Abstract: A differential amplifier circuit includes a basic differential amplifier circuit including an operational amplifier configured to amplify a potential difference between output ends of a first input resistor and a second input resistor, a feedback resistor connected to the output end of the first input resistor, and a first resistance element connected to the output end of the second input resistor. Furthermore, the differential amplifier circuit includes a high-precision operational amplifier having an offset voltage or a drift voltage lower than that of the operational amplifier. The high-precision operational amplifier includes an inverting input terminal connected to the output end of the first input resistor and an output terminal connected to the output end of the second input resistor.

Abstract: A current measurement component including a bridging portion bridging a pair of side surface portions, a pair of coaxial components attached to the pair of side surface portions, respectively, each coaxial pair including an inner conductor that extends through a hole formed in a corresponding side surface portion of the pair of side surface portions, a connection portion electrically connecting the inner conductors of the pair of coaxial components, and a tube-like portion enclosing the connection portion with a gap formed between the tube-like portion and an outer peripheral portion of the connection portion. The pair of side surface portions and the bridging portion are electrically conductive and electrically connected, and the tube-like portion includes a base end portion electrically connected to a first side surface portion of the pair of side surface portions and a distal end portion electrically separated from the outer conductor of coaxial component pairs.

Abstract: A current sensor for detecting a magnitude of a current flowing through a measuring object has a magnetic core having a first magnetic core and a second magnetic core that is arranged magnetically in parallel to the first magnetic core, wherein the first magnetic core has a magnetic permeability that is higher than that of the second magnetic core in a first frequency band, and the first magnetic core has a magnetic permeability that is lower than that of the second magnetic core in a second frequency band, the second frequency band being higher than the first frequency band, and the current sensor detects the magnitude of the current in a frequency band that is constituted by combining the first frequency band and the second frequency band.

Abstract: A current sensor includes an excitation detection winding configured such that an excitation signal for exciting a second magnetic core is input, the excitation detection winding detects magnetic flux flowing through the second magnetic core and outputs a detection signal indicating a measurement-target current. The current sensor includes an auxiliary winding that detects the magnetic flux and outputs an auxiliary signal indicating the measurement-target current. The current sensor includes a feedback winding wound around first and second magnetic cores, the feedback winding being configured such that a signal generated from the detection signal is input, and the feedback winding being wound to cancel out magnetic flux of the first and second magnetic cores. The current sensor includes a circuit to output an output signal indicating a level of the measurement-target current by modifying a signal output from the feedback winding based on a correction signal generated from the auxiliary signal.

Abstract: A current sensor for detecting a magnitude of a current flowing through a measuring object has a magnetic core having a first magnetic core and a second magnetic core that is arranged magnetically in parallel to the first magnetic core, wherein the first magnetic core has a magnetic permeability that is higher than that of the second magnetic core in a first frequency band, and the first magnetic core has a magnetic permeability that is lower than that of the second magnetic core in a second frequency band, the second frequency band being higher than the first frequency band, and the current sensor detects the magnitude of the current in a frequency band that is constituted by combining the first frequency band and the second frequency band.

Abstract: A current detector includes: a current sensor that is constructed using a Rogowski coil, detects a current flowing in a measured object, and outputs a detection signal corresponding to a current value of the current; a transfer line that is constructed of a distributed constant line and transfers the detection signal; an impedance converting circuit that is provided between the current sensor and the transfer line and has an input impedance equal or substantially equal to a characteristic impedance of the current sensor; an integrator circuit that integrates the detection signal inputted via the transfer line and outputs an output signal indicating a current value of the current; and a resistance circuit that has a resistance value that is equal or substantially equal to a characteristic impedance of the transfer line and is connected in series between the transfer line and the integrator circuit.

Abstract: A current detector includes: a current sensor that is constructed using a Rogowski coil, detects a current flowing in a measured object, and outputs a detection signal corresponding to a current value of the current; a transfer line that is constructed of a distributed constant line and transfers the detection signal; an impedance converting circuit that is provided between the current sensor and the transfer line and has an input impedance equal or substantially equal to a characteristic impedance of the current sensor; an integrator circuit that integrates the detection signal inputted via the transfer line and outputs an output signal indicating a current value of the current; and a resistance circuit that has a resistance value that is equal or substantially equal to a characteristic impedance of the transfer line and is connected in series between the transfer line and the integrator circuit.