Estimating components of a grid impedance, Z, of a power grid being coupled to a power generating unit at a point of interconnection is disclosed. A voltage, Vmeas, across the point of interconnection; an active current, IP, and/or an active power, P, delivered by the power generating unit to the power grid; and a reactive current, IQ, and/or a reactive power, Q, delivered by the power generating unit are determined. A parameter estimation vector is estimated using a recursive adaptive filter algorithm, and on the basis of Vmeas, IP, P, IQ and/or Q. A model representation of the power grid is created on the basis of the parameter estimation vector, and a system DC gain vector for the power grid is calculated, using the model representation. Finally, Z, and/or a resistance, R, of Z, and/or a reactance, X, of Z, is derived from the system DC gain vector.

Estimating components of a grid impedance, Z, of a power grid being coupled to a power generating unit at a point of interconnection is disclosed. A voltage, Vmeas, across the point of interconnection; an active current, IP, and/or an active power, P, delivered by the power generating unit to the power grid; and a reactive current, IQ, and/or a reactive power, Q, delivered by the power generating unit are determined. A parameter estimation vector is estimated using a recursive adaptive filter algorithm, and on the basis of Vmeas, IP, P, IQ and/or Q. A model representation of the power grid is created on the basis of the parameter estimation vector, and a system DC gain vector for the power grid is calculated, using the model representation. Finally, Z, and/or a resistance, R, of Z, and/or a reactance, X, of Z, is derived from the system DC gain vector.

A method and apparatus for calibrating an impedance measurement device are provided. The impedance measurement device outputs a first AC signal to a phase-locked current generator. The phase-locked current generator generates a second AC signal having a phase that is locked to a phase of the first AC signal and having an amplitude that is representative of a presented impedance having a known impedance value. The phase-locked current generator outputs the second AC signal to the impedance measurement device. The impedance measurement device performs an impedance measurement based on the second AC signal to produce a measured impedance value associated with the presented impedance. The impedance measurement device is calibrated based on the measured impedance value and the known impedance value of the presented impedance.

A method and apparatus for calibrating an impedance measurement device are provided. The impedance measurement device outputs a first AC signal to a phase-locked current generator. The phase-locked current generator generates a second AC signal having a phase that is locked to a phase of the first AC signal and having an amplitude that is representative of a presented impedance having a known impedance value. The phase-locked current generator outputs the second AC signal to the impedance measurement device. The impedance measurement device performs an impedance measurement based on the second AC signal to produce a measured impedance value associated with the presented impedance. The impedance measurement device is calibrated based on the measured impedance value and the known impedance value of the presented impedance.

A semiconductor test device for measuring a contact resistance includes: first fin structures, upper portions of the first fin structures protruding from an isolation insulating layer; epitaxial layers formed on the upper portions of the first fin structures, respectively; first conductive layers formed on the epitaxial layers, respectively; a first contact layer disposed on the first conductive layers at a first point; a second contact layer disposed on the first conductive layers at a second point apart from the first point; a first pad coupled to the first contact layer via a first wiring; and a second pad coupled to the second contact layer via a second wiring. The semiconductor test device is configured to measure the contact resistance between the first contact layer and the first fin structures by applying a current between the first pad and the second pad.

A semiconductor test device for measuring a contact resistance includes: first fin structures, upper portions of the first fin structures protruding from an isolation insulating layer; epitaxial layers formed on the upper portions of the first fin structures, respectively; first conductive layers formed on the epitaxial layers, respectively; a first contact layer disposed on the first conductive layers at a first point; a second contact layer disposed on the first conductive layers at a second point apart from the first point; a first pad coupled to the first contact layer via a first wiring; and a second pad coupled to the second contact layer via a second wiring. The semiconductor test device is configured to measure the contact resistance between the first contact layer and the first fin structures by applying a current between the first pad and the second pad.

The present disclosure relates to an efficient wireless power charging apparatus and a method thereof. The wireless power charging apparatus includes: a plurality of transmitters each including a transmission resonance unit configured to transmit power using power provided from a power unit and including one capacitor and one inductor; a receiver including a reception resonance unit configured to receive power transmitted from the plurality of transmission resonance units and including one capacitor and one inductor, and a load performing charging using received power; and a control unit configured to determine mutual inductance between each of the transmission resonance units and each of the reception units and equivalent load impedance of the receiver, configured to determine any one of the plurality of transmitters as a reference transmitter and determine a current ratio between the reference transmitter and another transmitter, and configured to determine an output current of each of the plurality of transmitters using each of the mutual inductances, the equivalent load impedance of the receiver, and the current ratio between the reference transmitter and another transmitter.

The present disclosure relates to an efficient wireless power charging apparatus and a method thereof. The wireless power charging apparatus includes: a plurality of transmitters each including a transmission resonance unit configured to transmit power using power provided from a power unit and including one capacitor and one inductor; a receiver including a reception resonance unit configured to receive power transmitted from the plurality of transmission resonance units and including one capacitor and one inductor, and a load performing charging using received power; and a control unit configured to determine mutual inductance between each of the transmission resonance units and each of the reception units and equivalent load impedance of the receiver, configured to determine any one of the plurality of transmitters as a reference transmitter and determine a current ratio between the reference transmitter and another transmitter, and configured to determine an output current of each of the plurality of transmitters using each of the mutual inductances, the equivalent load impedance of the receiver, and the current ratio between the reference transmitter and another transmitter.

To measure the resistance area product of a high resistivity layer using a microscopic multi point probe, the high resistivity layer is sandwiched between two conducting layers. A plurality of electrode configurations/positions is used to perform three voltage or resistance measurements. An equivalent electric circuit model/three layer model is used to determine the resistance area product as a function of the three measurements.

Accurately measuring bio-impedance is important for sensing properties of the body. Unfortunately, contact impedances can significantly degrade the accuracy of bio-impedance measurements. To address this issue, a method is provided for estimating an impedance matrix of parasitic network disposed between a first network and a second network of a bio-impedance measurement system, the method comprising determining an impedance matrix for the first network (Z.sub.MUX) based on an impedance matrix for the second network (Z.sub.LOAD) for at least one known load condition; fitting Z.sub.MUX values for Z.sub.LOAD for the at least one known load condition to estimate parameters of the impedance matrix of the intervening network.