Allegro Microsystems, LLC

Commissariat a L'energie Atomique Et Aux Energies Alternatives

Hernán D Romero

Octavio H Alpago

Gerardo A Monreal

Alexander Latham

Juan Manuel Cesaretti

Ezequiel Alves

Bryan Cadugan

Claude Fermon

Jay M Towne

David Jamie Haas

Myriam Pannetier-Lecoeur

Bruno Luis Uberti

Karl Scheller

Jason Boudreau

Franco Noel Martin Pirchio

Pablo Aguirre

Craig S Petrie

Alejandro Gabriel Milesi

Alberto Bilotti

Nicolas Rigoni

Cory Voisine

Jeff Eagen

Nicolás Rafael Biberidis

Martin Drinovsky

Ricardo Scheinkerman

Roman Prochazka

Maria C Costa

Conrado Rossi

A system, comprising: a sensing element including a plurality of resistive elements; a switching matrix that is configured to change a total resistance of the sensing element by bringing online or offline one or more of the plurality of resistive elements, the total resistance of the sensing element, at any point in time, being based on respective resistances of only those of the plurality of resistive elements that are currently online; a matrix controller that is configured to detect when a value of a counter signal is updated and cause the switching matrix to change the total resistance of the sensing element by bringing offline or online one or more of the plurality of resistive elements based on the value of the counter signal; and a counter signal generator configured to detect whether an offset signal satisfies a predetermined condition and update the value of the counter signal.

Low residual offset sensor

In one example, an inductive sensor interface circuit includes: a coil driver configured to excite one or more transmit coils to generate a magnetic field at a target; a plurality of input channels for receiving input signals via respective ones of a plurality of receive coils, the input signals responsive to reflections of the magnetic field off the target and encoding information about a position of the target; a position detection processor to decode the information about the position of the target from the input signals; and an amplitude detection processor configured to calculate an amplitude of the input signals and to control a strength of the magnetic field generated by the coil driver based on a difference between the calculated amplitude to a predetermined desired input amplitude.

Adaptive coil driver for inductive sensors

A sensor, comprising: a substrate having a reference crystal orientation and a plurality of vertical Hall element pairs that are formed on the substrate. Each vertical Hall element pair includes: (i) a respective first vertical Hall element that is oriented at a respective first angle relative to the reference crystal orientation of the substrate and (ii) a respective second vertical Hall element that is oriented at a respective second angle relative to the reference crystal orientation of the substrate. The substrate has a rectangular shape, and each of the vertical Hall element pairs is disposed in a different respective corner of the substrate.

Stray field immune angle sensor

Systems, circuits, and methods provide self-calibration for magnetoresistance-based magnetic field sensors. Examples can include use of a closed loop acting as a feedback or calibration loop that is configured to process a reference signal applied to one or more magnetoresistance elements in a MR-based magnetic field sensor that also detects one or more external magnetic fields. The closed loop can adjust a bias voltage applied to the one or more magnetoresistance elements based on the reference signal. The calibration loop can accordingly provide for automatic or self-calibration of sensitivity of one or more magnetoresistance elements of the sensors to compensate for external factors affecting sensitivity of the one or more magnetoresistance elements.

Self-calibrating magnetoresistance-based magnetic field sensors

Magnetic field sensors having at least two bridges including MR elements are described. MR elements of each bridge have different magnetic reference directions. A first bridge is positioned to sense a first uniform magnetic field of a first polarity and a second bridge is positioned to sense a second uniform magnetic field of a second polarity opposite to the first polarity. The first and second uniform magnetic fields make up a differential field of interest. The described magnetic field sensors sense the field of interest in a manner that is immune to stray fields. Dual signal path embodiments are described in which outputs of the two bridges are independently processed and single signal path embodiments include a single signal path for processing the output of a combined (e.g., parallel) bridge arrangement.

Magnetoresistance bridge circuits with stray field immunity

A method is provided for use in a sensor, the method comprising: selecting a switching cycle for the sensor; transitioning the sensor into a state in which at least one component of the sensor is periodically turned on and off in accordance with the switching cycle; sampling an analog signal to generate a sampled signal, the analog signal being generated by at least one sensing element, the analog signal being sampled only during periods in which the at least one component of the sensor is turned on; and generating an output signal based, at least in part, on the sampled signal and outputting the output signal.

Adaptive switching frequency selection

An amplifier circuits inductive/magnetic sensor interface can include a main signal path including one or more amplifiers configured to receive an input signal and to produce an output signal based on the input signal. The input signal may include a square-wave demodulated signal having an associated modulation frequency and an undesired frequency component at twice the modulation frequency of the square-wave demodulated signal. The amplifier circuit may include a gain feedback loop configured to set a gain of the amplifier circuit. The amplifier circuit may include a ripple reduction feedback loop configured to receive an intermediate signal on the main signal path and extract the undesired frequency component of the intermediate signal to produce a filtered version of the intermediate signal and provide the filtered version of the intermediate signal to the main signal path.

Inductive interface circuits having ripple-reduction loops

Magnetic field closed loop sensors including offset reduction circuitry to reduce undesired baseband components attributable to offset associated with magnetoresistance elements are described. A superimposed signal including a main signal portion indicative of a parameter of a target and an offset reduced signal portion is coupled to feedback circuitry. The feedback circuitry generates a feedback signal to drive a feedback coil. Main processing circuitry is operative to extract the main signal portion from the superimposed signal and produce a sensor output signal based on the main signal portion. Example offset reduction circuitry can take the form of AC coupling circuitry or a ripple reduction loop.

Magnetic field closed loop sensors with offset reduction

In one aspect, bridge circuitry includes a first magnetoresistance (MR) element connected with a second MR element at a first node; a third MR element connected with the first MR element at a second node; a fourth MR element connected with the third MR element at a third node; a fifth MR element connected with a sixth MR element at a fourth node; a seventh MR element connected with the fifth MR element at a fifth node; and an eighth MR element connected with the seventh MR element at a sixth node; and a plurality of eight switches. Six of the plurality of eight switches are each connected to a corresponding one node.

Electrical offset compensating in a bridge using more than four magnetoresistance elements

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.

Magnetic-field closed-loop sensors with diagnostics

A magnetic field sensor can be are based upon three element vertical Hall element building blocks, e.g., three element or six element vertical Hall element arrangements, all arranged in a circle. In some embodiments, the circle of vertical Hall elements can be arranged as a CVH sensing element.

Circuit for reducing an offset component of a plurality of vertical hall elements arranged in one or more circles

A magnetic field sensor includes at least one coil responsive to an AC coil drive signal; at least one magnetic field sensing element responsive to a sensing element drive signal and configured to detect a directly coupled magnetic field generated by the at least one coil and to generate a magnetic field signal in response to the directly coupled magnetic field; a processor responsive to the magnetic field signal to compute a sensitivity value associated with detection of the directly coupled magnetic field and substantially independent of a reflected magnetic field reflected by a conductive target disposed proximate to the at least one magnetic field sensing element; and an output signal generator configured to generate an output signal of the magnetic field sensor indicative of the reflected magnetic field.

Coil actuated sensor with sensitivity detection

Methods and apparatus for linear inductive torque sensing that may include transmitting an AC magnetic field with a transmit coil toward a conductive target and receiving a field reflected by the conductive target with a receive coil, wherein the conductive target comprises first and second targets positioned with respect to each other and each shaped to linearly increase or decrease an amount of conductive area of the conductive target due to relative movement of the first and second targets which changes an amount of the field reflected by the conductive target. A signal from the receive coil can be processed to determine a relative position of the first and second targets corresponding to an amount of torque on an elongate member connected to the first and second targets. In other embodiments, a change in inductance of the transmit coil is measured to determine relative target position.

Linear inductive torque sensor

In one aspect, a magnetic-field sensor includes main coil circuitry configured to generate a first magnetic field signal at a first frequency. A reflected signal is generated from a target caused by the first signal generated by the main coil circuitry. The magnetic field sensor also includes magnetoresistance circuitry configured to receive an error signal. The error signal is formed from a combination of the reflected signal and a second magnetic field signal. The magnetic-field sensor further includes analog circuitry configured to receive an output signal from the magnetoresistance circuitry, digital circuitry configured to receive an output signal from the analog circuitry, a mixer configured to receive a feedback signal from one of the digital circuitry or the analog circuitry, and secondary coil circuitry configured to receive a driver signal from the mixer causing the secondary coil circuitry to generate the second magnetic field signal at the first frequency.

Reducing stray magnetic-field effects using a magnetic-field closed-loop system

In one aspect, bridge circuitry includes a first magnetoresistance (MR) element; a second MR element connected in series with the first MR element at a first node; a third MR element; a fourth MR element connected in series with the third MR element at a second node; a first switch connected at one end to a supply voltage and connected at the other end to the third MR element; a second switch connected at one end to ground and connected at the other end to the fourth MR element; a third switch connected at one end to ground and connected at the other end to the third MR element and the first switch; and a fourth switch connected at one end to the supply voltage and the other end to the fourth MR element and the second switch. The first and second MR elements are in parallel with the third and fourth MR elements.

Growing community of inventors

Buenos Aires, Argentina

Hernán D Romero