A magnitude and direction of at least one of a reset current and a second stabilization current (that produces a reset field and a second stabilization field, respectively) is determined that, when applied to an array of magnetic sense elements, minimizes the total required stabilization field and reset field during the operation of the magnetic sensor and the measurement of the external field. Therefore, the low field sensor operates optimally (with the highest sensitivity and the lowest power consumption) around the fixed external field operating point. The fixed external field is created by other components in the sensor device housing (such as speaker magnets) which have a high but static field with respect to the low (earth's) magnetic field that describes orientation information.

A magnetic field detection device includes a magnetism detection element, a modulator, and a demodulator. The magnetism detection element has a sensitivity axis along a first direction. The modulator is configured to impart a spin torque to the magnetism detection element. The spin torque has a rotational force and oscillates at a first frequency. The rotational force is exerted on a plane including the first direction and a second direction orthogonal to the first direction. The demodulator is configured to demodulate an output signal received from the magnetism detection element and to detect an intensity of a measurement target magnetic field exerted on the magnetism detection element on the basis of an amplitude of the output signal. The output signal has the first frequency.

Magnetic-field sensors use magnetic closed-loops with magnetic-field sensing elements, e.g., magnetoresistance (MR) elements, and diagnostic circuitry operating in a separate frequency band than that used for magnetic field sensing. The MR elements can be used in a first stage of a high gain amplifier which provides a feedback signal to a feedback coil in a feedback configuration to provide a magnetic feedback field. The magnetic feedback field attenuates the sensed magnetic field so that the MR elements operate in a linear range. Magnetic stray field effects and any limited linearity of magnetic-field sensing elements can be masked by the loop gain of the closed loop. For a magnetic closed-loop, a negative feedback configuration can be used or a positive feedback configuration can be used with a loop-gain of less than one. The diagnostic signal traverses the closed-loop and provides information regarding correct or incorrect functioning of the loop components.

A method of sensing molecules using a detection device, the detection device comprising a plurality of magnetoresistive (MR) sensors and at least one fluidic channel, comprising adding a plurality of molecules to be detected to the at least one fluidic channel, wherein at least some of the plurality of molecules to be detected are coupled to respective magnetic nanoparticles (MNPs), detecting a characteristic of a magnetic noise of a first MR sensor of the plurality of MR sensors, wherein the characteristic of the magnetic noise is influenced by a presence of one or more MNPs in a vicinity of the first MR sensor, and determining, based on the detected characteristic, whether the first MR sensor detected the presence of one or more MNPs in the vicinity of the first MR sensor.

An apparatus for providing a bias current to a hall sensor includes: a bias provider configured to provide the bias current to the hall sensor; and a processor configured to produce a bias current control value based on a node voltage between the hall sensor and the bias provider, wherein the bias provider is configured to vary the bias current based on the bias current control value.

A magnetic sensor suppressing bias magnetic field effects includes a magnetic detecting unit including first to fourth magneto-resistive elements to which a first magnetic field to be detected is applied, a differential amplifier into which the output voltage of the magnetic detecting unit is input, a first magnetic field generating conductor which, by a first feedback current output by the differential amplifier, applies to the magnetic detecting unit a second magnetic field to cancel the first magnetic field detected by the magnetic detecting unit, a bias magnetic field detector which detects a bias magnetic field applied to the magnetic detecting unit and outputs a second feedback current corresponding to the bias magnetic field, and a second magnetic field generating conductor which, by the second negative feedback current, applies to the magnetic detecting unit a correcting magnetic field to cancel the bias magnetic field detected by the magnetic detecting unit.

A cartridge assembly, and method of using the same, is provided. The assembly includes a sample processing card and a substrate attached thereto. The card has an injection port for receiving a test sample; at least one metering chamber; a mixing material source for introducing mixing material(s) to the metering chamber; fluid communication channels fluidly connecting the injection port and the mixing material source to the metering chamber; and at least one output port for delivering the test sample to a sensor (e.g., GMR sensor). The substrate has associated therewith: the sensor for sensing analytes in the test sample; electrical contact portions for an electrical connection with a reader unit; and a memory chip. The assembly further includes a pneumatic interface with port(s) and corresponding communication channel(s) fluidly connected to card. The interface connects with an off-board pneumatic system and enables application of positive and negative pressurized fluid to the card to move the test sample and one or more mixing materials therein and to the sensor.

An angle sensor comprising: a plurality of magnetic field sensing elements configured to detect a magnetic field and generate a respective plurality of analog magnetic field signals; a plurality of analog frontend circuits each analog frontend circuit associated with a respective magnetic field sensing element; and a digital feedback circuit configured to generate digital magnetic field signals from the plurality of analog magnetic field signals and generate digital error correction values, wherein the plurality of analog frontend circuits are configured to obtain the digital error correction values from the digital feedback circuit, generate analog correction values from the digital error correction values, and apply the analog correction values to the plurality of analog magnetic field signals to generate a plurality of corrected analog magnetic field signals.

A magnetic field sensor apparatus includes a sensor signal generator generating a sensor signal responsive to a magnetic field. A switching level provider provides during a power up mode a switching level based on a most recently updated valid one of a first and a second value of a default switching level. If an update triggering condition occurs, the not most recently updated one of the first and second values of the default switching level is updated and the most recently updated one of the first and second values of the default switching level is maintained unchanged until a next update triggering condition occurs, so that the first and second values of the default switching level are updated alternately on consecutive triggering conditions.

A Hall sensor circuit includes a first Hall sensor, a second Hall sensor, a first preamplifier circuit, a second preamplifier circuit, a subtractor circuit, and a duty cycling circuit. The first preamplifier circuit includes an input and an output. The input is coupled to the first Hall sensor. The second preamplifier circuit includes a first input, a second input, and an output. The first input is coupled to the second Hall sensor. The subtractor circuit includes a first input coupled to the output of the first preamplifier circuit, a second input coupled to the output of the second preamplifier circuit, and an output coupled to the second input of the second preamplifier circuit. The duty cycling circuit is coupled to the second preamplifier circuit and the second Hall sensor.