Abstract: An apparatus and a method provide an output signal indicative of a speed of rotation and/or a direction of movement of a ferromagnetic object having ferromagnetic features and capable of moving. A variety of signal formats of the output signal are described, each of which have pulses at a rate faster than the ferromagnetic features pass by the magnetic field sensor. The magnetic field sensor includes a plurality of diagnostic circuits that detect a failure of the magnetic field sensor and output a diagnostic signal indicative of the failure. The controller can receive the diagnostic signals and generate a sensor output signal including a failure state to indicate the detected failure.

Abstract: An apparatus comprises a first substrate and two coils supported by the first substrate and arranged next to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils. One or more magnetic field sensing elements are positioned in the area between the coils and configured to detect the reflected magnetic field.

Abstract: Methods and apparatus for bi-directional communication between first and second die of a signal isolator for feedback and/or diagnostic signals. In embodiments, the first and second die can be matched.

Abstract: Method and apparatus for providing error compensation for a magnetic field sensing element in a three-phase motor. In embodiments, a driving angle is determined from zero-crossings of the magnet pole-pairs and error compensation levels for the pole-pairs is determined to reduce distortions in the motor current waveform.

Abstract: An electronic circuit includes a driver circuit having an output terminal that can be coupled to a load to drive the load. A control circuit is coupled to the driver circuit for controlling the driver circuit. A transistor is coupled in series between the driver circuit and the output terminal. The transistor has a first terminal coupled to the driver circuit and a second terminal coupled to the output terminal. A biasing circuit is coupled to a gate terminal of the transistor and configured to provide a constant voltage to the gate terminal to bias the transistor to a conducting state to reduce the susceptibility of the electronic circuit to electromagnetic interference. The biasing circuit includes a voltage regulator, a Zener diode, and a capacitor. The Zener diode and capacitor are coupled to the gate terminal and a reference terminal.

Abstract: Systems and methods described herein provide a current sensor having fault detection circuitry configured to detect over-current and/or current faults corresponding to current through a conductor being greater than a predetermined level. The current sensor can include a shared signal path, a main signal path, and a fault detection signal path to perform both fault detection and current detection signal processing. The current sensor can include one or more magnetic field sensing elements configured to generate a magnetic field signal indicative of the current through the conductor, an analog-to-digital converter (ADC) configured to receive the magnetic field signal and convert the magnetic field signal into a digital signal, and a fault detector responsive to the digital signal to generate a fault signal indicative of the current through the conductor being greater than a predetermined level.

Abstract: A buffer amplifier comprises a source follower and a feedback amplifier. The feedback amplifier may be configured to control a drain current of the source follower to remain substantially constant independent of a load.

Abstract: An apparatus comprises a conductive material having varying thickness along its length, the varying thickness providing varying response along a length of the conductive material to a magnetic field having a non-zero frequency; wherein the magnetic field produces an eddy current in the conductive material which generates a reflected magnetic field, wherein the varying response causes the reflected magnetic field to vary in strength along the length of the conductive material. The apparatus may include one or more reference portions of conductive material.

Abstract: A magnetoresistance structure includes a base that includes a conductive layer and a first active element on and in direct contact with the conductive layer. The magnetoresistance structure also includes a pillar structure connected to the base. The pillar structure includes a first hard mask, a capping material, a second active element and a tunnel layer. The magnetoresistance structure also further includes an etching barrier deposited on the pillar and the base; a second hard mask deposited on the etching barrier; and a capping barrier deposited on the second hard mask and covering side walls of the base.

Abstract: A sensor integrated circuit includes a disturb immune memory configured to store data and a digital processor coupled to the disturb immune memory and including a main register. The digital processor is configured to perform one of a fast reset or slow reset of the main register according to a level of a supply voltage to the integrated circuit. The fast reset includes resetting the main register according to the data stored in the disturb immune memory and the slow reset includes resetting the main register according to a default state.

Abstract: Apparatus including a regulator configured to generate a regulated output and a diagnostic circuit configured to generate a diagnostic signal indicative of whether the regulator is able to maintain regulation is described. The regulator includes an amplifier having a first input responsive to a reference voltage, a second input responsive to a feedback signal associated with the regulated output, and an output at which a control voltage is provided and further includes a pass element controlled by the control voltage and coupled to a node which the regulated output is provided. The diagnostic circuit is responsive to the control voltage and to the reference voltage to generate the diagnostic signal. The regulator may be a voltage regulator or a current regulator and in some embodiments, the diagnostic signal takes the form of a composite signal indicative of whether a voltage regulator and whether a current regulator can maintain regulation.

Abstract: A sensor integrated circuit can include sensors with differing levels of sensitivity, a first processing channel that responds to a first analog signal generated by a first sensor to generate a first processed signal, and a second processing channel that responds to a second analog signal generated by the second sensor to generate a second processed signal. Where the first sensor can include a pressure or optical sensing element, and the second sensor can include a pressure or optical sensing element. A checker circuit uses the processed signals to detect faults in the sensor integrated circuit.

Abstract: A sensor is provided having a magnetic field sensing element to generate a magnetic field signal, a switching circuit coupled to receive the magnetic field signal and generate a switching signal that changes a polarity of the magnetic field signal at a predetermined frequency, and a comparison device configured to receive the switching signal and generate an output signal that changes a level in response to the switching signal crossing a predetermined threshold. The switching circuit is disposed between the magnetic field sensing element and the comparison device and can provide the comparison device an input signal (i.e., the switching signal) that changes polarity at the predetermined frequency. The comparison device can sense characteristics, such as but not limited to crossing operate and release threshold levels, of both north and south polarity magnetic field signals using the switching signal.

Abstract: A magnetic field sensor can include a magnetic field sensor can include a substrate having a major surface in an x-y plane with an x axis and a y axis. The magnetic field sensor can also have an external field sensing circuit disposed upon the substrate and responsive to an external magnetic field generated outside of the magnetic field sensor. The external field sensing circuit can include one or more magnetoresistance elements, each having a respective reference layer with a magnetic direction parallel to the y axis and in the x-y plane. The one or more magnetoresistance elements can be operable to generate a magnetoresistance element signal responsive to the external magnetic field.

Abstract: A magnetic field sensor can include a substrate disposed in an x-y plane with x and y axes; one or more magnetoresistance elements, wherein magnetic directions of reference layers of each of the one or more magnetoresistance elements are parallel to the x axis; wherein the one or more magnetoresistance elements are operable to generate a magnetoresistance element signal; a first current conductor operable to generate a first AC magnetic field in an x-direction and a second current conductor operable to generate a second AC magnetic field in a y-direction; and a component determination circuit comprising at least two of: a first demodulator to demodulate the magnetoresistance element signal with a first clock signal with a first frequency, a second demodulator coupled to demodulate the magnetoresistance element signal with the first clock signal or with a second clock signal with a second frequency, or a low pass filter operable to filter the magnetoresistance element signal.

Abstract: A magnetic field sensor includes one or more magnetic field sensing elements and a back-biased magnet arranged to avoid saturation of the one or more magnetic field sensing elements, particularly when the one or more magnetic field sensing elements comprise one or more magnetoresistance elements. The one or more magnetoresistance elements can be arranged in a resistor bridge.

Abstract: Methods and apparatus for a signal isolator having a dielectric interposer supporting first and second die each having a magnetic field sensing element. A first signal path extends from the first die to the second die and a second signal path extends from the second die to the first die. In embodiments, the first signal path is located in the interposer and includes a first coil to generate a magnetic field and the second signal path is located in the interposer and includes a second coil to generate a magnetic filed. The first coil is located in relation to the second magnetic field sensing element of the second die and the second coil is located in relation to the first magnetic field sensing element of the first die.

Abstract: A magnetoresistance element deposited upon a substrate includes a first stack portion having opposing first and second surfaces and including a first plurality of layers. The first stack portion has a first substantially linear response corresponding to an applied magnetic field over a first magnetic field strength range. The magnetoresistance element also includes a second stack portion having opposing first and second surfaces and including a second plurality of layers. The first surface of the second stack portion is disposed over the second surface of the first stack portion and the second stack portion has a second substantially linear response that is different than the first substantially linear response. The second substantially linear response corresponds to the applied magnetic field over a second magnetic field strength range.

Abstract: An apparatus comprises a first measurement circuit having a first magnetic field sensing element to detect a measured magnetic field and produce a first signal representing the measured magnetic field, and a first signal processing circuit to process the first signal to produce a first processed signal. A second measurement circuit comprises a second magnetic field sensing element to detect a measured magnetic field and produce a second signal representing the measured magnetic field, and a second signal processing circuit to process the second signal to produce a second processed signal. A diagnostic processing circuit is coupled to receive the first signal and the second signal and configured to process the first signal during a first time period to produce a first diagnostic signal, and process the second signal during a second time period. A logic circuit determines if an error is present.

Abstract: A magnetic field sensor including at least one magnetic field sensing element configured to generate a magnetic field signal indicative of a magnetic field associated with a target and a detector responsive to the magnetic field signal and to a threshold level to generate a sensor output signal containing transitions associated with features of the target in response to the magnetic field signal crossing the threshold level further includes a threshold generator to generate an adaptive threshold. The threshold generator is configured to generate the threshold level to achieve a predetermined fixed hard offset and that adapts with a variation in the airgap in order to minimize an error between times or angles of the transitions of the sensor output signal over the variation in the airgap.