Texas Instruments Corporation

Everspin Technologies, Inc.

National Semiconductor Corporation

Robert Boschgmbh

Allegro Microsystems, LLC

Crocus Technology Inc.

Anuraag Mohan

Phillip G Mather

Peter J Hopper

William David French

Peter Smeys

Dok Won Lee

Erika Lynn Mazotti

Guido De Sandre

Peter B Johnson

Andrei Papou

Terry Dyer

Ubol Udompanyavit

Robert Zucker

Various means for improvement in signal-to-noise ratio (SNR) for a magnetic field sensor are disclosed for low power and high resolution magnetic sensing. The improvements may be done by reducing parasitic effects, increasing sense element packing density, interleaving a Z-axis layout to reduce a subtractive effect, and optimizing an alignment between a Z-axis sense element and a flux guide, etc.

Magnetic field sensor with increased SNR

Disclosed is a MTJ sensing circuit for measuring an external magnetic field and including a plurality of MTJ sensor elements connected in a bridge configuration, the MTJ sensing circuit having an input for inputting a bias voltage and generating an output voltage proportional to the external magnetic field multiplied by the bias voltage and a gain sensitivity of the MTJ sensing circuit, wherein the gain sensitivity and the output voltage vary with temperature; the MTJ sensing circuit further including a temperature compensation circuit configured to provide a modulated bias voltage that varies as a function of temperature over a temperature range, such that the output voltage is substantially constant as a function of temperature. Also disclosed is a method for compensating the output voltage for temperature.

Temperature compensated MTJ-based sensing circuit for measuring an external magnetic field

An out-of-plane tunneling magnetoresistive (TMR) magnetic field sensor includes a sense element that defines a sense plane and a flux guide configured to direct a magnetic field perpendicular to the sense plane into the sense plane. The magnetic field sensor further includes a first coil arranged in a first plane, a second coil electrically insulated from the first coil and arranged in a spaced-apart second plane, and drive circuitry operatively connected to the first coil and the second coil. The drive circuitry in a first mode energizes the first and second coils to generate respective first and second fields that combine to set a magnetization of the flux guide. The drive circuitry in a second mode energizes only the first coil to generate the first field so as to set a magnetization of the sense element without changing the magnetization of the flux guide.

Z-axis magnetic sensor with distributed flux guides

A circuit has a magnetic sensor that produces an uncompensated magnetic sensor output signal. A temperature sensor produces an ambient temperature signal. A compensation circuit is connected to the magnetic sensor and the temperature sensor. The compensation circuit is configured to add a computed temperature compensation signal to the uncompensated magnetic sensor output signal to produce a magnetic sensor temperature compensated output signal that reduces thermally induced variation of the uncompensated magnetic sensor output signal.

Apparatus and method for magnetic sensor output compensation based upon ambient temperature

An electromagnetic sensing device with a package substrate, a first die mounted on the package substrate, and a second die mounted on the package substrate. The first die includes a first integrated circuit and a first magnetic core formed above the first integrated circuit. The first magnetic core has a first sensing axis parallel to a planar surface of the package substrate. The second die includes a second integrated circuit and a second magnetic core formed above the second integrated circuit. The second magnetic core has a second sensing axis orthogonal to the planar surface of the package substrate.

Integrated fluxgate device with three-dimensional sensing

A magnetic field sensor includes built-in self-test coils in a configuration to provide magnetic field stimulation along three axes, with a high field factor, and thus, reduce a power budget of the sensor and physical size of the self-test coils. The magnetic field sensor comprises a first bridge circuit including a plurality of sense elements configured to sense a magnetic field. The magnetic field sensor further comprises re-configurable self-test current lines coupled to a self-test source to perform high field, high power wafer and die level testing and trim, as well as low power in-situ characterization and calibration of the sensor. The self-test current lines may be routed to form a coil with multiple turns around the TMR elements.

Magnetic field sensor with 3-axes self test

A method of fabricating fluxgate devices to measure the magnetic field in two orthogonal, in plane directions, by using a composite-anisotropic magnetic core structure.

Integrated dual axis fluxgate sensor using double deposition of magnetic material

In one embodiment, a TMR field sensor utilizes existing one or more self-test current lines in a configuration to extend magnetic field measurement range without sacrificing measurement sensitivity. The self-test current lines are energized to facilitate magnetic field measurement when the measured magnetic field reaches a threshold. The magnetic field created by self-test coil opposes an external magnetic field being measured to keep the net magnetic field within a desired range where the magnetic field sensor has linear output and desired sensitivity.

Magnetic field sensor with increased field range

A fluxgate magnetometer is formed in a semiconductor wafer fabrication sequence, which significantly reduces the size and cost of the fluxgate magnetometer. The semiconductor wafer fabrication sequence attaches a die, which has drive and sense circuits, to the bottom surface of a cavity formed in a larger structure, and forms drive and sense coils around a magnetic core structure on the top surface of the larger structure.

Semiconductor fluxgate magnetometer

A giant magneto-impedance (GMI) magnetometer is formed in a semiconductor wafer fabrication sequence, which significantly reduces the size and cost of the GMI magnetometer. The semiconductor wafer fabrication sequence forms a magnetic conductor, a non-magnetic conductor that is wrapped around the magnetic conductor as a coil, and non-magnetic conductors that touch the opposite ends of the magnetic conductor.

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Fremont, CA, United States of America

Anuraag Mohan