A bidirectional sensor circuit includes a sensing impedance with first and second terminals; a first operational amplifier which non-inverting input is connected to the first terminal and its inverting input is connected to the second terminal; a second operational amplifier with the non-inverting input connected to the second terminal and its inverting input is connected to the first terminal; a first diode with the anode connected to the inverting input of the first operational amplifier and whose cathode is connected to the output of the first operational amplifier; and a second diode with the anode connected to the output of the first operational amplifier and to the cathode of the first diode. The input of the circuit consists of the terminals of the sensing impedance, and the output is at the anode of the second diode and senses a load impedance connected to the first terminal of the sensing impedance.

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.

A system for precise measurement of current takes current from a current input terminal, the system includes a controlling unit, a voltage generating unit, a voltage amplifying unit, and a processing unit. After sampling the current, the controlling unit outputs a control signal to the voltage generating unit. The voltage generating unit converts the current into different voltage signals. The voltage amplifying unit amplifies the voltage signal, and outputs the amplified signal to the processing unit. The processing unit converts the amplified voltage signal to obtain a corresponding value of current. The system accurately measures currents of different magnitudes, and improves the accuracy of current detection.

Provided are embodiments for circuit for detecting an open-wire condition for a differential input. Embodiments include a sensor, and a line replaceable unit (LRU) coupled to the sensor, wherein the LRU comprises a differential amplifier to provide a sensor output. Embodiments can also include a synchronous demodulator coupled to an output of the differential amplifier through an alternating current (AC) coupling network, wherein the synchronous demodulator is configured to receive the differential amplifier output and a reference signal at the synchronous demodulator signal input and reference input, and provide a synchronous demodulator output voltage to indicate an open-wire condition. Also provided are embodiments of a method for detecting an open-wire condition for a differential input.

An extracorporeal blood treatment apparatus is provided comprising a filtration unit connected to a blood circuit and to a dialysate circuit; a control unit is configured for calculating a sodium concentration value for the blood; the estimation of the sodium concentration includes the sub-step of calculating the sodium concentration value as an algebraic sum of a main contribution term based on the isoconductive sodium concentrate and of an offset contribution term based on a concentration of at least a substance in the dialysis fluid chosen in the group including bicarbonate, potassium, acetate, lactate, citrate, magnesium, calcium, sulphate and phosphate.

A structure is described which includes two amplifiers in parallel. A first amplifier is considered an always-on amplifier. The always on amplifier provides continual measurements of a current (Isns) across an integrated polysilicon resistor for one or more analog control loops. A second amplifier is considered a switched amplifier. The switched amplifier provides measurements of the current (Isns) for one or more digital control loops. The switched amplifier is switched by one or more switches for performing offset measurements with high accuracy.

A current sensor is for determining the level of the current of a conductor of a low-voltage circuit. In an embodiment, it includes a current transformer including a magnetic core. The magnetic core is an annular core having a core inner diameter, a middle diameter and a core outer diameter. The annular core is wound with a secondary winding, including an inner opening with an inner diameter and an outer circumference with an outer diameter. The secondary winding supplies the circuit with electrical energy. The wound annular core is configured such that the difference between the middle diameter as the minuend and the inner diameter as the subtrahend is 0.5 to 0.6 times smaller than the difference between the outer diameter as the minuend and the inner diameter as the subtrahend, to achieve an optimum for supplying energy and determining the level of the current in connection with the circuit.

A current sensor including a voltage generation circuit and a voltage integration circuit is provided. The voltage generation circuit is configured to generate a first voltage according to a current to be sensed. The voltage integration circuit is coupled to the voltage generation circuit and configured to receive the first voltage and a second voltage to generate an output voltage. The voltage integration circuit includes a first amplifier, a second amplifier and a first capacitor. The first amplifier is configured to receive the first voltage and the second voltage to generate a third voltage. The second amplifier is coupled to the first amplifier and configured to receive the third voltage to generate the output voltage. The first capacitor is coupled between an output terminal of the voltage generation circuit and an output terminal of the first amplifier and configured to reduce a voltage difference between the first voltage and the second voltage.

An amplification device including: a switch including an output that is suitable for being connected to a first or a second input; a first branch that is connected to the first input, which applies a first gain to generate a first amplified signal; a second branch that is connected to the second input, which applies a second gain to generate a second amplified signal; a controller for controlling the switching of the switch to apply the first or the second amplified signal to the output, depending on whether or not the value of a predetermined quantity of the first amplified signal falls within a predetermined range. The first gain and the second gain being non-zero real numbers of opposite sign.

A circuit for receiving the output from one of either a current transformer or a di/dt sensor includes: an input pair having a first input and a second input; a first output; a second output; a current transformer input circuit connected between the first input and the second input; and a di/dt sensor input circuit connected between the first input and the second input. The current transformer input circuit is configured to receive output from a current transformer connected to the input pair and to output a signal representative of the current sensed thereby via the first output. The di/dt sensor input circuit is configured to receive output from a di/dt sensor connected to the input pair and to output a signal representative of the current or time rate of change of the current sensed thereby via the second output.