Abstract: An output buffer includes a reference capacitor; a constant current source connected in series with the reference capacitor, for generating a reference voltage with a constant gradient by charging the reference capacitor; a first transistor having its source connected to a capacitive load, and its gate connected to the connecting point of the reference capacitor and the first constant current source to be supplied with the reference voltage; a second transistor connected between the drain of the first transistor and a voltage source; a third transistor connected between the capacitive load and the voltage source; and a fourth transistor connected to the control terminal of the second transistor and to the control terminal of the third transistor, for switching the second and third transistors from an OFF state to an ON state when the first transistor is turned on.

Abstract: An exemplary embodiment of the invention is a method of characterizing capacitances of a plurality of integrated circuit interconnects. The method includes coupling a first oscillator to a first integrated circuit interconnect and coupling a second oscillator to a second integrated circuit interconnect. The first oscillator is activated to characterize the sum of (i) coupling capacitance between the first integrated-circuit interconnect and the second integrated-circuit interconnect and (ii) ground capacitance between the first integrated-circuit interconnect and a ground. In addition, both of the first oscillator and the second oscillator are activated to characterize the ground capacitance between the first integrated-circuit interconnect and the ground.

Abstract: In a capacitive voltage divider for measuring high voltage pulses with millisecond pulse duration comprising a high voltage divider including a first cascade of at least two serially arranged condensers of which one (C1) is disposed at the high potential end and another (C2) is disposed at the low potential end of the cascade, and a measuring voltage divider connected to the other condenser (C2) and including a second cascade of at least first and second serially arranged condensers (C3, C4) arranged, respectively, at the high and low potential ends of the second cascade with the second condenser being connected with its low voltage side to a signal supply line leading to a measuring device, and an ohmic resistor (R1) arranged in parallel with the first condenser and a resistance (R2) connected to the one and first condensers in parallel with the second condenser (C4), the ohmic resistor (R1) is so dimensioned that

Abstract: A method and an apparatus for providing non-contact measurement of waveforms proximate to a surface of a sample. In one embodiment, the described apparatus includes a composite probe waveform generator configured to provide a composite probe waveform having a plurality of overlapping component probe waveforms. Each of the overlapping component probe waveforms have a repetition rate substantially equal to the repetition rate of the sample waveform to be measured from the sample. The apparatus includes a cantilever with a signal path to carry the composite probe waveform to a position above the sample surface where the sample waveform is to be measured. In one embodiment, each of the component probe waveforms of the composite probe waveform is modulated at a frequency near a mechanical resonance frequency of the cantilever.

Abstract: Apparatus for measuring the length of a transmission cable carrying primary and inverted multilevel transmission signals. A counter is arranged to count timing signals from the beginning of the measuring process while a filter extracts a high frequency signal component from the primary and inverted multilevel transmission signals. The extracted high frequency signal component is used to charge a capacitor. A comparator compares the level of charge of the capacitor to a reference level and issues a stop counting signal to the counter when charge of the capacitor equals the reference level. The count of the timing signals in the counter when counting halts is proportional to cable length.

Abstract: A method and apparatus for characterizing dimensions and parasitic capacitance between integrated-circuit interconnects are disclosed. The apparatus is a test structure including at least two substantially identical oscillators, at least two substantially identical counters, and a pulse generator. Each of the oscillators is connected to an integrated-circuit interconnect. Each of the counters is coupled to a respective oscillator. The pulse generator is utilized to inject a series of fixed-length clock pulses to each of the oscillators such that the parasitic capacitance of the integrated-circuit interconnects can be characterized by the ratio of oscillation periods of the oscillators to parasitic capacitances of the integrated-circuits.

Abstract: A fast, open-loop amplifier for an electronic measuring system is formed by a folded, differential, open-loop amplifier. This amplifier includes a differential common-source portion, a current mirror portion and a load portion. The current mirror portion is connected between the differential common-source portion and the load portion. The load portion is connected to a common voltage supply portion. The fast, open-loop amplifier can include multiple stages, where each stage includes the folded, differential, open-loop amplifier. In this case, each stage can have its own common voltage supply portion. Alternatively, a single common voltage supply portion can be shared between the stages. All the transistors of the differential common source portion and the load portion have the same type of doping, while all the transistors of the current mirror are the same type of doping, but of a type which is different than that used in the differential common source amplifier portion and the load portion.

Abstract: A process and a system for the operation of a resistive moisture sensor, in particular on the windshield of a motor vehicle, wherein the conductivity of the moisture sensor is measured shortly after a sudden change in a signal fed to the moisture sensor and measured at at least one later time. Information as to the nature and degree of the dirtying of the windshield is obtained by the measured values.

Abstract: An RF matching network provides matching between a charged first transmission line and a relay circuit which is switched to connect the charged transmission line to one end of a second transmission line to generate a high-voltage, high-current test pulse for a DUT connected to the other end of the second transmission line. A low pass filter section of the RF matching network suppresses transient and ringing signals which might pass through the parasitic capacitance of the relay circuit and which trigger the prematurely trigger the DUT. To remove residual charge after discharging the first transmission line, the transmission line is grounded with a GND relay before leakage tests are conducted to prevent electrically stress of destruction of leakage testing circuitry if the residual charge is not dissipated before testing for leakage.

Abstract: A pulse generator is provided with a photoconductor in which first to third transmission lines composed of conductive film are formed on a semi-insulating substrate and the transmission lines are separated by first and second narrow gaps, and provides short pulses from short electrical pulses generated on these transmission lines in accordance with short optical pulses irradiated upon each narrow gap. Semiconductor lasers effect the irradiation of short optical pulses upon the first and second narrow gaps. A delay is conferred upon short optical pulses irradiated upon one of the first and second narrow gaps such that pulse height of short electrical pulses generated on the first to third transmission lines is maximized.

Abstract: An apparatus for sensing two parameters of a hydraulic system having a hydraulic line includes a pair of electrodes contained within the line and oppositely spaced, forming a capacitor. The apparatus alternately produces first and second charging currents having first and second constant magnitudes, respectively, and charges the capacitor to respective first and second predetermined voltages. The apparatus detects the time needed to charge to the first and second predetermined voltages and produces a pulse width modulated signal having a series of alternating first and second pulses. The first and second pulses are indicative of the first and second parameters, respectively. The first pulse is defined by the time required to charge the capacitor to the first predetermined voltage. The second pulse is defined by the time required to charge the capacitor to the second predetermined voltage. The apparatus determines the two parameters as a function of the pulse width modulated signal.

Abstract: An apparatus for identifying components associated with the liquid in an electrically non-conductive container utilizing a pair of electrodes. The container extends along a particular dimension such that the first electrode is placed adjacent the exterior of the container and at least a second electrode is placed adjacent the exterior of the container in spaced configuration from the first electrode and along the particular dimension of the container. A generated output signal is coupled into the liquid via the first electrode. The output signal is coupled to the second electrode after passing through the liquid component. The output waveforms are analyzed to determine the electrical characteristics of the liquid in order to identify a component within the container.

Abstract: An apparatus and method for measuring the variation in the capacitance of a capacitive sensor. The apparatus and method include means for constantly applying a constant electrically current to an electrode of the capacitor and means for generating a first series of timing pulses. The voltage on the capacitor is compared to a reference voltage and an electrical signal is generated when the voltage on the capacitor reaches a first voltage which exceeds the reference voltage. The first series of timing pulses emitted by the generating means from the time that the charging of the capacitor beings until the electrical signal is generated is counted and an output signal is generated corresponding to the number of timing pulses counted. An application of the sensor to the measurement of the change in length of a telescoping device such as a shock absorber is also disclosed.

Abstract: Multiple frequency sources are used to apply a time varying signal to a scanning tunneling microscope and a current or voltage passing between the electrodes of the microscope is measured by a microwave spectrum/network analyzer which detects simultaneously at the multiple input frequencies and combinations thereof. This permits multiple substances to be monitored simultaneously. By choosing appropriate frequencies of input signals to be mixed or combined before application to the sample, it is possible to measure at a difference frequency which may improve signal to noise ratio and possible to match generating and reaction potentials and relaxation times to render detection possible. When applied to an array of Coulomb blockade devices used as a current standard, accuracy of the standard can be tested and the signal-to-noise ratio can be improved in the measurements, or the thresholds of the devices can be detected.

Abstract: A circuit and method is disclosed which determines the physical position of a selected resistance setting of a mechanical variable resistive component, such as a potentiometer, between its mechanical limits as a ratio of its selected resistance and its total resistance. The circuit includes a potentiometer, a capacitor and a microprocessor, which form a charging circuit. The microprocessor has three I/O pins, which are connected to the three terminals of the pot. The capacitor is connected in series to the pot, so that it can be charged by a voltage signal from the microprocessor either across the selected resistance of the pot's wiper or across the entire resistance of the pot. The microprocessor executes a program, which embodies the method of this invention.

Abstract: A digital sensor network scanner for use in monitoring resin flow and its re progress during a resin fabrication process in which a plurality of non-intersecting electrically conductive threads are arranged in a grid-like configuration with each sensor thread having a sensor input for a sensor data path so as to create a plurality of sensors is disclosed in which a first section of the scanner supplies time encoded pulses to the sensor input path. A second section of the sensor network scanner includes a plurality of detectors which are connected to the sensor data path as well as to a plurality of LEDs and which are also triggered by the same time encoded pulses applied to the sensor input path. When a sensor data path is in a conducting state, the applied time encoded pulses propagate down the sensor data path to the detector which, having simultaneously received a signal from both the network scanner and the sensor, illuminates the LED.

Abstract: A pulse discharge circuit for pulse testing an integrated-circuit device under test (DUT) is provided which uses three separate switching relays S1, S2, and S3, which are operated in a predetermined sequence. For charging the capacitance of a pulse-forming transmission line, the relay contact of S1 is closed while the relay contacts of relays S2, S3 are both open. For discharging the charge on the transmission line to form a test pulse, the relay contact of S1 is first opened, and the relay contact of S2 is then closed while the relay contact of S3 is open. After each test pulse is generated and applied to a DUT, the condition of the DUT is determined by a leakage current measurement. The relay contact S2 is opened to isolate the pulse generator circuit and then the relay contact S3 is closed.

Abstract: A new and improved method for measuring the value of a capacitor and for detecting small variations in the value of a capacitor around a reference value is described. In accordance with the invention, the capacitance of capacitor may be determined by applying a voltage input having a known amplitude and wave form V to an RC circuit having a substantially known or constant load impedance R and sampling the voltage across the resistor or capacitor at a precisely controlled elapsed time interval T. The method now permits improved detector circuits to be created for measuring small variations in value with precision and accuracy. Solid state keypads incorporating sensor cells and software algorithms provide superior human to machine interface systems which are not subject to environmentally induced errors or errors due to component aging.

Abstract: A probe apparatus includes a probe contact connected to a storage capacitance via a photoconductive switch. The photoconductive switch can be operated at high speed by means of a pulsed laser. The laser pulses (L) are synchronized with a moment in the operation cycle of the circuit at which moment the voltage at the point under test is to be measured. After a number of pulses and operation cycles the storage capacitance is charged to the voltage value (V) to be measured. Then, the capacitance does not form a load on the point under test and the voltage (V) can be determined accurately.

Abstract: A potentiometry apparatus for measuring a periodic electrical waveform existing proximate the surface of a sample such as a semiconductor wafer is disclosed herein. The potentiometry apparatus includes a pulse generator for generating a sequence of electrical pulses at a pulse frequency offset from the frequency of the surface waveform by a mixing frequency. A cantilever coupled to the pulse generator serves to carry the electrical pulses to a position proximate the surface of the sample. In a capacitive displacement mode the cantilever is mechanically displaced so as to generate a time-expanded representation of the electrical surface waveform having a repetition frequency equal to the mixing frequency. During displacement mode operation an optical detection circuit may be employed to monitor deflection of the cantilever. In a tunneling current mode the cantilever is again employed to carry the electrical pulses to a position proximate the surface of the sample.

Abstract: A circuit for responding to the output of a capacitive fuel sensor that can distinguish gasoline from methanol and produces an output that is related to the methanol proportion. The response is independent of the conductivity in the sensor resulting from fuel contamination. A square wave is employed to excite the sensor and the circuit provides for stabilizing the square wave amplitude. The circuit includes an amplitude modulation detector that converts the square wave transients into a fuel composition related voltage output that can be applied to an engine control mechanism that will adjust the automotive engine to operate efficiently with the fuel being supplied. Circuits are shown for linearizing the fuel composition to voltage response and a charge dispenser amplitude modulation detector is described wherein the detection occurs only during the square wave transient interval.

Abstract: A humidity meter includes a humidity-frequency converter (2) which is essentially a pulse oscillator, the oscillation frequency of which depends upon the impedance of a humidity sensor (1), a differentiation circuit (3) and a wave-form shaping circuit (4) which essentially operate as a pulse width modulator for adjusting pulse width of an output pulse of the converter (2) for assuring a linear relationship between humidity and the output signal, and an integrator (6) for integrating the output of the pulse width modulator to provide an output signal as a DC level. A feedback path (5) is provided to apply the output signal to the pulse width modulator for assuring a linear output irrespective of the exponential characteristics of the humidity sensor. Said differentiation circuit (3) has a capacitor (31), a first variable impedance element (32) which is controlled by said feedback path , and a second variable impedance element (33) coupled in series with the first variable impedance element (32).

Abstract: A capacitance measuring circuit uses only a DC voltage source to perform the capacitance measurement. For this purpose, the circuit is arranged to charge an unknown capacitor which is being measured from a DC source and to discharge the capacitor through a constant current circuit such that the discharge voltage across the capacitor decreases linearly from its initial value to a predetermined, final value. The measurement circuit monitors the time taken by the capacitor to discharge in order to determine the capacitance value.

Abstract: A circuit for measuring a parameter value by measuring the time required to charge a capacitor in a sensor RC circuit from a first to a second voltage includes a reference RC circuit whose capacitor is also charged between two voltage levels. The circuit is calibrated so that the time interval required to charge the reference capacitor may be used to improve the accuracy with which the parameter value is measured.

Abstract: A liquid mixing ratio detecting apparatus is designed so that an oscillation voltage generated by an oscillation unit is applied to one of a differentiating circuit and an integrating circuit, which is constituted by a combination of a capacitor composed of a pair of opposite electrodes for detecting a mixing ratio of a mixed liquid and a resistor, and a mixing ratio detecting unit produces a signal relating to an inclination rate of one of a differential waveform signal and an integration waveform signal, which is generated by one of the differentiating circuit and the integrating circuit, respectively, thereby obtaining a signal representing the mixing ratio of the mixed liquid on the basis of the produced signal relating to the inclination rate of the waveform signal.

Abstract: In an apparatus for determining the moisture content of a material by measuring the dielectric constant of the material by means of a measuring conductor which is disposed such that the material becomes a dielectric for the measuring conductor and wherein the time lapse between the application of an electrical signal to the measuring conductor and the return of the echo of the signal is employed as an indication of the dielectric constant and consequently the moisture content of the material, the electrical signal is a pulsed signal with a pulse duration which is greater than the time lapse between signal start and return of the echo of the signal start and an independent oscillator is provided whose cycles are counted during the opening state of a gate circuit which is open between the application of electrical signal to the measuring conductor and the return of the echo thereof, the counted cycles thereby providing an indication for the time lapsed from signal start to echo return in a simple manner with si

Abstract: A method and apparatus of determining the amount of impurities in an object with isothermal capacitance transient spectroscopy (ICTS) includes maintaining the object at a constant temperature while applying a predetermined voltage pulse to the object at predetermined test locations. The capacitance is measured over a predetermined time period, and the measured capacitance is processed to determine the amount of impurities in accordance with a differential coefficient obtained by differentiating the following equation used as the ICTS spectrum: ##EQU1## wherein C is the capacitance and t is the time period.

Abstract: In an evaluation circuit for a capacitive sensor, the capacitive sensor and a capacitor form a capacitive voltage divider, the end terminals of which can be fed with opposite-phase alternating voltages of the same frequency. The junction point between the capacitor and the capacitive sensor is connected, together with a tap of a voltage source of high internal resistance, to the input of an impedeance transformer. The output of the impedance transformer is connected to a synchronous demodulator to which at least one phase of the alternating voltage is fed.

Abstract: An electronic level indicator, having a housing including at least one planar surface, at least one gravity responsive sensor mounted on the housing, the sensor constituting at least a part of two branches of an electronic bridge circuit, a pulse generator coupled to the bridge circuit for feeding the bridge circuit with short pulses, a differential amplifier connected to the output of the bridge circuit, an A/D converter connected in circuit for receiving signals from the amplifier and a display unit connected to the output of the converter for displaying numerical data indicative of the inclination of the planar surface.

Abstract: Apparatus and method for detecting the presence and surface location of or the absence of an electrically conductive solar coating on a pane of glass. A capacitor is formed by placing a probe against one surface of the glass. The value of the capacitor is determined by the presence or absence of a conductive coating on the glass and by the location of any coating relative to the probe. Variations in the value of the capacitor are detected to selectively illuminate lights which indicate either the absence of a surface coating, the presence of a surface coating on a near surface or pane of the glass or the presence of a surface coating on a far surface or pane of the glass.

Abstract: A method and a device for automatic verification of genuineness of a banknote or a document comprising a watermark is described. A two-part, doubly active capacitive sensor device (4, 6, 7) is used. A symmetry property of the sensor output signal is changed in a predetermined manner when a correct watermark is present in a coinciding position with shape-adapted capacitor electrodes (4, 6).

Abstract: A digital isolation monitor comprises a digital processing signal processor P1 designed to synthesize a sine wave in real time by a table, and to send the digital values of this sine wave to a digital-to-analog converter of an input channel to generate a low-frequency AC reference signal with a very low, stable phase distortion factor. An acquisition channel is fitted with a switching unit operating in conjunction with a dual measurement circuit to send an injected voltage signal and a leakage current signal to a low-pass analog filter in series with a sample-and-hold circuit and an analog-to-digital converter. The processor P1 then performs synchronous demodulation and transmits the data to a microcontroller P2.

Abstract: A transducer system and method of use thereof by sequentially operating a comparator to produce a series of pulses in which the time distribution of the pulses is representative of the transducer value, and is used to normalize the sensed value in the event that the total transducer value varies due to environmental influences. The transducer is adapted to monitor the substantially linear movement of the level (fuel-air interface) of fuel in a tank and the angular positon of an input shaft.

Abstract: A transducer system and method of use thereof by sequentially operating a comparator to produce a series of pulses in which the time distribution of the pulses is representative of the transducer value, and is used to normalize the sensed value in the event that the total transducer value varies due to environmental influences. The transducer is adapted to monitor the substantially linear movement of the level (fuel-air interface) of fuel in a tank and the angular position of an input shaft.

Abstract: An electronic level indicator, having a housing including at least one planar surface, a gravity responsive sensor mounted on the housing, the sensor constituting at least a part of two branches of an electronic bridge circuit, a pulse generator coupled to the bridge circuit for feeding the bridge circuit with short pulses, a differential amplifier connected to the output of the bridge circuit, an A/D converter connected in circuit for receiving signals from the amplifier and a display unit connected to the output of the converter for displaying numerical data indicative of the inclination of the planar surface.

Abstract: An impedance meter with improved measurement accuracy obtained by controlling the level of the signal source. The impedance meter comprises a signal source, feedback amplifier, synchronous detector, A/D and control logic. The source level is maintaind by the control logic at a predetermined value by measuring the output of a synchronous detector and intermittently adjusting the level of the source thereby compensating for variations in test object's impedance. Control logic algorithms employed include successive substitution, bisection and linear interpolation.