Abstract: Methods, systems and devices are described for detecting a measurable capacitance using sigma-delta measurement techniques. According to various embodiments, a voltage is applied to the measurable capacitance using a first switch. The measurable capacitance is allowed to share charge with a passive network. If the charge on the passive network is past a threshold value, then the charge on the passive network is changed by a known amount for a sufficient number of repetitions until the measurable capacitance can be detected. Such a detection scheme may be readily implemented using conventional components, and can be particularly useful in sensing the position of a finger, stylus or other object with respect to a button, slider, touchpad or other input sensor.

Abstract: A capacitive sensor with ratiometric voltage references includes a voltage source, a charge transfer switch, an integrating capacitor, and a comparator. The voltage source is configured to generate a first voltage reference and a second voltage reference in response to a supply voltage, where the first voltage reference changes proportionally to the second voltage reference in response to a change in the supply voltage. The charge transfer switch is coupled to the integrating capacitor to distribute charge between a sensing capacitor and the integrating capacitor, where the charge is accumulated in response to the first voltage reference. The comparator is coupled to the second voltage reference and the integrating capacitor to compare a voltage on the integrating capacitor against the second voltage reference.

Abstract: Systems and methods are provided for sensing or measuring capacitive or inductive reactance or changes in reactance in which the sensed reactance is coupled with a known resistance in a sensor circuit and a start signal is provided to the sensor circuit, and a programmable delay line is used to generate a programmable delay signal. The outputs of the programmable delay and the sensor circuits are compared to ascertain which transitions first, and the programmable delay value is adjusted in successive approximation fashion to identify a programmable delay that best represents the delay time of the sensor circuit from which the sensed reactance value can be determined.

Abstract: A method of capacitance-to-voltage conversion with an external sensor capacitor (CP) and a capacitance-to-voltage converter (14) implemented on an integrated readout circuit that includes a reference capacitor (CR), a sampling capacitor (CS) and a sampling amplifier (22) and which has input terminals (16) to which the sensor capacitor (CP) is connected. The method comprises the steps of a) applying a reference voltage (Vref) to the series connected sensor capacitor (CP) and reference capacitor (CR) and charging the sampling capacitor (CS) to the potential at the interconnection node (A) between the sensor capacitor (CP) and the reference capacitor (CR), b) connecting the sampling capacitor (CS) to inputs of the sampling amplifier.

Abstract: A capacitive occupant detection system has an oscillator and an electrode operatively coupled to the oscillator, to which the oscillator applies an oscillating voltage signal. In response to the oscillating voltage being applied, an electric current is caused to flow in the electrode, the current being responsive to an electric-field-influencing property of an object or occupant proximate to the electrode. The current caused to flow in the electrode has a first current component in phase with the oscillating voltage signal and a second current component 90°-phase-offset with respect to the oscillating voltage signal. A sensing circuit is operatively coupled to the electrode and to the oscillator so as to generate a first signal indicative of the first current component and a second signal indicative of the second current component.

Abstract: A method of capturing user control inputs for an electronic device comprises sampling an input measurement signal at a capacitive input sensor of the electronic device to capture user control inputs for operating the electronic device. Electromagnetic interference affecting the sampling of the input measurement signal is electronically neutralized.

Abstract: A capacitance detection circuit that compensates for the fluctuation of a reference voltage with a simple structure. A C-V circuit for a sensor element generates a detection signal by amplifying a capacitance change value of the sensor element by a predetermined gain based on a reference voltage. A voltage compensation circuit, which is connected to the C-V circuit and supplies a reference voltage to the C-V circuit, reduces the gain relative to a deviation amount when the reference voltage fluctuates by a predetermined deviation amount.

Abstract: The present invention relates to a capacitive MEMS sensor device for sensing a mechanical quantity.

Abstract: A measuring apparatus is provided which has least one voltage source for providing a supply voltage for a semiconductor device to be tested, at least one first tester channel connected to the supply voltage source via a first RC element having a first resistor and a first capacitor connected in series therewith, wherein the first tester channel is adapted for the temporally resolved measurement of a charging voltage of the first capacitor.

Abstract: A sensor apparatus includes a sensor circuit and a nonlinear signal processing circuit. The sensor circuit detects a physical quantity and outputs a detection signal indicative of the detected physical quantity. The signal processing circuit includes a logarithmic converter, an analog-to-digital converter, and an antilogarithmic converter. The logarithmic converter produces a logarithm signal corresponding to a logarithm of the detection signal. The analog-to-digital converter digitalizes the logarithm signal. The antilogarithmic converter produces an antilogarithmic signal corresponding to an antilogarithm of the digitalized logarithm signal.

Abstract: A capacitive physical quantity sensor includes a sensor element and a detecting element. The sensor element includes first and second fixed electrodes facing a movable electrode. A first voltage is applied to the first fixed electrode and a second voltage is applied to the second fixed electrode. The detecting circuit includes a capacitance-voltage conversion circuit, in which an operational amplifier, a capacitor and a switch including a P-channel MOS transistor and a N-channel MOS transistor are disposed. The transistors have a back gate potential, which is approximately equal to an average voltage of the first voltage and the second voltage.

Abstract: A circuit includes a first capacitor having first and second capacitive sensing strips positioned on first and second sliding portions of the slider type mobile device. In the closed position, the first and second capacitive sensing strips overlap one another and in an open position the first and second capacitive sensing strips have no overlap with one another. A voltage divider having a voltage VIN(+) comprised of a first resistor network is coupled with the first capacitor. A voltage comparator having two inputs VIN(+) and VIN(?) is used to determine a high or low state. A second resistive network is used to set VIN(?). The voltage comparator will return a digital high condition indicative of the slider being in the open position when VIN(+) is greater than VIN(?) and a digital low condition indicative of the slider being in the closed position when VIN(+) is less than VIN(?).

Abstract: In a capacitive sensing device for detecting a change in capacitance of an electrode which is caused by contact with a human body, the improvement of determination speed may be enabled. M (m is an integer satisfying n?m?2) electrodes are selected from n (n is an integer equal to or larger than two) electrodes. Capacitors connected to the m electrodes are discharged in parallel during a predetermined period, and then charged. During the charging period, a potential of each of the m electrodes is compared with a reference potential. A difference between capacitance values of the capacitors connected to the m electrodes is determined based on a result obtained by the comparison between the m electrodes.

Abstract: An improved system and method of performing capacitance measurements that provides a fast digital response and a reduced output error. The capacitance measurement system includes a circuit configuration that has a variable capacitor and at least one reference capacitor connected to one another at a common node, which in turn is connected to the input of an analog-to-digital converter. The circuit configuration further includes an array of switches coupled between the variable and reference capacitors and the supply voltage, a reference voltage, and ground, respectively. The switched variable and reference capacitors are employed in conjunction with the A-to-D converter to perform, at the common node, a plurality of direct voltage measurements for use in generating an expression defining the capacitance of the variable capacitor.

Abstract: An apparatus includes a first capacitive sensor connected to a first supply voltage, a second capacitive sensor connected to a second supply voltage, a sensing circuit for producing a sense voltage in response to current flowing in the first and second capacitive sensors, a first mixer for combining the sense voltage with a first reference voltage to produce a first signal representative of in-plane displacement between electrodes of the first and second capacitive sensors, and a second mixer for combining the sense voltage with a second reference voltage to produce a second signal representative of out-of-plane displacement between the electrodes of the first and second capacitive sensors.

Abstract: A level shift IC (3b) of a power supply/shutoff section (3) is operable, when a shutoff signal (Sa) is input from a timer circuit (8) for a time T during an ON state of a discharge lamp (7), to turn off a MOSFET (3a) so as to shut off power supply to a smoothing capacitor (4). When a detection signal (Sb) of a capacitor voltage is lowered to a value less than a reference voltage Vr1 during input of the shutoff signal (Sa), an output of a comparator (10) is changed from an H level to an L level in an inverted manner. In conjunction with this change, respective outputs of an auxiliary control circuit (12) and a NOT element (12a, 12b) are changed from an L level to an H level in an inverted manner. As a result, a current flows from the NOT element (12a) to an LED (13b) through a resistor (13a) to turn on the LED (13b). Thus, a life end of the smoothing capacitor 4 is annunciated, and a main control circuit (6) is operable to suppress an output of an inverter main circuit (5).

Abstract: A fluid measuring device for use in a fluid storage tank, comprising a logic operation unit, a capacitive sensor, and a capacitance sensing circuit; wherein the capacitance sensing circuit is driven by the constant current input to perform the detection of the capacitance value of the capacitive sensor, then perform the conversion from the capacitance value into the signal on the physical characteristics of the fluid body by the logic operation unit. The signal on the physical characteristics can include any of the concentration, density, and surface level of the fluid body. Furthermore, the capacitive sensor can further comprise a reference capacitor and a detection capacitor for detecting the fluid, the latter capacitance is obtained from a differential circuit of the capacitance sensing circuit.

Abstract: A capacitive sensor for detecting a physical quantity includes a sensor element and a detecting circuit. The sensor element includes a movable electrode and a fixed electrode. A periodic voltage is applied to the fixed electrode. A high-voltage generating circuit applies a diagnostic voltage to an input side of a C-V conversion circuit so as to diagnose a sticking of a foreign object between the movable electrode and the fixed electrode. The C-V conversion circuit includes a diagnostic switch, which is opened in a diagnostic mode. The periodic voltage in the diagnostic mode is larger than the periodic voltage in a normal measuring mode.

Abstract: Disclosed is a method for producing a synthetic resin mold package at high yield from which package a pair of the surface of an internal device is exposed. A to-be-exposed part of the surface of the internal device composed of an insulating substrate (2) and thin film electrodes (4, 5) and an insulating protective film (6) formed on the substrate is covered with a coating agent (42), and a die pad portion (8) is bonded to the back surface of the internal device. After placing the thus-obtained structure in a mold consisting of a lower mold (46) and an upper mold (48), a pin (50) is inserted into the mold so that the front end of the pin is pressed against the die pad portion (8), thereby keeping the surface of the coating agent (42) pressed against the inner surface of the upper mold (48). Then, a synthetic resin (52) is injected into the mold and cured therein. The thus-obtained resin sealed body is taken out from the mold, and the coating agent (42) is removed from the resin sealed body.

Abstract: A touch sensor assembly. The touch sensor assembly may include a housing, at least one touch sensor and a sensor cover. The sensor cover may identify a touch area associated with each touch sensor. The housing may form a water tight cavity for the sensor cover and the touch sensor when coupled to an housing cover. A raised dome may be provided, e.g. on the sensor cover or another element, to provided tactile feed back. LEDs may be provided for illuminating the touch areas and/or sensing ambient light. A controller may control the illumination level of the LEDs in response to sensed ambient light. Adjacent key suppression algorithms are also provided.

Abstract: An apparatus for determining capacitance variation in an integrated circuit, includes at least two capacitances, a stimulus provided to the at least two capacitances, and a first logic element coupled to the stimulus and the at least two capacitances, the first logic element configured to switch state upon a state transition of the stimulus when the at least two capacitances differ in value by a predetermined amount.

Abstract: Capacitance measurement apparatus that enhances the sensitivity and accuracy of capacitive transducers, proximity sensors, and touchless switches. Each of two capacitors (C1, C2) under measurement has one end connected to ground and is kept at substantially the same voltage potential by operational amplifier (A1) or amplifiers (A0, A1) using negative feedback. The apparatus is driven by a periodic e.g. sinusoidal signal source (G1) or sources (G1, G2) and includes a difference amplifier (A2) operative to produce an electrical signal having a linear relationship with a specified arithmetic function of the capacitances of the two capacitors (C1, C2). A touchless switch is implemented using the capacitance measurement apparatus. The touchless switch includes two sensor electrodes (E1, E2) that correspond to the two capacitors (C1, C2) under measurement and in one embodiment has a front surface in the form of a container.

Abstract: A capacitance/voltage conversion circuit converts the difference in electrostatic capacitance between a first capacitor and a second capacitor into a voltage. With such an arrangement, a first voltage applying unit applies a power supply voltage Vdd to the first capacitor during a first state, and applies the ground voltage 0V to the first capacitor during a second state. A second voltage applying unit applies the ground voltage 0V to the second capacitor during the first state, and applies the power supply voltage Vdd to the second capacitor during the second state. A first sample hold circuit averages the voltage at the first capacitor and the voltage at the second capacitor in the first state by turning on a first switch and a second switch, and holds the voltage thus averaged as a first detection voltage Vdet1.

Abstract: A capacitive sensor includes a sensing electro, control unit, first and second comparator wherein the sensing electro includes a first and a second conduct ports. A positive input terminal of the first comparator and a negative input terminal of the second comparator are coupled to the first conduct port. A positive input terminal of the second comparator and a negative input terminal of the first comparator are coupled to the second conduct port. The first and second comparators respectively output first and second comparing signals according to voltages of the positive and the negative terminals thereof. The control unit charges the first conduct port and discharges the second conduct port when the first and second comparing signals correspondingly are in first and second logic states. The control unit is operable on the contrary when the first and second comparing signals are in opposition to the abovementioned description.

Abstract: Systems and methods are provided for sensing or measuring capacitive or inductive reactance or changes in reactance in which the sensed reactance is coupled with a known resistance in a sensor circuit and a start signal is provided to the sensor circuit, and a programmable delay line is used to generate a programmable delay signal. The outputs of the programmable delay and the sensor circuits are compared to ascertain which transitions first, and the programmable delay value is adjusted in successive approximation fashion to identify a programmable delay that best represents the delay time of the sensor circuit from which the sensed reactance value can be determined.

Abstract: An embodiment of the present invention relates to a alignment measurement system for measuring alignment between a plurality of chips of a device, the chips being assembled in a three-dimensional stacking configuration and equipped with at least an integrated capacitive sensor, including a multiple-capacitor structure integrated in the capacitive sensor, at least a sensing circuit connected to the multiple-capacitor structure which issues an output voltage, proportional to a variation of a capacitive value of the multiple-capacitor structure of the integrated capacitive sensor of the device and corresponding to a measured misalignment between the chips of the device.

Abstract: A substrate forming a sensor element is connected to a non-inverting input terminal of an operational amplifier, and a common voltage is applied thereto from a reference voltage supply circuit to fix them to the same potential. Thus, the impedances of the non-inverting input terminal and of the inverting input terminal of the operational amplifier are matched with respect to the power source. Therefore, noise superposed on a power source line can be greatly decreased by noise-removing characteristics determined by CMRR characteristics of the operational amplifier. As a result, a capacitive-type acceleration sensor exhibits sensor characteristics of frequency noise suppressing effect.

Abstract: Embodiments of water activated survival lamp units for mounting to a flotation device above and in proximity to the water line are disclosed. In one exemplary embodiment, the survival lamp unit has a light source including a LED array having a plurality of semi conducting light emitting chips encased in a unitary lens structure through which the semi conducting light emitting chips output light. The exemplary survival lamp unit further includes a water responsive actuator for controlling the operation of the light source, responsive to a momentary contact with a coherent body of water for actuating the light source for an operative cycle of a time period largely exceeding a duration of the momentary contact. In some implementations, when the survival lamp unit is actuated, it emits either fixed light or flashing light in generally all directions of the upper hemisphere.

Abstract: An improved system and method of performing capacitance measurements that provides a fast digital response and a reduced output error. The capacitance measurement system includes a circuit configuration that has a variable capacitor and at least one reference capacitor connected to one another at a common node, which in turn is connected to the input of an analog-to-digital converter.

Abstract: A sensor device and method for detecting the presence of an analyte in a fluid solution are disclosed. The sensor device system can comprise a substrate and an array of free-standing nanowires attached to the substrate. The array can include individual free-standing nanowires wherein each of the individual free-standing nanowires have a first end and a second end. The first end can, in some embodiments, be attached to the substrate and the second end unattached to the substrate. Such individual free-standing nanowires are configured for electrical communication with other individual free-standing nanowires through the first end. A chip or computer can be electrically coupled to the array of free-standing nanowires for receiving electrical information from the array of free-standing nanowires. In some embodiments a power source can be used to send current through the nanowire array.

Abstract: A current measurement circuit to measure the output of a power supply transformer includes a simulation capacitor having a capacitance proportional to a parasitic capacitance of the transformer. The first electrode of the capacitor is coupled to an output winding of the transformer and the second electrode is coupled to a first node, with a second sense resistor coupled between the first node and ground so that current flowing through the simulation capacitor flows through the second sense resistor. Current flowing through a first sense resistor coupled to a second node and to ground has a component representative of the output current of the power supply and a component representative of the parasitic current. A differential amplifier coupled at an inverting input to the first node and at a non-inverting input to the second node generates an output signal that is proportional to the output current of the power supply.

Abstract: A capacitive occupant detection system has an oscillator and an electrode operatively coupled to the oscillator, to which the oscillator applies an oscillating voltage signal. In response to the oscillating voltage being applied, an electric current is caused to flow in the electrode, the current being responsive to an electric-field-influencing property of an object or occupant proximate to the electrode. The current caused to flow in the electrode has a first current component in phase with the oscillating voltage signal and a second current component 90°-phase-offset with respect to the oscillating voltage signal. A sensing circuit is operatively coupled to the electrode and to the oscillator so as to generate a first signal indicative of the first current component and a second signal indicative of the second current component.

Abstract: A testing circuit for an interface includes a load feeding circuit and a voltage testing circuit. The load feeding circuit includes a resistance-regulating unit, a first comparator, a pass element, and a capacitor. The resistance-regulating unit is connected to a positive input of the first comparator. A negative input of the first comparator is connected to the capacitor and a first terminal of the pass element. An output of the first comparator is connected to a second terminal of the pass element. A third terminal of the pass element is connected to the interface. The voltage testing circuit includes a second comparator and a display member connected to the second comparator. The voltage of the interface and a reference voltage are input to inputs of the second comparator, and the second comparator outputs a signal to control the display member to display a comparison result.

Abstract: Described are quality control methods and devices for the reproducible manufacturing and integrity monitoring of polymers on electrochemical synthesis and detection chips. The devices and methods allow for simultaneous manufacturing and synthesis of polymers.

Abstract: A capacitance difference detecting circuit has timing generator that outputs a current switching pulse signal for controlling a switching operation of a current switching circuit, outputs a gate pulse signal for controlling a chopper amplifier so that the chopper amplifier detects the first charging voltage when a first variable capacitor is charged by a first charging voltage and detects a second charging voltage when a second variable capacitor is charged by a second charging voltage, outputs a first sample pulse signal for controlling a first sampling and holding circuit so that the first sampling and holding circuit samples and holds the output signal of the chopper amplifier when the first charging voltage is detected, and outputs a second sample pulse signal for controlling the second sampling and holding circuit so that the second sampling and holding circuit samples and holds the output signal of the chopper amplifier when the second charging voltage is detected.

Abstract: A capacitive sensing system (100) can connect groups of capacitive sensors (112-1 to 112-N) to a common node (106) to detect change in capacitance. States of a set of capacitive sensors (112-1 to 112-N) can thus be scanned faster than approaches that scan such sensors one-by-one. Faster scanning can allow for reduced power consumption in applications that only periodically scan the set of capacitive sensors (112-1 to 112-N).

Abstract: This disclosure describes a capacitive interface circuit for a low power system. The capacitive interface circuit is configured to achieve very low noise sensing of capacitance-based transducers, such as a micro-electro-mechanical system (MEMS)-based sensor, with high resolution and low power. The capacitive interface circuit uses a differential amplifier and correlated triple sampling (CTS) to substantially eliminate, or at least reduce, kT/C noise, as well as amplifier offset and flicker (1/f) noise, from the output of the amplifier. The capacitive interface circuit may further include an output stage that reduces glitching, i.e., clock transients, in the output signal by allowing transients in the amplifier output to settle. In this manner, the circuit can be used in a low power system to produce a stable, low-noise output.

Abstract: A two phase, second order capacitance-to-digital (CD) modulator includes a first stage sigma-delta integrator that forms charge packets as a function of sensor capacitance during an auto-zero phase and integrates the packets during an integration phase to produce an output voltage. The first stage integrator holds its output voltage during the auto-zero phase, so that a second stage sigma-delta integrator can sample the first stage output voltage during the auto-zero phase and integrate the sampled voltage during the integration phase.

Abstract: Capacitance measurement apparatus that enhances the sensitivity and accuracy of capacitive transducers, proximity sensors, and touchless switches. Each of two capacitors (C1, C2) under measurement has one end connected to ground and is kept at substantially the same voltage potential by operational amplifier (A1) or amplifiers (A0, A1) using negative feedback. The apparatus is driven by a periodic e.g. sinusoidal signal source (G1) or sources (G1, G2) and includes a difference amplifier (A2) operative to produce an electrical signal having a linear relationship with a specified arithmetic function of the capacitances of the two capacitors (C1, C2). A touchless switch is implemented using the capacitance measurement apparatus. The touchless switch includes two sensor electrodes (E1, E2) that correspond to the two capacitors (C1, C2) under measurement and in one embodiment has a front surface in the form of a container.

Abstract: A capacitance-to-digital (CD) modulator converts capacitance of a differential pressure sensor to a pulse code modulation output signal. The first stage of the CD modulator is a sigma-delta integrator having an auto-zero capacitor connected between an integrator input node and an amplifier input. During an auto-zero phase, a feedback capacitor is connected between the amplifier input and output, and the auto-zero capacitor stores a voltage that is a function of leakage resistance of the sensor capacitor connected to the integrator input node. During an integration phase, the feedback capacitor is connected to the integrator input node. If an overpressure/short circuit condition exists, the stored voltage on the auto-zero capacitor induces a current to flow to the feedback capacitor to drive the integrator to saturation and suppress foldback anomaly.

Abstract: A device to determine an absolute rotation angle of a rotary shaft (14) has a first measurement arrangement (10) to measure a rotation angle in a restricted first measurement range, and a second measurement arrangement (12) to determine an absolute angle range. The first measurement arrangement (10) includes a rotor (16), coupled to the rotary shaft (14), and a carrier which is stationary in relation to the rotor (16). Coded zones (18) are arranged either on the rotor (16) or on the carrier. The coded zones (18) are distributed in the peripheral direction with respect to the rotary shaft (14). At least one first sensor (20) is arranged on the carrier or on the rotor (16), respectively. The first sensor (20) detects a coding of the coded zones (18) when the rotary shaft (14) rotates.

Abstract: A differential capacitor one terminal capacitor interface circuit for sensing the capacitance of first and second capacitors includes a differential integrating amplifier having first and second summing nodes and an input common mode voltage; and a switching circuit for charging a first capacitor of said differential one terminal capacitor to a first voltage level and a second capacitor of said differential one terminal capacitor to a second voltage level in a first phase, in a second phase connecting said first capacitor to said first summing node and said second capacitor to said second summing node of said amplifier to provide first and second output changes substantially representative of the difference between said first and second voltage levels and said input common mode voltage, in a third phase charging said first capacitor to said second voltage level and said second capacitor to said first voltage level, and in a fourth phase connecting said first capacitor to said second summing node and said seco

Abstract: Methods, systems and devices are described for detecting a measurable capacitance using sigma-delta measurement techniques. According to various embodiments, a voltage is applied to the measurable capacitance using a first switch. The measurable capacitance is allowed to share charge with a passive network. If the charge on the passive network is past a threshold value, then the charge on the passive network is changed by a known amount for a sufficient number of repetitions until the measurable capacitance can be detected. Such a detection scheme may be readily implemented using conventional components, and can be particularly useful in sensing the position of a finger, stylus or other object with respect to a button, slider, touchpad or other input sensor.

Abstract: Methods and systems are described for efficiently detecting an object. The system includes at least one electrode for measuring a displacement current. The at least one electrode is coupled to a floating ground configuration provided by an op-amp, where the inverting node of the op-amp is coupled to electrode and the non-inverting node is coupled to a signal generator. The system may include a single capacitance sensor for detecting an object. Systems may include a plurality of capacitance sensors in an array configuration for detecting an object.

Abstract: A capacitive sensor for detecting a physical quantity includes a sensor element and a detecting circuit. The sensor element includes a movable electrode and a fixed electrode. A periodic voltage is applied to the fixed electrode. A high-voltage generating circuit applies a diagnostic voltage to an input side of a C-V conversion circuit so as to diagnose a sticking of a foreign object between the movable electrode and the fixed electrode. The C-V conversion circuit includes a diagnostic switch, which is opened in a diagnostic mode. The periodic voltage in the diagnostic mode is larger than the periodic voltage in a normal measuring mode.

Abstract: A one terminal capacitor interface circuit for sensing the capacitance of a capacitor includes a differential integrating amplifier having an input common mode voltage and two summing nodes whose voltage is substantially equal to the input common mode voltage, a switching circuit for charging the capacitor to a first voltage level in a first phase, connecting, in a second phase, the capacitor to one of the summing nodes of the differential amplifier to provide a first output change substantially representative of the difference between the first voltage level and the input common mode voltage, and also representative of the capacitor; charging the capacitor to a second voltage level in a third phase, and connecting, in a fourth phase, the capacitor to the other summing node of the differential amplifier to provide a second output change substantially representative of the difference between the second voltage level and the input common mode voltage, and also representative of the capacitor; the combined first

Abstract: A pressure transmitter having a capacitance-to-digital modulator produces an output as a function of sensor capacitance and a reference capacitance. Transmitter also includes a sensor failure mode detector produces an output signal and identifies failure modes of the sensor capacitance and reference capacitance.

Abstract: A CBCM circuit is capable of separately measuring each component of a measuring target capacitance. A node (N1) is electrically connected to a terminal (P2) between the drains of PMOS and NMOS transistors (MP2, MN2). As a target capacitance forming part, a coupling capacitance (Cc) is formed between the node (N1) and a node (N2). The node (N2) is connected to a pad (58) through the terminal (P2) and an NMOS transistor (MN3), and a node (N3) is connected to a terminal (P3) between the drains of PMOS and NMOS transistors (MP1, MN1). A reference capacitance (Cref) is formed at the node (N3) as a dummy capacitance. Currents (Ir, It) supplied from a power source to the nodes (N3, N1) are measured with current meters (61, 62), respectively and a current (Im) induced from the node (N2) and flowing to a ground level is measured with a current meter (63).

Abstract: Sensor circuits for the measurement of small variations in the value of a sensing capacitor. An alternating voltage excites the sensing capacitor a predetermined frequency whereby the voltage on the sensing capacitor reverses polarity. This voltage on the sensing capacitor is sampled each time the voltage reverses polarity. An accumulator accumulates the sampled charges from the sensing capacitor. An output signal that represents the charge in the charge accumulating means indicates the measured capacitance.

Abstract: A circuit for detecting a difference in capacitance between a first capacitor and a second capacitor provided in a sensor includes an oscillator configured to generate an oscillating signal, a phase comparator coupled to the oscillator to output a signal responsive to a phase difference between the oscillating signal delayed by the first capacitor and the oscillating signal delayed by the second capacitor, an integration circuit coupled to the phase comparator to output an integrated signal made by integrating the signal responsive to the phase difference over a time period equal to a predetermined number of cycles of the oscillating signal, and a sample-and-hold circuit coupled to the integration circuit to output a signal made by sampling and holding the integrated signal at substantially an end of the time period.