Everspin Technologies, Inc.

Robert Bosch G.m.b.h.

Phillip G Mather

Jon Michael Slaughter

Nicholas David Rizzo

Bradley Neal Engel

Renu Whig

Sanjeev Aggarwal

Kenneth H Smith

Anuraag Mohan

Lianjun Liu

Guido De Sandre

Srinivas V Pietambaram

Jijun Sun

Frederick B Mancoff

Renu Whig Dave

Brian R Butcher

Brad Engel

Young Sir Chung

Carlo Alberto Romani

Johannes Artzner

Martin Maschmann

Cheng-Han Yang

Boris Livshitz

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

In one embodiment, a magnetoresistive (MR) magnetic field sensor system includes a MR magnetic field sensor bridge. The MF magnetic field sensor bridge includes a sense leg with a sense element with a first layer with a first fixed magnetization orientation and, a second layer with a first free magnetization orientation, the first free magnetization orientation orthogonal to the first fixed magnetization orientation at a zero applied magnetic field. A reference leg of the MF magnetic field sensor bridge is electronically connected in parallel to the sense leg. The reference leg includes at least one reference element with a third layer with a second fixed magnetization orientation parallel to, and in the same direction as, the first fixed magnetization orientation, and a fourth layer with a second free magnetization orientation, the second free magnetization orientation parallel to the first fixed magnetization orientation at the zero applied magnetic field.

Magnetoresistive magnetic field sensor bridge with compensated cross-axis effect

A magnetic field sensor structure includes a magnetoresistive sensor assembly and a transistor assembly. A dielectric layer is deposited on the transistor assembly. The dielectric layer includes a trench that exposes an interconnect of the transistor assembly. A damascene process is performed to form an ultra-thick metal (UTM) layer within the trench to create a first metal coil. The first metal coil is configured as a first reset component. Another dielectric layer is formed on the first metal coil. A flux guide is formed within the another dielectric layer. A second metal coil is formed over the another dielectric layer. The second metal coil is configured as a second reset component. The first reset component and the second reset component are configured as a reset mechanism, which is responsive to the transistor assembly and operable to magnetize the flux guide to a predetermined orientation.

Magnetic field sensor with flux guide reset

A chopping technique, and associated structure, is implemented to cancel the magnetic 1/f noise contribution in a Tunneling Magnetoresistance (TMR) field sensor. The TMR field sensor includes a first bridge circuit including multiple TMR elements to sense a magnetic field and a second circuit to apply a bipolar current pulse adjacent to each TMR element. The current lines are serially or sequentially connected to a current source to receive the bipolar current pulse. The field sensor has an output including a high output and a low output in response to the bipolar pulse. This asymmetric response allows a chopping technique for 1/f noise reduction in the field sensor.

Bipolar chopping for 1/f noise and offset reduction in magnetic field sensors

A semiconductor process integrates three bridge circuits, each include magnetoresistive sensors coupled as a Wheatstone bridge on a single chip to sense a magnetic field in three orthogonal directions. The process includes various deposition and etch steps forming the magnetoresistive sensors and a plurality of flux guides on one of the three bridge circuits for transferring a 'Z' axis magnetic field onto sensors orientated in the XY plane.

Methods of manufacturing a magnetic field sensor

A magnetic field sensor array includes a plurality of sensor segments, each including a plurality of magnetic field sensors. A magnetizing current conductor is situated so as to run in the area of the magnetic field sensors in such a way that elements of the magnetic field sensors may be magnetized. A plurality of parallel-connected half-bridges, each including a high switch pand a low switch n, each include a center tap connection situated between the switches. The magnetizing current conductor is connected to each center tap connection, by means of which the magnetizing current conductor is divided into separately activatable magnetizing segments. Elements of a sensor segment are magnetized in that two switches nand phaving different electrical potentials, or alternatively pand n, of two directly adjacent half-bridges are closed simultaneously. At least one further switch nor por alternatively por nis closed.

Method and system for magnetizing elements of a magnetic field sensor array

Three bridge circuits (), each include magnetoresistive sensors coupled as a Wheatstone bridge () to sense a magnetic field () in three orthogonal directions () that are set with a single pinning material deposition and bulk wafer setting procedure. One of the three bridge circuits () includes a first magnetoresistive sensor () comprising a first sensing element () disposed on a pinned layer (), the first sensing element () having first and second edges and first and second sides, and a first flux guide () disposed non-parallel to the first side of the substrate and having an end that is proximate to the first edge and on the first side of the first sensing element (). An optional second flux guide () may be disposed non-parallel to the first side of the substrate and having an end that is proximate to the second edge and the second side of the first sensing element ().

Three axis magnetic field sensor

A sensor structure includes sensing elements, a flux guide, and a flux guide reset mechanism. The flux guide is configured to guide magnetic flux in a plane for detection by the sensing elements. The flux guide reset mechanism is configured to set the flux guide to a predetermined magnetic orientation. The flux guide reset mechanism includes at least a first coil and a second coil. The first coil is configured to generate a first magnetic field. The first coil includes first coil segments. The second coil is configured to generate a second magnetic field. The second coil includes second coil segments. The flux guide is disposed between the first coil and the second coil. The first coil segments and the second coil segments are configured such that a first magnetic field profile of the first magnetic field is coherent with a second magnetic field profile of the second magnetic field with respect to at least at a region of the flux guide that overlaps the sensing elements.

Magnetic field sensor with optimized coil configurations for flux guide reset

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.

Growing community of inventors

Phoenix, AZ, United States of America

Phillip G Mather