method and a detection device. The detection device includes: a capacitance generation circuit comprising a first capacitance electrode and a second capacitance electrode disposed opposite to each other, and a power source coupled to the first and the second capacitance electrode, the first capacitance electrode is an electrode plate, and the second capacitance electrode comprises n sub-electrodes which are provided to be insulated from each other; at least one capacitance detection circuit coupled to the electrode plate and the sub-electrodes, and configured to detect a capacitance value between the electrode plate and the sub-electrodes in response to a substrate to be tested being placed on one side of the electrode plate; and a controller configured to determine, according to the detected capacitance value, whether a foreign object exists in a region on the substrate to be tested or not.

Abstract: A process is described that includes flowing a carrier fluid through a transfer line, feeding polymer pellets into the transfer line at a feed location, measuring a first pressure value of the carrier fluid at a location in the transfer line upstream of the feed location, measuring a second pressure value of the carrier fluid and polymer pellets at a downstream location in the transfer line which is downstream of the feed location, and determining a mass flow rate of the polymer pellets flowing in the transfer line based on a differential pressure between the first pressure value and the second pressure value.

Abstract: A system and method for incorporating occupancy-detecting technology into furniture is provided. More particularly, the invention relates to detecting occupancy in a recliner using a sinuous wire detection array incorporated into a seat. Further embodiments of the invention are directed to a system and method for incorporating capacitance detection technology with one or more conductive features of a recliner mechanism. In some aspects, a sensor is provided based on coupling one or more conductive features to a control component of the capacitance detector control component. A controller may determine the corresponding response based on occupancy detection and/or presence detection. A processor may receive information regarding changes in capacitance and determines when a change in voltage satisfies a threshold. Based on a determination of occupancy and/or presence, a variety of corresponding features of the adjustable recliner may be activated.

Abstract: Disclosed herein is a touch screen controller operable with a touch screen having force lines and sense lines. The touch screen controller includes drive circuitry driving the force lines with a force signal in a touch data sensing mode and not driving the force lines in a noise sensing mode. Sense circuitry senses data at the sense lines in the touch data sensing mode and the noise sensing mode. Processing circuitry samples the data, multiplies the data by a sine multiplier to produce imaginary data, sums the imaginary data, multiplies the data by a cosine multiplier to produce real data, sums the real data, and determines magnitude values of the data as a function of the imaginary data and the real data.

Abstract: A touch control display panel, a touch control display device and a touch control display panel driving method are provided. The touch control display panel comprises a first substrate; a second substrate arranged opposite to the first substrate; a plurality of first electrodes disposed on the first substrate, a plurality of second electrodes disposed in a gap between two first electrodes and electrically insulated from the first electrodes, wherein the plurality of first electrodes and the plurality of second electrodes are disposed in a same layer; a third electrode disposed on the second substrate, wherein an orthogonal projection of the third electrode on the first substrate is at least overlapped with an orthogonal projection of the second electrodes on the first substrate; and at least one controlling unit connected to the first electrodes, the second electrodes and the third electrode.

Abstract: Method for calculating model parameters for a capacitor to be modelled, the method comprising the following steps of: incorporating the capacitor to be modelled into a DC to DC converter with at least a first switching element; connecting a resistive load between the output terminals; applying an input voltage to the input terminals of the converter; controlling the first switching element in accordance with a frequency and duty cycle in order to obtain a current varying periodically in time through the capacitor to be modelled; measuring at least a first quantity representative of the current through the capacitor and at least a second quantity representative of the voltage across the capacitor; determining on the basis of the measured first and second quantities at least one current value for the current through the capacitor and at least one voltage value for the voltage across the capacitor.

Abstract: A contactless, electromagnetic (EM) replacement (substitute, alternative) for cabled (electric) Standards-based interfaces (such as, but not limited to USB) which effectively handles the data transfer requirements (such as bandwidth, speed, latency) associated with the Standard, and which is also capable of measuring and replicating relevant physical conditions (such as voltage levels) on data lines so as to function compatibly and transparently with the Standard. A contactless link may be provided between devices having transceivers. A non-conducting housing may enclose the devices. Some applications for the contactless (EM) interface are disclosed. A dielectric coupler facilitating communication between communications chips which are several meters apart. Conductive paths may provide power and ground for bus-powered devices.

Abstract: In a case where the amplitude of a detection voltage is increased, the amplitude of a drive current flowing in a detection-target capacitor also increases, and thus, the amplitude of a detection current also increases. In this case, the increase in amplitude of the detection current is not directly restricted by the condition of a power supply voltage range enabling a circuit to operate. For this reason, a current conversion ratio of a current output circuit or a capacitance value of a capacitor of a current-voltage conversion circuit is set to an appropriate value so as not to cause a voltage to exceed the power supply voltage range, thereby preventing the amplitude of the detection current from being restricted by the condition of the power supply voltage range. Therefore, it is possible to increase the amplitude of the detection voltage to a maximum within the power supply voltage range.

Abstract: An apparatus includes a driver circuit and a sensing system. The driver circuit includes an operational transconductance amplifier and a current mirror. The current mirror is coupled to the operational transconductance amplifier. The sensing system is coupled to the first current mirror. The sensing system is operable to detect a touch based on a change in capacitance at an electrode of a plurality of electrodes of a touch sensor.

Abstract: A contactless, electromagnetic (EM) replacement (substitute, alternative) for cabled (electric) Standards-based interfaces (such as, but not limited to USB) which effectively handles the data transfer requirements (such as bandwidth, speed, latency) associated with the Standard, and which is also capable of measuring and replicating relevant physical conditions (such as voltage levels) on data lines so as to function compatibly and transparently with the Standard. A contactless link may be provided between devices having transceivers. A non-conducting housing may enclose the devices. Some applications for the contactless (EM) interface are disclosed. A dielectric coupler facilitating communication between communications chips which are several meters apart. Conductive paths may provide power and ground for bus-powered devices.

Abstract: Devices and methods related to liquid crystal displays (LCDs) are provided. For example, such an electronic device may include an LCD with a slew rate control unit that adjusts a slew rate for source drivers of the LCD. The slew rate may be adjusted differently for each source driver and for each frame of data signal delivered by the source driver. Individually adjusting the slew rate of the source driver enables the LCD to respond to or reduce noise within the LCD that may otherwise contribute to flickering or other unwanted display events.

Abstract: Sampling for arc-fault detection, ground-fault detection, and grounded-neutral fault detection uses a single analog-to-digital converter (ADC). The arc-fault and ground-fault sampling occurs at regular sampling periods that are relatively short com pared to the time between them, thus allowing grounded-neutral fault sampling to occur before and/or after one of these sampling periods. A predefined event may be used to ensure the grounded-neutral fault sampling occurs immediately before and/or after one of the periodic sampling periods. The predefined event may be the expiration of a timer or the time for a sinusoidal signal in a ground fault sense circuit to make a predefined number of zero-crossings. This avoids interference between the arc-fault sampling, the ground-fault sampling and grounded-neutral fault sampling, allowing a single ADC to perform all samplings concurrently. The timing of the predefined event may be periodically reset to compensate for any changes due to temperature and/or over time.

Abstract: A sensor assembly is described herein that can automatically calibrate itself upon installation into an empty bin, eliminating the need to actually fill the bin to calibrate the level reading. The sensor will provide consistent measurement regardless of material properties (permittivity, density, temperature or moisture content). The capacitive nature of the sensor means that in some circumstances, it will sense the material through plastic/glass/fiber glass thereby allowing the sensor assembly to be mountable on the outside of a bin or container. The electrodes of the sensor system are designed to provide a continuous level reading.

Abstract: A sensor unit outputs detection data as the detection result of the approach state of an object at a plurality of detection positions. A noise amount calculation unit calculates noise included in the detection data as the amount of noise. Then, when a filter unit attenuates the noise included in the detection data, the noise attenuation characteristics of a low-pass filtering process are changed depending on the calculated amount of noise such that the attenuation of noise increases as the amount of noise increases and decreases as the amount of noise decreases.

Abstract: A signal processing circuit is connected to one of a plurality of conductors of a position detection sensor having a self-capacitance and configured to generate a signal indicative of the self-capacitance for use in correcting a pointer position detection signal. The circuit includes a capacitor circuit and detects a change in capacitance between the conductor and a pointer (e.g., a finger) as a change in voltage in the capacitor circuit. The signal processing circuit further includes: a gate circuit which controls the connection between the capacitor circuit and the conductor; and a voltage supply control circuit which temporarily sets, to a defined voltage level, a first end of the gate circuit to which the conductor is connected and sets a defined potential difference between the first end and another (second) end of the gate circuit to which the capacitor circuit is connected.

Abstract: A contactless, electromagnetic (EM) replacement (substitute, alternative) for cabled (electric) Standards-based interfaces (such as, but not limited to USB) which effectively handles the data transfer requirements (such as bandwidth, speed, latency) associated with the Standard, and which is also capable of measuring and replicating relevant physical conditions (such as voltage levels) on data lines so as to function compatibly and transparently with the Standard. A contactless link may be provided between devices having transceivers. A non-conducting housing may enclose the devices. Some applications for the contactless (EM) interface are disclosed. A dielectric coupler facilitating communication between communications chips which are several meters apart. Conductive paths may provide power and ground for bus-powered devices.

Abstract: A bandpass sense amplifier circuit (FIG. 2A) is disclosed. The circuit includes a capacitor (C0) having a first terminal coupled to receive an input signal (Vin) and a second terminal. A current conveyor circuit (200-206,212) has a third terminal (X) coupled to the second terminal of the capacitor and a fourth terminal (Z) arranged to mirror a current into the third terminal. A voltage follower circuit (214) has an input terminal coupled to the fourth terminal of the current conveyor circuit and an output terminal.

Abstract: An input system includes a touch panel, a control circuit, a stylus pen, and a connection link. The control circuit generates an electrical signal. The stylus pen is external to the control circuit. The connection link is coupled between the control circuit and the stylus pen, and transmits the electrical signal to the stylus pen, wherein the electrical signal is coupled to the touch panel via the stylus pen. The connection link may be a wired link or a wireless link.

Abstract: An embodiment of the present invention provides an apparatus, comprising' an RF matching network connected to at least one RF input port and at least one RF output port and 5 including one or more voltage or current controlled variable reactive elements; a voltage detector connected to the at least one RF output port via a variable voltage divider to determine the voltage at the at least one RF output port and provide voltage information to a controller that controls a bias driving circuit which provides voltage or current bias to the RF matching network; a variable voltage divider connected to the voltage detector and implemented using a 10 multi-pole RF switch to select one of a plurality of different resistance ratios to improve the dynamic range of the apparatus; and wherein the RF matching network is adapted to maximize RF power transferred from the at least one RF input port to the at least one RF output port by varying the voltage or current to the voltage or current controlled variable reactive elemen

Abstract: A sensor arrangement comprises an input surface, an optical sensor, a first capacitive sensor, an evaluation unit and a device. The input surface has at least one light-permeable part surface. The optical sensor is disposed below the at least one light-permeable part surface. The first capacitive sensor is disposed below the input surface. The evaluation unit is coupled to the optical sensor and configured to carry out a light-permeability measurement of an object located on the input surface using the optical sensor. The device is configured to evaluate a change in capacitance of the first capacitive sensor. The device is connected to the first capacitive sensor and further configured to generate a first output signal if there is a change in capacitance. The evaluation unit is further configured to generate a presence signal if a measured light permeability falls below a predetermined value.

Abstract: A detection circuit for a capacitive sensor includes a drive signal generator for applying drive signal varying between first and second levels to a sensor common terminal, a sense amplifier having input terminals respectively connected to sensor detection terminals, and a controller for controlling input common-mode voltage of the sense amplifier to predetermined voltage. The controller includes a feedback amplifier for outputting feedback voltage according to difference between the common-mode and predetermined voltages, a pair of feedback capacitors having one ends respectively connected to the detection terminals and another ends connected together, and a voltage switcher for applying preset voltage, between the predetermined voltage and a limit voltage outputtable by the feedback amplifier in direction where the second level exists relative to the first level, to the other ends during the first level and the feedback voltage to the other ends during the second level.

Abstract: An occupant sensor device includes a sensor body unit disposed in a base part of a seat in a vehicle, and an occupant detection device. The sensor body unit is divided into at least two parts, such as a first sensor part and a second sensor part, where the first sensor part is positioned in front of the second sensor part. Based on a capacitance between the sensor body unit and a vehicle body, the occupant detection device detects an occupant type of an occupant that is seated on the seat. In particular, the occupant detection unit is able to detect the occupant type based on a first capacitance provided by the first sensor part, a second capacitance provided by the second sensor part, and a total capacitance, which is a total of the first capacitance and the second capacitance.

Abstract: A detection circuit for a capacitive sensor includes a drive signal generator for applying drive signal to a sensor common terminal, a sense amplifier having input terminals respectively connected to sensor detection terminals, and a controller for controlling input common-mode voltage of the sense amplifier to predetermined voltage. The controller includes a feedback amplifier for outputting feedback voltage according to difference between the common-mode and predetermined voltages, a pair of first feedback capacitors having one ends respectively connected to the detection terminals and another ends connected together, a second feedback capacitor having one end connected to the other ends, and a voltage switcher for applying first preset voltage to the other ends during first level of the drive signal and for applying second preset voltage to the other ends and the predetermined voltage to another end of the second feedback capacitor during second level of the drive signal.

Abstract: The capacitive measuring circuit for a moved elongated test material contains at least two measuring capacitors, each of which is configured for receiving the test material. It further contains electrically actuatable selection means, by means of which one of the measuring capacitors can be selected in such a way that only the selected measuring capacitor contributes to the measurement, whereas the other measuring capacitors do not. As a result, the total capacitance of the measuring circuit is reduced and its sensitivity is increased.

Abstract: A sensor system has a first sensor device and a second capacitive sensor device for detecting a movement of the object relative to a detection surface, wherein the sensor system may be operated in a first mode of operation and in a second mode of operation, wherein the sensor system may be switched over from the first mode of operation into the second mode of operation, wherein the second capacitive sensor device has a number of second sensor electrodes, and wherein in the sensor system at least in the second mode of operation at least one signal path connectable with a predetermined fixed electric potential is provided, which is parallel to a parasitic capacitance of the first sensor device.

Abstract: Methods, systems and apparatus are provided for generating voltage commands used to control operation of a permanent magnet machine. For example, a control system is provided that generates voltage command signals for controlling a permanent magnet machine during a transition from an initial operating condition to a final operating condition. The control system includes a processor configured to execute software instructions, and a memory configured to store software instructions accessible by the processor. The software instructions comprise a voltage command generator module. Based on an electrical angular frequency of the permanent magnet machine, and synchronous reference frame current signals, the voltage command generator module is configured to generate ramped voltage command signals that each change linearly in accordance with a slope during a transition period that is set to a rise time.

Abstract: A capacitive occupant detection system comprises at least one antenna electrode to be arranged in a seat and an evaluation unit operatively coupled to said at least one antenna electrode, said evaluation unit being configured for applying, during operation, an alternating voltage signal to said antenna electrode and for detecting an amplitude and/or phase of a displacement current flowing from said antenna electrode towards ground. According to the invention said antenna electrode comprises an antenna electrode conductor and at least one dedicated ground electrode, said ground electrode being arranged at a predetermined distance of said antenna electrode conductor and extending along said antenna electrode conductor.

Abstract: A device for testing capacitive loads of a power supply includes a controller, a power supply switching circuit, a capacitive load switching circuit, and a current sampling circuit. The power supply switching circuit selects one of output voltages of the power supply to be electronically connected to the capacitive load switching circuit and the current sampling circuit. The current sampling circuit samples an output current of one output of the power supply selected by the controller. The controller turns on and off switches of the capacitive load switching circuit for matching an output current of the power supply with a reference current until the output current equals to the reference current. The controller outputs a total magnitude of the capacitive loads.

Abstract: An electronic circuit with a plurality of connections for a plurality of sensor elements is provided, wherein the electronic circuit is configured to detect, with at least one multiplexing method, the presence of an object in at least one observation area of the sensor elements and to distinguish between the sensor elements. Also a method for determining the position of at least one object situated in at least one observation area of sensor elements relative to the sensor elements is provided, whereby with a multiplexing method an electric variable for each sensor element is detected, which is indicative for the presence of the object in the respective observation area.

Abstract: A sensor arrangement comprises an input surface, an optical sensor, a first capacitive sensor, an evaluation unit and a device. The input surface has at least one light-permeable part surface. The optical sensor is disposed below the at least one light-permeable part surface. The first capacitive sensor is disposed below the input surface. The evaluation unit is coupled to the optical sensor and configured to carry out a light-permeability measurement of an object located on the input surface using the optical sensor. The device is configured to evaluate a change in capacitance of the first capacitive sensor. The device is connected to the first capacitive sensor and further configured to generate a first output signal if there is a change in capacitance. The evaluation unit is further configured to generate a presence signal if a measured light permeability falls below a predetermined value.

Abstract: A capacitor based sensor for angular position detection having two fixed plates arranged at an angle and a semicircular rotating plate in between. The sensor can determine any angular position in the full 0-360 degrees range. The sensor may be temperature compensated, and integrated with electronics such that sensor module only has two electrical leads, one for input power and one for input/output digital data. A method for converting capacitance measurements to an angle is also disclosed.

Abstract: A method for compensating for a dielectric absorption effect in a measurement configuration during measurements by an instrument having measurement terminals includes providing a feedback loop in the instrument, the loop having a gain adjustment and a simulation impedance and being adapted to provide a signal counter to the dielectric absorption at the measurement terminals; applying a transient calibration signal to the test terminals for at least two values of the gain adjustment; measuring a response to the calibration signal for each of the at least two values; and determining an operating value of the gain adjustment based on the measured responses. The operating value is used for subsequent measurements by the instrument, the simulation impedance modeling the dielectric absorption characteristics of the measurement configuration.

Abstract: A capacitive sensor may include a transmit electrode and a receive electrode capacitively coupled with the transmit electrode. A capacitance sensing circuit senses a capacitance between the transmit and receive electrodes by applying a signal to the transmit electrode and rectifying a signal induced at the receive electrode. A compensation circuit reduces the effect of a mutual and parasitic capacitances of the transmit and receive electrode pair by adding a compensation signal to the rectified signal.

Abstract: A compensating circuit which has a programmable capacitance array for measuring AC voltage is disclosed in the present invention. The compensating circuit includes a pair of first leads for linking to an AC circuit; a variable capacitor, electrically linked to the first leads, for providing different capacitance value according to a programmable capacitance array; and a control unit, electrically linked to the first leads, for changing the capacitance value of the variable capacitor as one capacitance of the programmable capacitance array according to an external instruction. Since the capacitance of the compensating circuit is changeable, and AC voltage meter designed with the compensating circuit is able to measure voltage in wider range of frequency.

Abstract: A system and method for testing capacitance of a load circuit connected to an output pin of a driving circuit In one embodiment, the method may comprise driving a voltage at the output pin to a first voltage; a predetermined current to the output pin; comparing the voltage at the output pin to a reference voltage; and when the voltage at the output pin matches the reference voltage, generating an estimate of capacitance present at the output pin based on a number of clock cycles occurring between an onset of a timed voltage change period and a time at which the voltage at the output pin matches the reference voltage.

Abstract: A method of determining a measure of a total capacitance of one or more capacitive elements connected to an output of a switched mode power supply is described. The method includes generating a voltage control signal to cause an output voltage controller to sweep a voltage at the output of the switched mode power supply from an initial voltage value to a final voltage value. Sample values of a current at the output measured by a current sampler during the sweep of the output voltage are received, and an integrated current value representing a measure of the total capacitance using the received sample values is calculated.

Abstract: A method for measuring for generating a touch capacitance measurement is provided. Gain and offset control signals are generated, where the gain and offset control signals are adjusted to compensate for base capacitance of a touch sensor. The gain control signal is applied to a touch sensor during a first phase of a clock signal, and the offset control signal is applied to an output circuit during a second phase of the clock signal. The output circuit is coupled to the touch sensor during the second phase of the clock signal. The touch capacitance measurement is generated by compensating for the base capacitance with the gain and offset control signals, and a gain is applied to the touch capacitance measurement.

Abstract: A process measurement system includes a sensor for producing a sensor signal as a function of a process parameter and a measurement circuit that converts the sensor signal to measurement data. A control circuit controls the amplitude of the sensor excitation to maximize signal strength over the entire operating ratio range of the sensor. This enhances resolution and noise rejection of the measurement circuit.

Abstract: An apparatus for generating a sensor signal indicating information on a capacitance of a variable capacitor including a variable capacitance includes a sensor unit and a compensation unit. The sensor unit is configured to generate a sensor signal indicating information on a varying current flowing through a connection between the sensor unit and the variable capacitor caused by a variation of the capacitance of the variable capacitor while the variable capacitor is biased by a predefined bias voltage. Further, the compensation unit is configured to influence the sensor signal or to provide a compensation signal capable of influencing the sensor signal so that the sensor signal includes less nonlinear signal portions than a sensor signal without the influence of the compensation unit or the compensation signal.

Abstract: An internal sampling capacitor of an analog-to-digital converter (ADC) in a digital device is charged to a reference voltage, then some of the voltage charge on the internal sampling capacitor is transferred to an external unknown capacitor through a low resistance switch internal to the digital device. After the charge transfer has stabilized, the voltage charge remaining on the internal sampling capacitor is measured. The difference between the known reference voltage and the voltage remaining on the internal sampling capacitor is used to determine the capacitance value of the external capacitor. Alternatively, the external capacitor may be charged to a reference voltage then the external capacitor is coupled to the internal sampling capacitor, e.g., having no charge or a known charge on it, and the resulting voltage charge on the internal sampling capacitor is measured and used for determining the capacitance value of the external capacitor.

Abstract: Apparatuses and methods of capacitive buttons and detecting and differentiating touches from different size conductive objects on the capacitive buttons. One apparatus includes a capacitance-sensing circuit coupled to a capacitive button. The capacitive button includes a first sense element and a second sense element. The capacitance-sensing circuit is operative to measure signals from the first sense element and the second sense element with a sensing parameter (also referred to as tuning properties) set to a first value. The signals correspond to capacitances of the first sense element and second sense element. An inner perimeter of the first sense element is disposed to surround (at least in part) an outer perimeter of the second sense element. The apparatus further includes processing logic coupled to the capacitance-sensing circuit.

Abstract: A wearable device includes a capacitive sensor and capacitance sensing and calibration logic operative to determine that component drift for a capacitive sensor cannot be determined based on a capacitance sensed by the capacitive sensor. The capacitance sensing and calibration logic deactivates a drift calibration operation for the capacitive sensor while the capacitive sensor senses the capacitance. The capacitance sensing and calibration logic is further operative to determine that the capacitance sensed by the capacitive sensor is within a detection threshold that indicates that a conductive surface is within proximity of the capacitive sensor. The capacitance sensing and calibration logic can also determine that a wearable device, that includes the capacitive sensor, is in motion based on sensed intermittent changes in the capacitance. Various other methods of operation are disclosed.

Abstract: A capacitive sensing system includes a controller, a node connected to one side of a capacitance, the controller configured to measure the capacitance by measuring a time for a voltage across the capacitance to reach a predetermined reference voltage, and the controller causing the time period for capacitance measurements to vary even when the capacitance is constant.