Allegro Microsystems, LLC

Jeffrey Eagen

Paul A David

Rémy Lassalle-Balier

Andrea Foletto

Damien Dehu

William P Taylor

Paolo Campiglio

Maxime Rioult

Maxim Klebanov

Yannick Vuillermet

Eric G Shoemaker

Noémie Belin

According to an embodiment, a magnetic field sensor includes: one or more magnetic field sensing elements; and a magnet structure to provide a bias magnetic field about the one or more magnetic field sensing elements, the magnet structure includes alternating magnetic layers and non-magnetic layers with at least three magnetic layers.

Magnet structure for back-biased sensors

In one aspect, a dual double-pinned spin valve element includes a first spin valve that includes a first pinned layer and a second pinned layer and a second spin valve disposed on the first spin valve and comprising a third pinned layer and a fourth pinned layer. The first, second, third and fourth pinned layers each have a magnetization in a first direction.

Dual double-pinned spin valve element having magnet bias with increased linear range

Methods and apparatus that can include a rotatable target to generate a sinusoidal signal in a magnetic field sensor, wherein the target includes a plurality of sinusoidal teeth to reduce angular error. A magnetic field sensor can be configured to determine a position of the target. In embodiments, a rotatable target to generate a sinusoidal signal in a magnetic field sensor can include a plurality of sinusoidal teeth and a number of harmonics to reduce angular error.

Magnetic field sensor

Methods and apparatus for a magnetic field sensor for measuring movement of a target including a substrate and a magnet. A first bridge structure has first and second pluralities of magnetic field sensing elements spaced from each other. An axis of sensitivity of the magnetic field sensing elements is rotated at a predetermined angle with respect to an axis of rotation of the target to generate an output signal corresponding to the position of the target and a change in a property of the magnetic field generated by the magnet.

A system includes a ring magnet having magnetic segments and configured to rotate about an axis of rotation, wherein adjacent segments have different magnetic polarities, The system can further include a substrate positioned so that a top surface of the substrate is substantially parallel to the axis of rotation and a center plane passing through the ring magnet and perpendicular to the axis of rotation of the ring magnet intersects the top surface at an intersection line. The system can further include four magnetic field sensing elements supported by the substrate and electrically coupled to form a first bridge circuit, wherein two of the four magnetic field sensing elements are positioned on one side of the intersection line and the other two of the four magnetic field sensing elements are positioned on the other side of the intersection line.

Magnetic field sensor with stray field immunity and large air gap performance

A magnetic field sensor is provided, including a substrate, a first bridge circuit formed on the substrate, the first bridge circuit being arranged to generate a first signal indicative of a motion of a target, and a second bridge circuit formed on the substrate, the second bridge circuit being arranged to generate a second signal indicative of whether the magnetic field sensor is aligned with the target.

Target alignment and stray field indicator

A magnetoresistance (MR) element includes a first stack portion comprising a first plurality of layers including a first spacer layer having a first thickness and a first material selected to result in the first stack portion having a first sensitivity to the applied magnetic field. The MR element also has a second stack portion comprising a second plurality of layers, including a second spacer layer having a second thickness to result in the second stack portion having a second sensitivity to the applied magnetic field. The first thickness may be different than the second thickness resulting in the first sensitivity being different than the second sensitivity.

Magnetoresistance element with increased operational range

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.

A method of determining an error condition in a magnetic field sensor can include receiving a first bridge signal, the first bridge signal generated by a first full bridge circuit. The method can also include receiving a second bridge signal, the second bridge signal generated by a second full bridge circuit. The method can also include determining a bridge separation from the first bridge signal and the second bridge signal. The method can also include comparing a function of the bridge separation to a threshold value. The method can also include generating an error signal indicative of the error condition or not indicative of the error condition in response to the comparing.

Magnetic field sensor able to identify an error condition

A magnetic field sensor can include four magnetoresistance elements arranged in a bridge, wherein two of the magnetoresistance elements have a response to an external or stray magnetic field that is opposite to a response of the other two magnetoresistance elements.

Magnetic field sensor with magnetoresistance elements arranged in a bridge and having a common reference direction and opposite bias directions

Methods and apparatus for s sensor having magnetic field sensing elements coupled in a differential bridge and a signal processor configured to receive signals from the bridge to determine a distance from the magnetic field sensing elements to a magnet from flux line divergence of magnetic flux generated by the magnet.

Magnetic field sensor using MR elements for detecting flux line divergence

A magnetic field sensor for sensing a movement of a target object an include a substrate having a major planar surface and three or more magnetic field sensing elements disposed upon the major planar surface of the substrate. The three or more magnetic field sensing elements can have respective major response axes, each major response axis parallel to the major planar surface of the substrate. The three or more magnetic field sensing elements comprise first and third magnetic field sensing elements and a second magnetic field sensing element disposed between the first and third magnetic field sensing elements. A first spacing between the first and second magnetic field sensing elements is less than a second spacing between the second and third magnetic field sensing elements. No other magnetic field sensing elements are disposed between the first and third magnetoresistance elements.

Magnetic field sensor having unequally spaced magnetic field sensing elements

Methods and apparatus for a sensor system having a first magnetic field sensing element with first and second segments where the first and second segments are located at positions to generate magnetic field bias in opposite directions for reducing sensitivity due to misalignment of the first and second segments. A processing module is configured to receive an output of the magnetic field sensing element.

Magnetic field sensor having compensation for magnetic field sensing element placement

A magnetic field sensor includes a substrate having a surface and a plurality of magnetoresistance elements supported by the surface of the substrate. Each magnetoresistance element has a respective width parallel to the surface, and each width may be a smallest dimension parallel to the surface. A first width of a first magnetoresistance element of the plurality of magnetoresistance elements may be different from a second width of a second magnetoresistance element of the plurality of magnetoresistance elements. A processing circuit may be coupled to the plurality of magnetoresistance elements to receive a signal representing a detected magnetic field from at least one of the magnetoresistance elements.

Growing community of inventors

Manchester, NH, United States of America

Jeffrey Eagen