Abstract: A method of deriving an equivalent circuit model for a passive component includes a first step of providing a given frequency characteristic of a capacitor, a second step of forming one of an RC circuit, an RL circuit, and an RCL circuit using frequency-independent resistances (R), capacitances (C) and/or inductances (L), as the equivalent circuit model representing a circuit capable of performing a simulation in a time domain, a third step of composing an evaluation function for evaluating accuracy of the equivalent circuit model formed in the second step, and a fourth step of determining values of the circuit components by minimizing the evaluation function composed in the third step. The method with a simulator adapted for implementing this method and a computer-readable storage medium containing a recorded program, derives the equivalent circuit model for a capacitor. The model is capable of performing a simulation in the time domain using a common procedure not dependent upon types of passive components.

Abstract: A moisture meter (1) has a capacitive sensing circuit (11-16) feeding into a digital control circuit having a microcontroller (17). Input buttons (20, 22, 23) allow a user to select a material being surveyed. They also allow the user to instruct the meter (1) to hold a particular reading. This allows it to be more conveniently read. The output of the digital control circuit is fed via an ADC (18) to a moving coil meter (4). This provides an easy-to-read display in which trends as the meter (1) is moved across a surface are easy to track.

Abstract: A method of uniquely extracting both intrinsic and parasitic components from a single set of measured S-parameters is useful for extracting a single set of measured S-parameters for the development of non-linear Field Effect Transistor (FET) models. Competitive extraction where multiple trial solutions are attempted spanning a region or space of feedback impedances is used. Extraction is followed by optimization that reduces the extracted values to a model that better fits measured S-parameters. Optimization can be achieved by further evaluating the speed of convergence in an error metric.

Abstract: The invention presents a new methodology to monitor and display the resin flow during fabrication of organic matrix composite laminates in real-time or near real-time and includes data acquisition, remote data distribution, flow analysis and reconstruction, and flow visualization. The data acquisition apparatus is based on SMARTweave technology, as described in U.S. Pat. No. 5,210,499, which provides the location of points on the flow front as a function of time by using voltage measurements. However, the methodology will monitor and display the resin flow if the location and time information is acquired using modified SMARTweave or different apparatus.

Abstract: An on-board micro-electromechanical (MEMS) isolator is provided on board a power semiconductor device for measuring voltage, current, or both. In particular, the power semiconductor may comprise a plurality of transistors connected in parallel, such that a MEMS isolator connected in parallel with one of the transistors measures voltage across the semiconductor. A MEMS isolator may further be connected in series with the transistors to measure current flow thereacross. A compensation circuitry may be provided to receive the current output from the isolator, and determine total current flow through the power semiconductor.

Abstract: A radio-frequency reception arrangement for a magnetic resonance apparatus has a number of independent antennas and pre-amplifiers. The number of pre-amplifiers is less than the number of independent antennas. A switching matrix is arranged between the pre-amplifiers and the antennas for selective, signal-dependent connection of the pre-amplifiers to the antennas.

Abstract: A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

Abstract: Method and device for the rapid detection of short-circuits in an electrical network. The method is based on estimating the electrical characteristics of the short-circuit load and calculating the peak value of the current on the basis of N successive samplings of the instantaneous current (i(t)). If the calculated value, typically available before the current actually attains this value, is greater than a pre-established threshold (Icc), a signal (C) is emitted indicative of a short-circuit fault. The calculation of the peak value may occur automatically for example upon switching on, or be subject to the exceeding of a guard threshold (Is) by the instantaneous current (i(t)). Moreover, the method makes it possible concurrently to determine the value of the power factor of the short-circuit (cos &phgr;) and the phase of the voltage at the moment of the short-circuit.

Abstract: An impedance detection circuit includes a circuit input having a first contact and a second contact, a reference voltage rail coupled to the first contact, and a memory cell having a data node coupled to the second contact and an output. When the memory cell is read, the logic state of the output provides an indication of an impedance coupling the first and second contacts at the circuit input. The impedance detection circuit can be utilized to sense resistive and capacitive inputs and has any number of applications, including use as a digital hygrometer and as a fingerprint sensor.

Abstract: In an arrangement that can be implemented with a simple circuit, the load is connected in parallel to an additional resistor. The primary-side input resistance of the transformer is measured, and when the input resistance differs from a predefined value, a load malfunction is signaled.

Abstract: A device and method are provided for determining the thickness of a layer of solid ice, a mixture of ice and water, or a mixture of ice and other liquid, accumulated on the outer surface of an object. First and second total impedance sensors are operated at first and second frequencies. Corresponding first and second AC total impedance measuring circuits are coupled to the first and second sensors to produce output voltages based on the total impedance changes sensed by the sensors. A processor is coupled to the first and second measuring circuits to generate an output value using the measured output voltages. The output value is indicative of the thickness of the ice or ice and water mixture, or ice and other liquid.

Abstract: An impedance meter includes a floating type ammeter which measures a voltage across a current detection resistor and determines a current flowing therethrough. A balun eliminates the common mode voltage component in the high frequency range; and a differential amplifier eliminates the common mode voltage component in the low frequency range. The common mode rejection (common mode elimination) effect of the balun and differential amplifier crosses over at a crossover frequency where the impedance of an capacitor and the impedance of the balun are equal. As a result, the impedance meter is capable of measuring a broad range of impedances across a wide range of frequencies, both the low frequency and high frequency range.

Abstract: In the method of calculating the impedance of an electromagnetic part, the cost is low, the calculation time is short, and data for analysis are easy to handle.

Abstract: The device has a single strip having a first end, a second end, a length and a width. The first end of the strip is curved toward the second end of the strip to form a loop having a height. The length is approximately 10 mm, the width is approximately 5-8 mm, and the height is approximately 0.8-1.2 mm. The loop is preferably fabricated from copper. The loop is mounted directly to a test instrument such as a computer controlled impedance analyzer or network analyzer. The test instrument measures the inductance and resistance of the loop with no thin film sample placed therein, and then measures the inductance and resistance of the loop containing the sample under test. From these measurements, the device ultimately derives the permeability of the sample under test.

Abstract: An impedance probe circuit and method presents a balanced load to a DC or RF voltage source and to two voltage measurement nodes. The impedance probe circuit is accurate for measurement of an impedance device X which has a range always less than the value of a characteristic impedance C. A source terminal is coupled to a voltage source having a series impedance C. A test resistor T is connected between the source terminal and one terminal X1 the unknown impedance. A reference resistor R is connected between the source terminal and the other terminal X2 of the unknown impedance. The parallel combination of the test resistor T and the reference resistor R has an impedance substantially equal to C/3. A third impedance of value C/3 is connected to the node X1 and to a first voltage measurement terminal. A fourth impedance of value C/3 is connected to the node X2 and to a second voltage measurement terminal.

Abstract: A measuring circuit obtains desired characteristic values of a device under test by accurately measuring a voltage and a current. Errors are eliminated that originate from the transmission characteristics of cables used in measurements at high frequencies and measurements using long cables. The errors are eliminated by connecting resistors that are equal in resistance to the characteristic impedance of cables, to the inputs of the cables which connect the device under test to a measuring device.

Abstract: An impedance meter is not adversely affected by errors originating from changes in characteristics of measurement cables under measurement conditions such as in an environmental test wherein an element to be measured is remote and high and wide measurement frequencies are used. The voltage and the current of an element to be measured are measured to obtain its impedance and the like. A circuit configuration is provided wherein a cable for supplying a measurement signal to the element to be measured and for detecting the current flowing through the element to be measured is a triaxial cable and a cable for detecting the voltage is a coaxial cable, and wherein impedance matching is performed at the ends of the triaxial cable and the coaxial cable on the side of a measuring device and a balun is provided to float an ammeter on a coaxial cable connecting the ammeter-side end of the triaxial cable to the ammeter.

Abstract: A system for measuring a broad range of impedance values with high precision and over a broad frequency band. Both the broadrange impedance measurement capability of the V-I method and the broadband frequency measuring capability of the reflection coefficient method are provided. A remote measurement capability is also available. Based upon the V-I method, a selection is made between a circuit to achieve an ideal open and a circuit to achieve an ideal short circuit in response to the impedance values. A boundary for selecting the impedance is, for instance, 50.OMEGA.. To measure a high impedance, the ideal open type circuit is selected; to measure a low impedance, the ideal short circuit is selected. The source and measuring instruments are extended by a coaxial cable. A floating measuring instrument is obtained by using a balun. Impedance measurements for 1 MHz to 2 GHz are possible.

Abstract: An acoustic microscope assembly for atomic level inspection of a target object includes a cantilever arm with a sharp tip on its lower surface and a zinc oxide piezoelectric thin film on its upper surface. High frequency excitation signals, having a frequency of at least 50 Megahertz, are applied to the piezoelectric thin film so as to generate high frequency acoustic signals that are transmitted through the sharp tip so as to impact on a target object. The assembly can either receive acoustic signals reflected by the target object, or it can receive acoustic signals that have propagated through the target object. One method of using this assembly is to apply a continuous wave signal to the piezoelectric thin film while scanning the target object, and measuring characteristics of the target object at various positions thereof by measuring the resonant frequency of the transmitted high frequency acoustic signals.

Abstract: An apparatus is adapted to detect the linear extension of a hydraulic cylinder. The hydraulic cylinder defines a variable length coaxial resonant cavity. Under the control of a controller, a transmitting section and a receiving section are used to determine the linear extension of the hydraulic cylinder. The controller detects two subsequent harmonics of the resonant frequency and responsively determines the resonant frequency. The linear extension is determined as a function of the resonant frequency.

Abstract: A method for the nondestructive measurement of the moisture content of single grain kernels, seeds, nuts, or fruits which is independent of their weight, thickness, and projected area. At least two independent parameters of complex electrical impedance or admittance of a single grain kernel, seed, nut, or fruit are measured at two different frequencies and the moisture content is calculated therefrom.

Abstract: A circuit element measuring apparatus for measuring a parameter of a device under test (DUT) includes a signal source, a voltmeter, a zero detection amplifier, and a compensation network all of which are coupled to the DUT by four shielded lines. The compensation network is also coupled to a range resistance. The compensation network provides two independent sets of correction data. One is based on the length of the shielded line and the other is based on the range resistance used. The parameter being measured can then be adjusted by the appropriate set of correction data to provide a more accurate measurement. A method of operating the circuit element measuring apparatus for measuring the parameter of the DUT by generating the two sets of correction data and adjusting the parameter accordingly.

Abstract: An apparatus and method for accurately monitoring the flow and cure rate of a resin material. The method is accomplished through the use and incorporation of efficient sensors as integral components of a composite resin structure material. The sensors used are electrically conductive threads arranged in a non-intersecting, grid-like configuration. They may be placed into or between composite resin materials. These sensors serve as leads which are connected to a computer through a multiplexer/rapid switching system and a scanner. The data obtained for the monitoring of the flow and cure of resin is stored on a computer system and is presented on the computers' graphic window.

Abstract: An apparatus is adapted to detect the linear extensions of a plurality of hydraulic cylinders. Each hydraulic cylinder defines a variable length coaxial resonant cavity. Under the control of a controller, a transmitting section, a receiving section and multiplexers are used to multiplex RF signals to and from the cavity of each cylinder and to determine the resonant frequency of the cavity. The controller determines the linear extension of each cylinder as a function of its resonant frequency.

Abstract: A monolithic coupled-dual resonator crystal filter coupled to improve switching arrangements is tested using both resonator ports to quickly measure selected resonator parameters useful in frequency adjustment, production and test systems as well as accurately measuring other filter crystal parameters, all without requiring removal of the crystal structure from the test fixture.

Abstract: In an impedance and transfer characteristic measuring apparatus sine-wave and cosine-wave data are produced using data obtained by accumulating a fixed phase value in synchronism with a clock signal and the sine-wave data is provided to a device under test after D-A conversion. Multiplied outputs are obtained by multiplying type D-A converting part which D-A converts the sine-wave data and the cosine-wave data, using two signals related to an item of measurement of the device under test as analog multiply inputs therefor. An intergration control signal of a predetermined level is generated by a signal generating part for the half-cycle period of a sine-wave test signal in synchronism with a measurement start signal. For the period during which the intergration control signal is yielded the multiplied outputs are respectively integrated in an integration circuit part to thereby obtain vector-detected outputs.

Abstract: An apparatus for and a method of measuring capacitance employs a charge measuring system. While a capacitive element, which may be an unknown capacitor, is charged completely to a predetermined voltage, a charge proportional to the capacitance of the capacitive element is accumulated on the feedback capacitor of an integrating operational amplifier. Thereafter, the charge is measured by measuring the time required to completely remove the charge from the feedback capacitor using the same predetermined voltage as a reference. In a preferred embodiment, the present invention is manifested as a capacitance measurement feature in a hand-held multimeter wherein a largely conventional dual-slope analog-to-digital converter is employed as the charge measuring system.

Abstract: In coupled-dual resonator crystals, key parameters, such as resonator frequencies and synchronous peak separation frequency, are determined using a four frequency measuring process and apparatus wherein additional impedance is connected in parallel with the driving point impedance of the input resonator so as to allow the measurement of the critical frequencies above about 45 MHz.

Abstract: A third case or manner of obtaining the four critical frequencies useful in accurately measuring coupled-dual resonator crystals, wherein both ports of the crystal structure are monitored, rather than a single port in the previously known cases. Here the B port, for example, is monitored with the A-side open-circuited or with a capacitor in parallel with it, and the A port is monitored with the B-side short-circuited.

Abstract: In a switchable impedance tester for measuring very small impedances, the effect of switch impedances is eliminated by connecting the test load between two switching transistors in their emitter-collector circuit, and driving them with operational amplifiers arranged to urge their inputs into equality. A test voltage source is connected across first inputs of the amplifiers, and the other inputs are connected between the respective transistors and the load. This produces an operational condition in which the voltage across the load is independent of the parameters of the switching transistors, i.e. the switching transistors appear to have zero impedance.

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.

Abstract: For measuring the inductance of a workpiece, a device which includes an inductance meter, respective D.C. and A.C. power sources as well as a guard line circuit. In order to simulate conditions of actual use of the workpiece, the D.C. power source is connected to provide a direct current bias through the workpiece. A measuring current produced by the A.C. power source and applied to the workpiece is detected via the inductance meter. The guard line circuit is coupled so as to prevent any portions of the A.C. measuring signal from undesirably flowing through the D.C. power source.

Abstract: An active, artificial inductor circuit is utilized as a two-terminal pair circuit used to provide an apparatus capable of measuring the AC electrical parameters of a device such as a resistor, a capacitor or an inductor at a desired frequency with less error in measurememt at lower frequencies.

Abstract: A method and apparatus for determining the impedance of the discharge in a plasma reactor system comprising a tuning box having variable capacitors is described. The impedance of the discharge is determined in dependence on a pre-established relationship between the operational positions of the variable capacitors on the one hand and the impedance of the discharge on the other. The ionic current relative to the discharge in the reactor also may be determined by taking into account the high frequency voltage of the reactor.

Abstract: Apparatus and method for determining capacitive and resistive values of an electrical component, such as a fuel level determining probe, includes a waveform generator for subjecting the probe to a time-varying waveform that includes a linearly varying ramp portion and a fixed, constant portion. A selectively controlled sample and hold circuit senses the voltage potential of the probe in response to a zero-crossing detector during the linearly varying ramp portion of the waveform to provide information indicative of the capacitive value and again senses the voltage potential at selected time thereafter during the fixed portion of the waveform to provide resistive value information. The output of the sample and hold is provided to an analog-to-digital converter which provided digital information to a stored-program controlled processor which provides the desired output information.