Abstract: A capacitive touch sensor providing an automatic switch-off function for an apparatus in which the sensor is incorporated is provided. The sensor comprises a sensing element coupled to a capacitance measurement circuit for measuring the capacitance of the sensing element. A control circuit is operable to determine from the capacitance measurement whether an object is in proximity with the sensor. The determined presence of an object may be used to toggle a function of the apparatus. Furthermore, when it is determined that an object has not been in proximity with the sensor for a predetermined time duration, an output signal for switching off the apparatus is provided. The predetermined time duration may be selected from a number of predefined time durations, or may be programmed using an resistor-capacitor network. Pulses may be applied to the control circuit to override features of the automatic switch-off functionality.

Abstract: Disclosed is a charge transfer-based circuit arrangement for capacitive proximity switches comprising a capacitive sensor element (C3), the capacity of which changes according to the actuation mode. The circuit arrangement includes a central capacitor (C2), a first controllable connecting means (D2) that impinges the capacitive sensor element with a charging voltage (U3) according to a triggering signal, and a second controllable connecting means (T1) which connects the capacitive sensor element to the central capacitor according to the triggering signal in order to transfer the charge from the capacitive sensor element to the central capacitor. The charging voltage can be an AC voltage while the connecting means can be impinged upon by the AC voltage in such a way that the first connecting means or the second connecting means is alternately conductive.

Abstract: Methods, systems and devices are described for detecting a measurable capacitance using charge transfer techniques. According to various embodiments, a charge transfer process is performed for two or more times. During the charge transfer process, a pre-determined voltage is applied to the measurable capacitance, and the measurable capacitance is then allowed to share charge with a filter capacitance through a passive impedance that remains coupled to both the measurable capacitance and to the filter capacitance throughout the charge transfer process. The value of the measurable capacitance can then be determined as a function of a representation of a charge on the filter capacitance and the number of times that the charge transfer process was performed. 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 an input sensor.

Abstract: A self-calibration system includes a variable current source to generate a default source current for charging a capacitive load, and a load charge calibrator to detect a voltage associated with the capacitive load when charged by the default source current, and to generate a current control feedback according to the detected voltage and a desired charged voltage of the capacitive load, the current control feedback to indicate to the variable current source a charge current capable of charging the capacitive load to the desired charged voltage.

Abstract: A switched capacitance detection circuit is responsive to changes in the fringing capacitance of a capacitive proximity sensor having at least one capacitive sensor element. In cases where the sensor has a single sensor element, the switching frequency of the detection circuit is controlled to maintain measurement accuracy in the presence of sensor moisture while minimizing power consumption and electromagnetic radiation. In cases where the sensor has multiple sensor elements, the capacitance values for each sensor element are differenced, absolute-valued and summed to form an output in which common-mode effects due to sensor moisture, temperature and sensor aging are canceled out.

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, systems and devices are described for determining a measurable capacitance for proximity detection in a sensor having a plurality of sensing electrodes and at least one guarding electrode. A charge transfer process is executed for at least two executions. The charge transfer process includes applying a pre-determined voltage to at least one of the plurality of sensing electrodes using a first switch, applying a first guard voltage to the at least one guarding electrode using a second switch, sharing charge between the at least one of the plurality of sensing electrodes and a filter capacitance, and applying a second guard voltage different from the first guard voltage to the at least one guarding electrode. A voltage is measured on the filter capacitance for a number of measurements equal to at least one to produce at least one result to determine the measurable capacitance for proximity detection.

Abstract: For measuring unknown capacitances, which exist in capacitive sensors, such as pressure, moisture, inclination sensors and the like, the invention proposes a capacitance measurement method, in which a capacitance to be measured is charged and discharged across a resistor and the charging or discharging time up to a preset voltage value is measured and in which the charging/discharging times of a known reference capacitance and stray capacitances are measured across a resistor. The invention also proposes a circuit for measuring an unknown capacitance to be measured and having a voltage source, a resistor for charging or discharging at least the measuring capacitor, at least one switch for connecting and disconnecting the measuring capacitor with respect to the voltage supply and a time measuring device, in which switches are provided for connecting and disconnecting the measuring capacitor and at least one reference capacitor with respect to the circuit.

Abstract: An arrangement for testing a plurality of capacitances in a capacitance array of an integrated circuit includes a power supply and a means for cyclically charging and discharging at least one of the capacitances. In this arrangement, the cycle frequency is dependent on the value of the capacitance. The cycle frequency or a quantity characteristic associated therewith is measured by a means to ascertain a value of the capacitance under test.

Abstract: A capacitor connected to a voltage source is charged during a charging phase up to a voltage value, and during a discharging phase the capacitor is discharged via a coupling element connected to the flame sensor. The period for the charging or discharging phase of the capacitor respectively is selected in this case as a function of the characteristics of the flame sensor, especially of its impedance. For flame monitoring the charging and discharging of the capacitor is repeated cyclically, with the voltage signal obtained in this way being evaluated in single-channel mode with the aid of a threshold value.

Abstract: Methods, systems and devices are described for detecting a measurable capacitance using charge transfer techniques that can be implemented with many standard microcontrollers, and can share components to reduce device complexity and improve performance. In the various implementations of this embodiment, the passive network used to accumulate charge can be shared between multiple measurable capacitances. Likewise, in various implementations a voltage conditioning circuit configured to provide a variable reference voltage can be shared between multiple measurable capacitances. Finally, in various implementations a guarding electrode configured to guard the measurable capacitances can be shared between multiple measurable capacitances. In each of these cases, sharing components can reduce device complexity and improve performance.

Abstract: A system for determining the logic state of a resistive memory cell element, for example an MRAM resistive cell element. The system includes a controlled voltage supply, an electronic charge reservoir, a current source, and a pulse counter. The controlled voltage supply is connected to the resistive memory cell element to maintain a constant voltage across the resistive element. The charge reservoir is connected to the voltage supply to provide a current through the resistive element. The current source is connected to the charge reservoir to repeatedly supply a pulse of current to recharge the reservoir upon depletion of electronic charge from the reservoir, and the pulse counter provides a count of the number of pulses supplied by the current source over a predetermined time. The count represents a logic state of the memory cell element.

Abstract: An apparatus and method for operation of a differential capacitance transducer, including generating substantially opposing polarity excitation drive signals by operation of a pair of drive signal generators, applying the excitation drive signals to a pair of sense capacitors of a differential capacitance sensor, sensing a differential capacitance at a common junction between the pair of sense capacitors; and individually controlling the drive signal generators for trimming a null bias of the sense capacitor pair at the common junction.

Abstract: An apparatus and method for measuring a capacitance on the sensor element using two charge rates. The two charge rates may be two charging rates, or alternatively, two discharging rates for discharging the sensor element. Alternatively, both the two charging and discharging rates may be used to measure the capacitance. The method may be performed by charging a sensor element of a sensing device for a fixed time at the first charging rate, and charging the sensor element at the second charging rate to reach a threshold voltage after charging the sensor element for the fixed time. The method may also be performed by discharging the sensor element for a fixed time at the first discharging rate, and discharging the sensor element at the second discharging rate to reach a threshold voltage after discharging the sensor element for the fixed time.

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: 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 capacitance measurement circuit includes a current source, a switch, and a comparator. The current source is coupled to drive a current through a circuit node. The switch is coupled to the circuit node to switch the current into a device under test (“DUT”) capacitor. The comparator includes first and second input ports. The comparator is coupled to compare a first voltage received on the first input port against a reference voltage received on the second input port. The first voltage is related to the current driven through the circuit node, a frequency at which the switch is switched, and a capacitance of the DUT capacitor.

Abstract: An apparatus that may be used to sense capacitance, as well as other functions. The apparatus includes a comparator circuit with hysteresis, a capacitor, and a current driver. The comparator circuit with hysteresis includes a first input and an output. The capacitor is coupled to the first input of the comparator circuit with hysteresis. The current driver is coupled to the output of the comparator circuit with hysteresis and to the capacitor. The current driver reciprocally sources and sinks a drive current through a terminal of the capacitor to oscillate a voltage potential at the terminal of the capacitor between a low reference potential and a high reference potential. The current driver is responsive to the output of the comparator circuit with hysteresis.

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, 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 capacitor apparatus according to the present invention is configured to charge electric charge in capacitors C1 and C2 and discharge electric charge from the capacitors C1 and C2 at normal operation time. The capacitor apparatus includes an internal resistance detection means 2 for detecting the internal resistance value of the capacitors C1 and C2 and an inter-capacitor charging/discharging control means 1 for controlling charging/discharging operation between the capacitors C1 and C2. When the internal resistance detection means 2 detects a resistance value more than a predetermined value, the inter-capacitor charging/discharging control means 1 performs charging/discharging control between the capacitors C1 and C2 to cause the capacitors C1 and C2 to self-heat.

Abstract: Methods, systems and devices are described for determining a measurable capacitance for proximity detection in a sensor having a plurality of sensing electrodes and at least one guarding electrode. A charge transfer process is executed for at least two executions. The charge transfer process includes applying a pre-determined voltage to at least one of the plurality of sensing electrodes using a first switch, applying a first guard voltage to the at least one guarding electrode using a second switch, sharing charge between the at least one of the plurality of sensing electrodes and a filter capacitance, and applying a second guard voltage different from the first guard voltage to the at least one guarding electrode. A voltage is measured on the filter capacitance for a number of measurements equal to at least one to produce at least one result to determine the measurable capacitance for proximity detection.

Abstract: A surface capacitance sensor system is implemented as an array of sensor electrodes near the surface of the integrated circuit and an array of stimulus electrodes below the sensor electrodes. Rows of stimulus electrodes are driven by sources while the voltages at the respective sensor electrodes are measured. Voltage measurements at each sensor electrode allow the surface capacitance at each sensor electrode location to be determined. The capacitance data is used to determine the positions of target electrodes above the array surface as required in the location fingerprint artifacts.

Abstract: A method and apparatus for determining capacitance of wires in an integrated circuit is described. The capacitance information derived according to the invention can be used, for example, to calibrate a parasitic extraction engine or to calibrate an integrated circuit fabrication process. The capacitance information can also be used for timing and noise circuit simulations, particularly for deep sub-micron circuit design simulations. Briefly, the invention allows measurement of both total capacitance of a line and cross coupling capacitance between two lines by applying predetermined voltage signals to specific circuit elements. The resulting current allows simple computation of total capacitance and cross coupling capacitance. Multiple cross coupling capacitance can be measured with a single device, thus improving the art of library generation, and the overall method is free of uncertainties related to transistor capacitance couplings.

Abstract: When an array of proximity sensors is used as a keyboard, it can provide an ambiguous output if a user's finger overlaps several keys or if liquid is spilled on the keyboard. This ambiguity is reduced by an iterative method that repeatedly measures a detected signal strength associated with each key, compares all the measured signal strengths to find a maximum, determines that the key having the maximum signal strength is the unique user-selected key and then suppresses or ignores signals from all other keys as long as the signal from the selected key remains above some nominal threshold value.

Abstract: Apparatus and systems, as well as methods and articles, may operate to transmit an initial pulse to a directional coupler, where the initial pulse has an initial amplitude and a timed overshoot of a selected duration. Further activities may include stepping down the initial amplitude to an amplitude approximately equal to the initial amplitude times a mode reflection coefficient squared. A tuning stub may be coupled to a charge line to transmit the initial pulse, and decoupled from the charge line to refrain from receiving an echo pulse associated with the initial pulse.

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: An electrostatic capacitance detection device including an electrostatic capacitance detection element arranged in a matrix form; a row line arranged in each row for selecting a relevant electrostatic capacitance detection element arranged in a relevant row; an output line arranged in each column for outputting a signal from a relevant electrostatic capacitance detection element arranged in a relevant column, wherein each electrostatic capacitance detection element is provided with a row selection element that controls the outputting of the signal of the relevant electrostatic capacitance detection element to the relevant output line based on the signal from the relevant row, and the signal from the relevant electrostatic capacitance detection element, which is caused to be in a selection state based on the signal from the relevant row line, is outputted to the output line arranged in the relevant electrostatic capacitance detection element.

Abstract: A method for determining capacitance includes alternately charging a capacitor to a first voltage and discharging the capacitor to a second voltage, generating an output signal having a frequency that is a function of a time period, and determining the capacitance based on the frequency of the output signal. The time period is selected from at least one of: (a) a time period needed to charge the capacitor from the second voltage to the first voltage and (b) a time period needed to discharge the capacitor from the first voltage to the second voltage.

Abstract: Disclosed are a system and method for measuring electrical characteristics of a capacitor. A measurement assembly can include a constant current assembly for selectively charging and discharging the capacitor and a counter incremented during a measurement period of a selected one of the charging and discharging. A display is used to display a value of the counter as a representation of capacitance of the capacitor.

Abstract: A process is disclosed for evaluating a measuring device comprising a capacitor (CM), with stages for charging the capacitor (CM) over an initial charging period (tk1, tk2) and for determining the capacitance charge as an initial measured value (tml). To determine a measuring condition that changes a normal state of the capacitance, e.g., moist as opposed to dry surroundings for the measuring cell, the process exhibits the following additional steps: charging the capacitance (CM) over a second charging period (tk2), which differs from the first charging period (tk1); determining the charge of the capacitance (CM) as a second measured value (tm2); and comparing the first and second measured values (tk1, tk2) to establish the comparative result.

Abstract: An electrical circuit for determining a capacitance is described. The electrical circuit includes a first device, a rectifying circuit and a feedback circuit. The first device has a first terminal and a second terminal. The first device has a first unknown capacitance and the first terminal may be configured to receive a time-varying voltage signal. The rectifying circuit has an input terminal, an output terminal and a feedback terminal. The input terminal may be coupled to the second terminal and the output terminal may be configured for coupling to an output electrical circuit. The feedback circuit may selectively couple the output terminal to the input terminal using the feedback terminal such that the output terminal and the input terminal are substantially at a common voltage.

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: The present invention is directed to a system for area efficient charge-based capacitance measurement requiring a minimum silicon area for probe pads. A structure block for the system includes several test structures coupled to a target test capacitance structure, a reference structure, and a logic block. Each test structure is coupled to a corresponding test capacitance structure. The logic block coupled to the several test structures selects a desirable test structure from the several test structures. The system may include several structure blocks and an additional logic block to select a desirable structure block. Each structure block includes a single output pin for busing each test output from the several test structures. In this manner, the silicon area may be minimized through reduction of the number of total pins and probe pads required.

Abstract: A testing circuit and method for thin film transistor display array, for testing the yield of a thin film transistor array is provided. The testing circuit includes an array tester, a test panel (DUT) and a sense amplifier array. The sense amplifier is composed of a plurality of trans-impedance amplifier units and a plurality of parasitic capacitance discharge circuit units. Every sense amplifier includes a trans-impedance amplifier, which is implemented by an operational amplifier, two switches and an operation capacitance. The trans-impedance amplifier is used to form an integrated circuit and the output is transmitted to a sampling/hold circuit via a switch. Also included is a parasitic capacitance discharge circuit that is used to form a discharge route for the charge of the parasitic capacitance.

Abstract: A capacitance change detection device includes a sensor electrode, and an electrode capacitance measurement device for measuring capacitance of the sensor electrode on the basis of a correlation value based on a reference capacitance at every first predetermined time. A detection signal is generated when a current measurement value of capacitance is changed by equal to or greater predetermined threshold value than a measurement value obtained a second predetermined time before the current measurement value is measured. The capacitance change detection device further includes a sensitivity compensation capacitance for generating capacitance variations equivalent to specific variations of capacitance of the sensor electrode, and being switched between a connected state and a disconnected state. The threshold value is determined as a difference between measurement values of capacitance of the sensor electrode measured at the connected state and at the disconnected state.

Abstract: A circuit arrangement for capacitive humidity measurement that includes a capacitive element to be measured, a plurality of switch elements, a charge storage element and a control unit electrically connected to the capacitive element, the plurality of switch elements and the charge storage element. The control unit controls the plurality of switch elements so that a number of charging operations and a number of discharging operations of the capacitive element are performed, as well as a parallel charging of the charge storage element takes place, until the charge storage element has been charged to a defined reference value, and a determination of a capacitance of the capacitive element is performed from a determination of the number of charging operations, or of a time until the reference value is reached.

Abstract: A capacitance of a capacitor member, which varies according to a dynamic force such as an acceleration force imposed on the capacitor member, is detected by a detecting circuit. The detecting circuit is composed of an operational amplifier and a switched capacitor circuit connected in parallel to each other. A reset time (t), during which a feedback capacitor in the switched capacitor circuit is discharged, is set to satisfy the following formula: t>(?C+m)/n, where ?C is an initial capacitance of the capacitor member, and n and m are constant factors having values in certain ranges. By setting the reset time (t) according to the above formula, an amount of acceleration imposed on the capacitor member is accurately detected even when the capacitor member has a certain level of the initial capacitance.

Abstract: A method and device for determining the ratio between the actual value of an RC time constant of an RC network embodied in an integrated circuit and a set value of the RC time constant includes first and second reference RC networks each having a resistor and a capacitor. The two RC networks may be oppositely connected in a circuit arrangement between first and second supply potentials, where the product of the resistance and capacitance values of the two RC networks may be equal. A normalized RC time constant may be defined for the two reference RC networks. Successive charge and discharge cycles are implemented during a predetermined evaluation period, the two capacitors being charged in a cycle during a charge time until the potential at a first node of the first reference RC network approximately corresponds to the potential at a second node of the second reference RC network. The two capacitors may be subsequently discharged for a discharge time.

Abstract: An optical submarine communication system has a land cable connected to a terminal apparatus which is installed on land near the seashore for transmitting an optical signal and electric power. The land cable is connected to an optical submarine cable through a beach manhole, and a repeater is connected to the optical submarine cable. The optical submarine communication system has a surge suppressor provided on the land cable, whereby a surge generated from the terminal apparatus side because of a lightning stroke or an insulation failure is suppressed and prevented from reaching and damaging the repeater.

Abstract: A circuit for predicting the dead time is provided. The circuit includes a plurality of integrators, a plurality of comparators, and a logic circuit. Based on a reference signal provided externally, a first charging operation is delayed by a predetermined delay time during one period of the reference signal, such that the integrators maintain at a voltage level in a next period of the reference signal. Then, the integrators further perform another charging operation during the next period, and the charging voltage is compared with the maintained voltage value. When the charging voltage exceeds the maintained voltage, a reset signal is generated by the logic circuit.

Abstract: One embodiment of the present invention provides an electronic circuit and method for measuring a capacitance. A signal generating mechanism generates a signal having a predefined frequency and predefined low and high voltage levels on one terminal of the capacitance. The other terminal of the capacitance is coupled to a switching mechanism. The switching mechanism is set to couple the other terminal of the capacitance to a first amplifier or a second amplifier for a portion of each signal cycle thereby full-wave rectifying a transient current flowing between the two terminals in the capacitance. Outputs of the first amplifier and the second amplifier are coupled to a current measurement mechanism for measuring the current. The capacitance is determined from the measured current. Several variations on this embodiment are provided.

Abstract: An electric potential fixing apparatus is provided that can prevent the combined total amount of electricity of a connection line between the first capacitance and the second capacitance from changing even when the electric potential of the connection line between the first capacitance and the second capacitance is fixed in the case where the first capacitance and the second capacitance are directly connected. This electric potential fixing apparatus has the first high resistance (3) and the second high resistance (4) and includes a voltage supply circuit (1) that preserves the combined total amount of electric charge of a measuring capacitance (14) and a fixed capacitance (15) and maintains constant the electric potential of a signal line (17) that connects the measuring capacitance (14) and the fixed capacitance (15). And an output terminal (5) of the voltage supply circuit (1) is connected to the signal line (17).

Abstract: A calibrated operator-sensing circuit having a microcontroller that commands a charge-transfer sensor to send a sensor charge signal to a capacitive sensing electrode. The sensor receives a discharge signal from the electrode and outputs a corresponding raw data signal to the microcontroller that in turn sends a signal that disables the motor of a unit of power equipment upon the absence of an operator's hand on a hand-gripping surface of the equipment. The capacitive operator-hand sensing electrode operates within a predetermined output capacitor discharge range that includes preselected binary digit values that designate hands-off and hands-on conditions on the hand-gripping surface. The capacitor discharge range is effective to distinguish between the presence of an operator's hand and foreign material on the gripping surface for avoiding a false hands-on signal.

Abstract: A capacitance detection apparatus includes a first open/close switch provided between both ends of a standard capacitor, one end of the standard capacitor being connected to a first voltage source, a second open/close switch provided between one end of a first capacitor to be measured and the other end of the standard capacitor, the other end of the first capacitor to be measured being connected to a second voltage source or free space, a third open/close switch provided between both ends of the first capacitor to be measured, a voltage measurement means for measuring voltage of the other end of the standard capacitor, a switch control means for performing a first switching control performing a first switching operation to open the first open/close switch after closing thereof, performing a second switching operation to open the second open/close switch after closing thereof, and a third switching operation to close the third open/close switch after closing thereof, wherein the second and third switching oper

Abstract: A method for determining a property of an insulating film is provided. The method may include obtaining a charge density measurement of the film, a surface voltage potential of the film relative to a bulk voltage potential of the substrate, and a rate of voltage decay of the film. The method may also include determining the property of the film using the charge density, the surface voltage potential, and the rate of voltage decay. A method for determining a thickness of an insulating film is provided. The method may include depositing a charge on the film, measuring a surface voltage potential of the film relative to a bulk voltage potential of the substrate, and measuring a rate of voltage decay of the film. The method may also include determining a thickness of the film using the rate of voltage decay and a theoretical model relating to leakage and film thickness.

Abstract: A position indicator includes a time-constant circuit having an element whose characteristic continuously varies in response to operation represented as a continuous quantity such as writing force, and capable of switching the variation range of time constant in response to the variation in characteristic of the element in at least two ways; and a discharging/charging device capable of discharging the time-constant circuit from a predetermined voltage to a voltage below a specified voltage, or charging the time-constant circuit from the predetermined voltage to a voltage exceeding the specified voltage. Using the time-constant circuit and discharging/charging device, the number of waves of AC signals at a specified frequency is counted from the discharge start time to the time when the voltage falls below the specified voltage, or from the charge start time to the time when the voltage exceeds the specified voltage, by switching the variation range of time constant.

Abstract: Certain embodiments of the present invention provide a proximity detector having a simple configuration and an imaging system including the proximity detector. In an embodiment, a proximity detector mainly comprises: a single electrode mounted on a subject-side end of a movable member; a current feeding device for feeding a constant current to an electrostatic capacitor formed between the electrode and a ground; a discharging device for releasing charge from the electrostatic capacitor at intervals of a certain cycle; a binary-coding device for binary-coding the potential at the electrode relative to a ground based on a threshold; and a smoothing device for smoothing an output signal of the binary-coding device.

Abstract: A circuit and method are given, which realizes a stable yet sensitive differential capacitance measuring device with good RF-suppression and with very acceptable noise features for use in capacitive sensor evaluation systems. By evaluating the difference of capacitor values only—with the help of a switched capacitor front-end—large spreads of transducer capacitor values are tolerable. Furthermore a mode of operation can be set up, where no essential galvanic connection between sensor input and the active read-out input at any given time is existing. The solution found exhibits a highly symmetrical construction. Using the intrinsic advantages of that solution the circuit of the invention is manufactured as an integrated circuit with standard CMOS technology at low cost.

Abstract: A method for tracking the MOS oxide thickness by the native threshold voltage of a “native” MOS transistor without channel implantation for the purpose of compensating MOS capacitance variations is achieved. The invention makes use of the fact that in MOS devices the threshold voltage is proportionally correlated to the oxide thickness of said MOS device. The threshold voltage can therefore be used to build a reference voltage Vx+Vth which accurately tracks the MOS capacitance variations in integrated circuits. Circuits are achieved to create a frequency reference and a capacitance reference using said method Additionally a method is introduced to create a capacitance reference in integrated circuits using said MOSFET capacitors.