An exemplary magnetic field measurement system includes a wearable sensor unit and a controller. The wearable sensor unit includes 1) a magnetometer comprising a photodetector and 2) a magnetic field generator configured to generate a compensation magnetic field configured to actively shield the magnetometer from ambient background magnetic fields. The controller is configured to interface with the magnetometer and the magnetic field generator and includes a differential signal measurement circuit configured to measure current output by the photodetector.

An exemplary magnetic field measurement system includes a wearable sensor unit that includes a magnetometer, a magnetic field generator configured to generate a compensation magnetic field configured to actively shield the magnetometer from ambient background magnetic fields, a twisted pair cable interface assembly electrically connected to the magnetometer, and a coaxial cable interface assembly electrically connected to the magnetic field generator.

A sensor apparatus comprises an electrically conductive chip carrier comprising a busbar, a first connection and a second connection, and a differential magnetic field sensor chip which is arranged on the chip carrier and has two sensor elements. The form of the busbar is such that a measurement current path running from the first connection to the second connection through the busbar comprises a main current path and a bypass current path, wherein the main current path and the bypass current path run parallel to one another, and a bypass current flowing through the bypass current path is less than a main current flowing through the main current path. The magnetic field sensor chip is configured to capture a magnetic field induced by the bypass current.

A semiconductor device formed on a semiconductor substrate of a P type includes: a vertical resistor circuit including a resistor of an N type, the resistor forming a current path in a direction perpendicular to a surface of the semiconductor substrate; a Hall element provided on the semiconductor substrate, the Hall element being configured to supply a voltage proportional to a magnetic flux density in the direction perpendicular to the surface of the semiconductor substrate; an amplifier configured to amplify the voltage supplied from the Hall element, and supply the amplified voltage; a current/voltage conversion circuit configured to supply, as a comparison reference voltage, a voltage containing a product of a reference current IREF flowing through the vertical resistor circuit and a resistance value RREF of the vertical resistor circuit; and a comparator configured to receive the voltage supplied from the amplifier and the comparison reference voltage.

A circuit for sensing the driving current of a motor, the circuit comprising: a driver configured to generate a driving current for each phase of a multiple-phase motor, the instantaneous sum of all the driving currents being zero; a current sensor for each phase of the multiple-phase motor, each current sensor configured to measure the driving current of that phase and comprising a plurality of current sensor elements arranged with respect to each other such that each current sensor element has the same magnitude of driving current systematic error due to magnetic fields external to the driving current to be measured; and a controller configured to, for each phase of the multiple-phase motor, generate an estimate of the driving current of that phase to be the measured driving current of that phase minus 1/n of the total of the measured driving currents for all phases, n being the number of phases of the multiple-phase motor.

In multiple magnetic sensors, for a correlation function between a magnetic field applied from a magnet and a value of the magnetic field detected by the magnetic sensor at a first temperature, the value detected by the magnetic sensor when the magnetic field applied from the magnet is 0 is set to be a first offset value. For a correlation function between a magnetic field applied from the magnet and a value of the magnetic field detected by the magnetic sensor at a second temperature, the value detected by the magnetic sensor when the magnetic field applied from the magnet is 0 is set to be a second offset value. The second temperature is higher than the first temperature. A values of applied magnetic fields detected by first and second magnetic sensors are opposite in polarity.

A rotation detection apparatus includes a magnetic field generation source, a spin valve element, and a calculator. The magnetic field generation source is rotatable while generating a magnetic field, and has a temperature coefficient of residual magnetic flux density having an absolute value of 0.1%/° C. or less. The spin valve element includes a magnetic layer configured to generate a movement of a magnetic domain wall in accordance with a change in direction of the magnetic field associated with a rotation of the magnetic field generation source. The calculator is configured to detect a change in resistance of the spin valve element caused by the movement of the magnetic domain wall and to calculate the number of rotations or a rotation angle of the magnetic field generation source.

Methods and apparatus for a current sensor having an elongate current conductor having an input and an output and a longitudinal axis. First, second, third and fourth magnetic field sensing elements are coupled in a bridge configuration and positioned in a plane parallel to a surface of the current conductor such that the second and fourth magnetic field sensing elements comprise inner elements and the first and third magnetic field sensing elements comprise outer elements. Embodiments of the sensor reduce the effects of stray fields on the sensor.

A magnetic angle sensor system includes a first magnetic sensor configured to generate a first sensor signal, a second magnetic sensor configured to generate a second sensor signal, and at least one signal processor configured to: generate an angle signal including an angular value corresponding to an orientation of a magnetic field based on the first sensor signal and the second sensor signal; generate a vector length signal comprising a plurality of vector lengths corresponding to the first sensor signal and the second sensor signal; determine a vector length variance between at least two consecutively sampled vector lengths of the plurality of vector lengths; compare the determined vector length variance to a tolerance range defined by at least one of a minimum tolerance threshold and a maximum tolerance threshold; and generate a warning signal on a condition that the determined vector length variance is outside the tolerance range.

The present disclosure generally relates to a tunnel magnetoresistive (TMR) device. The TMR device includes a high radiation reflective layer between the bottom shield of the TMR device and the magnetic seed layer. The high radiation reflective layer helps to maintain the TMR device temperature during transportation between processing chambers. Additionally, the high radiation reflective layer decreases the resistance area (RA) of the TMR device while also increasing the magnetoresistance (MR) of the TMR device.