Torsionally insensitive mounting of differential sensor with direction detection

Abstract

Embodiments of the present disclosure generally relate to a twist-insensitive mounting differential sensor with direction detection. A magnetic sensor includes a plurality of pairs of sensor elements and a sensor circuit, each pair of sensor elements including two sensor elements disposed opposite one another on a circumference of a circle arranged in a sensor plane of the magnetic sensor, the sensor circuit configured to generate a first pulse output signal based on a selected differential measurement signal indicative of a rotational speed of an object. The sensor circuit is configured to generate a plurality of differential measurement signals, one for each of the plurality of pairs of sensor elements, wherein each of the plurality of differential measurement signals is derived from sensor signals generated by the corresponding pair of sensor elements. The sensor circuit is further configured to select, as the selected differential measurement signal, the differential measurement signal having a largest amplitude from the plurality of differential measurement signals.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a twist-insensitive mounted differential sensor with direction detection. BACKGROUND

[0002] To measure wheel speed (e.g. in automotive applications), ferromagnetic wheels are typically used in combination with a magnetically sensitive sensor and a magnet mounted to the sensor. The sensor generates output pulses. A control unit counts the pulses and is able to calculate the wheel speed and the actual angle of a rotating wheel and optionally determine the direction of rotation of the wheel.

[0003] In camshaft sensing applications, a Hall single cell configuration can be used that enables output switching at the tooth rim of a gear wheel. A z-magnetized back biased sensor in combination with a Bz-sensitive single cell sensor generates a sinusoidal signal when a ferromagnetic target wheel is rotating in front of the sensor. The maximum amplitude is achieved when a tooth passes the sensor, while the minimum signal is achieved when the sensor faces the notch of the gear wheel. Thus, the sensor device switches at the tooth rim.

[0004] One benefit of using a Hall single cell sensor is that the sensor is twist-insensitive, such that the sensor will work independent of the rotational orientation of its z-axis. Thus, the air gap between the sensor module and the wheel can be adjusted during installation using a screw. That is, twisting the sensor module like a screw will adjust the air gap and the rotational orientation of the sensor can be ignored. Thus, during installation of the sensor, the assembly tolerances are relaxed due to the twist-insensitivity.

[0005] On the downside, Hall single cell sensors have a disadvantage in terms of stray field robustness. A stray field is a magnetic field introduced by external means located in the near environment of the sensor. For example, components located within a vehicle (e.g. for hybrid cars, due to current rails driving high currents close to the sensing device or due to sensing battery charging) or currents flowing through a railway of a train system generating a magnetic field can cause stray field disturbances.

[0006] As an alternative to a Hall single cell sensor, differential Hall sensing elements can be used to increase the stray field robustness. In a differential Hall sensor, two Hall plates are separated. The output signal is calculated by subtracting the Bz signal of the second Hall plate from the Bz signal of the first Hall plate and due to the differential calculation, a uniform stray field in the z-direction will be cancelled out.

[0007] The differential Hall signal has a signal maximum at the rising edge of a wheel tooth and a signal minimum at the falling edge of a wheel tooth. Thus, the output of the differential Hall sensor switches at the tooth center and the notch center compared to the Hall single cell sensor.

[0008] However, due to the switching point difference, the electronic control unit (ECU) of the vehicle needs to be reconfigured to adjust the switching point. Furthermore, another disadvantage of the differential Hall sensor is that it is not sensitive to twist. Twisting the sensor module around its z-axis will result in a signal attenuation. The worst case is a twist angle of 90°, at which both Hall plates sense the same Bzfield. In this case, there is no differential signal available, and the sensor cannot detect a tooth or a notch.

[0009] Accordingly, there can be a need for an improved device that is both robust to stray fields and insensitive to twist, i.e., twist independent. SUMMARY

[0010] A magnetic sensor module, system, and method configured to detect a rotation of an object and more specifically a rotational speed of the object are provided.

[0011] One or more embodiments provide a magnetic sensor configured to detect a rotation of an object. The magnetic sensor comprises a plurality of sensor elements arranged in a sensor plane of the magnetic sensor, wherein the plurality of sensor elements is configured to generate a plurality of sensor signals in response to sensing an oscillating magnetic field modulated by the rotation of the object, wherein each sensor signal is generated by one of the plurality of sensor elements, wherein the plurality of sensor elements is arranged on a circumference of a circle, wherein the plurality of sensor elements is grouped into a plurality of pairs of sensor elements, wherein each pair of sensor elements comprises two sensor elements oppositely arranged on the circumference of the circle; and a sensor circuit configured to generate a first pulse output signal based on a selected differential measurement signal indicative of a rotational speed of the object, wherein the sensor circuit is configured to generate a plurality of differential measurement signals using the plurality of sensor signals, one differential measurement signal for each pair of sensor elements of the plurality of pairs of sensor elements, wherein each differential measurement signal of the plurality of differential measurement signals is derived from the sensor signals generated by the corresponding pair of sensor elements, and wherein the sensor circuit is configured to select, as the selected differential measurement signal, the differential measurement signal of the plurality of differential measurement signals having the largest amplitude.

[0012] One or more embodiments provide a method of measuring rotation of a rotating object by a magnetic sensor, the magnetic sensor comprising a plurality of sensor elements arranged on a circumference of a circle in a sensor plane of the magnetic sensor and grouped into a plurality of pairs of sensor elements, wherein each pair of sensor elements comprises two sensor elements oppositely disposed on the circumference of the circle. The method comprises generating, in response to sensing an oscillating magnetic field modulated by the rotation of the rotating object, a plurality of sensor signals by the plurality of sensor elements, wherein each sensor signal is generated by one of the plurality of sensor elements; generating a first pulse output signal based on a selected differential measurement signal indicative of a rotational speed of the rotating object; generating a plurality of differential measurement signals using the plurality of sensor signals, one for each of the plurality of pairs of sensor elements, wherein each of the plurality of differential measurement signals is derived from the sensor signals generated by the corresponding pair of sensor elements; and selecting, from the plurality of differential measurement signals, a differential measurement signal having a largest magnitude as the selected differential measurement signal. BRIEF DESCRIPTION OF DRAWINGS

[0013] Embodiments are described herein with reference to the accompanying drawings.

[0014] Figure 1A and Figure 1B Plan views of two types of magnetic velocity sensors are shown in accordance with one or more embodiments;

[0015] Figure 2 A table providing an overview of twist direction and angle algorithms used by sensor circuitry in accordance with one or more embodiments is shown;

[0016] Figure 3 Various twist angle orientations of a magnetic velocity sensor are shown in accordance with one or more embodiments;

[0017] Figure 4 A cross-sectional view of a sensor system in accordance with one or more embodiments is shown;

[0018] Figure 5 A sensor module in accordance with one or more embodiments is shown;

[0019] Figure 6 A plan view of Figure 5 a sensor module is shown and magnetic field patterns coupled into a loop in an environment around the sensor module in accordance with one or more embodiments are shown; and

[0020] Figure 7 is a schematic block diagram of a sensor system comprising a magnetic velocity sensor in accordance with one or more embodiments. DETAILED DESCRIPTION

[0021] In the following, details are set forth in order to provide a thorough explanation of the exemplifying embodiments. It will be evident, however, to persons having ordinary skill in the art that the embodiments can be carried out without these specific details. In other instances, well-known structures and devices are shown in block diagram form or schematically without detailed details in order not to obscure the embodiments. Furthermore, the features of the different embodiments described hereinafter can be combined with each other, unless specifically stated otherwise. It is also to be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope defined by the claims. The following detailed description is, therefore, not to be taken in a limiting sense.

[0022] Furthermore, in the following description, like numbers refer to like elements throughout the description. It will be evident from the description below that implementations can be used without departing from the scope set forth in the claims. Certain features of the described implementations can also be used to good effect within the broader range of equivalents. The described features, structures, or characteristics can be combined in any suitable manner in one or more implementations. It will be apparent to those skilled in the art that the described implementations can be practiced without necessarily being limited to any particular programming language, operating system, or computer architecture.

[0023] Directional terms as used in this disclosure— such as "top," "bottom," "upper," "lower," "up," "down," "front," "back," "rear," "rearward," "forward," "front," "frontward," "aft," "aftward," and the like— can be used to describe the orientation of elements as they are depicted in the figures and / or as they are positioned in use. Because embodiments can be positioned in many different orientations, directional terms are used for illustrative purposes and are by no means limiting. In some instances, directional terms can be exchanged with equivalent directional terms based on the orientation of the embodiment, so long as the general directional relationship between elements and their general purpose is maintained.

[0024] In the present disclosure, expressions such as "first," "second," and the like can modify various elements. However, such elements are not limited by the aforesaid expressions. For example, the aforesaid expressions do not limit the sequence and / or importance of the elements. The aforesaid expressions are used only to distinguish an element from the other elements. For example, a first block and a second block represent different blocks although they are both blocks. As another example, a first element can be termed a second element, and similarly, a second element can also be termed a first element without departing from the scope of the present disclosure.

[0025] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0026] In the embodiments described herein or illustrated in the drawings, any direct electrical connection or coupling (i.e., any connection or coupling without additional intervening elements) can also be implemented by an indirect connection or coupling, i.e., a connection or coupling with one or more additional intervening elements, or vice versa, as long as the general purpose of the connection or coupling is substantially maintained, e.g., for transmitting a certain signal or transmitting a certain information. Features from different embodiments can be combined to form additional embodiments. For example, a change or modification described with respect to one of the embodiments can also be applicable to other embodiments, unless stated otherwise.

[0027] The term "substantially" can be used in the present document to account for small manufacturing tolerances that are considered acceptable in the industry (e.g., within 5%), without departing from aspects of the embodiments described herein.

[0028] Depending on certain implementation requirements, the storage media can include RAM, ROM, PROM, EPROM, EEPROM, or flash memory, or any other medium that is used to store electronic readable control signals which co-operate with (or are capable of co-operating with) a programmable computer system so as to perform a corresponding method. The storage medium can thus be considered as a computer-readable non-transitory storage medium.

[0029] Further, the instructions can be executed by one or more processors, such as one or more central processing units (CPU), digital signal processors (DSP), general purpose microprocessors, application specific integrated circuits (ASIC), field programmable logic arrays (FPGA), or other equivalent integrated or discrete logic circuitry. Accordingly, the term "processor," as used herein can refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein can be provided within dedicated hardware and / or software modules. Also, the techniques could be fully implemented in one or more circuits or logic elements. The "controller" that includes one or more processors can use electrical signals and digital algorithms to perform its receive, analyze, and control functions, which can also include correction functions.

[0030] As used herein, signal conditioning refers to manipulating an analog signal so that the signal meets the requirements for the next stage of further processing. Signal conditioning can include conversion from analog to digital (e.g., via an analog-to-digital converter), amplification, filtering, conversion, biasing, range matching, isolation, and any other processes needed to make the sensor output suitable for processing after conditioning.

[0031] Embodiments relate to sensors and sensor systems, and to acquiring information about sensors and sensor systems. A sensor can refer to a component that converts a physical quantity to be measured into an electrical signal (e.g., a current signal or a voltage signal). The physical quantity can include, for example, a magnetic field, an electric field, a pressure, a force, a current, or a voltage, but is not limited thereto. As described herein, a sensor device can be a speed sensor that measures a rotational speed of an object such as a gear.

[0032] For example, a magnetic field sensor includes one or more magnetic field sensor elements that measure one or more properties of a magnetic field (e.g., a quantity of magnetic flux density, a field strength, a field angle, a field direction, a field orientation, etc.). The magnetic field can be generated by a magnet, a current-carrying conductor (e.g., an electrical wire), the Earth, or other magnetic field sources. Each magnetic field sensor element is configured to generate a sensor signal (e.g., a voltage signal) in response to one or more magnetic fields impinging on the sensor element. Thus, the sensor signal is indicative of a magnitude and / or orientation of the magnetic field impinging on the sensor element.

[0033] Magnetic sensors include, for example, magnetoresistive sensors, inductive sensors, and Hall sensors. Magnetoresistance is a property of a material to change its resistance value when an external magnetic field is applied. Some examples of magnetoresistance effects are: giant magnetoresistance (GMR), which is a quantum mechanical magnetoresistance effect observed in thin-film structures composed of alternating ferromagnetic and non-magnetic conducting layers; tunneling magnetoresistance (TMR), which is an effect that occurs in a magnetoresistive magnetic tunnel junction (MTJ), which is a component composed of two ferromagnets separated by a thin insulator; or anisotropic magnetoresistance (AMR), which is a material property in which a dependence of resistance on an angle between a current direction and a magnetization direction can be observed. For example, in the case of an AMR sensor, the resistance of the AMR sensor element varies according to the square of the sine of the angle of the magnetic field component projected on the sensing axis of the ARM sensor element.

[0034] A plurality of different magnetoresistance effects are often abbreviated as xMR, where “x” acts as a placeholder for the various magnetoresistance effects. An xMR sensor can detect an orientation of an applied magnetic field by measuring the sine and cosine angular components using a monolithic integrated magnetoresistive sensor element.

[0035] The magnetoresistive sensor element of such an xMR sensor typically comprises a plurality of layers, wherein at least one layer is a reference layer having a reference magnetization, i.e. a reference direction. The reference magnetization provides a sensing direction corresponding to a sensing axis of the xMR sensor, such that the sensor element corresponds to a magnetic field component aligned with the sensing direction. For example, the magnetic field component can be an x magnetic field component (Bx), a y magnetic field component (By), or a z magnetic field component (Bz), wherein in the provided example, the Bx and By magnetic field components lie within the chip plane, and Bz lies out of the chip plane. Thus, if the magnetic field component points exactly in the same direction as the reference direction, the resistance of the xMR sensor element is maximum, whereas if the magnetic field component points exactly in the opposite direction to the reference direction, the resistance of the xMR sensor element is minimum.

[0036] In some applications, the xMR sensor comprises a plurality of magnetoresistive sensor elements having the same or different reference magnetization strengths. An example of such an application using various reference magnetizations is an angle sensor, a compass sensor, or a specific type of velocity sensor, e.g. a velocity sensor referred to as a bridge arrangement of single cells.

[0037] As an example, such a magnetoresistive sensor element is used in a velocity, angle, or rotational speed measurement device, wherein a magnet can be moved relative to the magnetoresistive sensor element and thus the magnetic field at the position of the magnetoresistive sensor element changes in case of movement, which in turn leads to a measurable change of the resistance. For the purpose of an angle sensor, the magnet or a magnet arrangement can be applied to a rotatable shaft, and the xMR sensor can be fixedly arranged relative thereto.

[0038] A Hall effect sensor is a transducer that changes its output voltage (Hall voltage) in response to a magnetic field. It is based on the Hall effect, which utilizes the Lorentz force. The Lorentz force deflects moving charges in the presence of a magnetic field perpendicular to the current flowing through the sensor or Hall plate. Thus, the Hall plate can be a thin piece of semiconductor or metal. The deflection causes a charge separation, which generates a Hall electric field. This electric field acts on the charges in the opposite direction of the Lorentz force. Both forces balance each other and produce a potential difference perpendicular to the current direction. The potential difference can be measured as the Hall voltage, and for small values, it varies linearly with the magnetic field. Hall effect sensors can be used for proximity switches, positioning, velocity detection, and current sensing applications.

[0039] A vertical Hall sensor is a magnetic field sensor constructed from a Hall element that is perpendicular to the plane of the sensor chip (e.g., extending from the main surface of the chip into the body of the chip). It senses the magnetic field perpendicular to its defined sensitive edge (top, right, or left with respect to the main surface of the chip). This typically means that the vertical Hall sensor is sensitive to magnetic field components that extend parallel to its surface and parallel to or in the plane of the main surface of the chip in which the vertical Hall sensor is integrated. In particular, the vertical Hall sensor can extend perpendicularly from the main surface into the chip (e.g., into the semiconductor substrate). The sensitivity plane can be referred to herein as a “sensitivity axis” or “sensing axis,” and each sensing axis has a reference direction. For a vertical Hall sensor element, the voltage value output by the sensor element varies as a function of the magnetic field strength in the direction of its sensing axis. For the purposes of this disclosure, the main surface of the sensor chip is defined in the XY plane, and the vertical Hall sensor is sensitive to fields in the XY plane (e.g., in the X direction, the Y direction, or a direction therebetween).

[0040] On the other hand, a lateral (planar) Hall sensor is constructed such that the Hall element is in the same plane as the main surface of the sensor chip. It senses the magnetic field perpendicular to its planar surface. This means that they are sensitive to magnetic fields that are perpendicular to or out of the plane of the main surface of the chip. The sensitivity plane can be referred to herein as a “sensitivity axis” or “sensing axis,” and each sensing axis has a reference direction. Similar to a vertical Hall sensor element, the voltage value output by the lateral Hall sensor element varies as a function of the magnetic field strength in the direction of its sensing axis. For the purposes of this disclosure, the main surface of the sensor chip is defined in the XY plane, and the lateral Hall sensor is sensitive to fields aligned along the Z direction perpendicular to the XY plane.

[0041] According to one or more embodiments, the plurality of magnetic field sensors and sensor circuitry can all be housed (i.e., integrated) in the same chip. The sensor circuitry can be referred to as signal processing circuitry and / or signal conditioning circuitry that receives one or more signals (i.e., sensor signals) from one or more magnetic field sensor elements in the form of raw measurement data and derives a measurement signal representative of the magnetic field from the sensor signals.

[0042] In some cases, the measurement signal can be a differential measurement signal that is derived from sensor signals generated by two sensor elements with the same sensing axis (e.g., two sensor elements that are sensitive to the same magnetic field component) using calculus. The differential measurement signal provides robustness to uniform external stray magnetic fields.

[0043] As used herein, signal conditioning refers to manipulating an analog signal such that the signal meets the requirements for the next stage of further processing. Signal conditioning can include conversion from analog to digital (e.g., via an analog-to-digital converter), amplification, filtering, conversion, biasing, range matching, isolation, and any other process needed to make the sensor output suitable for processing after conditioning.

[0044] Thus, the sensor circuit can include an analog-to-digital converter (ADC) that converts the analog signal from the one or more sensor elements to a digital signal. The sensor circuit can also include a DSP that performs some processing on the digital signal, which will be discussed below. Thus, a chip, which can also be referred to as an integrated circuit (IC), can include circuitry that conditions and amplifies the small signals of one or more magnetic field sensor elements via signal processing and / or conditioning.

[0045] As used herein, a sensor device can refer to a device that includes a sensor and a sensor circuit as described above. The sensor device can be integrated on a single semiconductor die (e.g., a silicon die or chip). Thus, the sensor and the sensor circuit are disposed on the same semiconductor die.

[0046] Figure 1A and Figure 1B Plan views of magnetic velocity sensors 100A and 100B, respectively, in accordance with one or more embodiments are shown. In particular, the magnetic velocity sensor 100A includes magnetic field sensor elements 1 that are sensitive to out-of-plane magnetic field components (i.e., magnetic fields aligned along the Z-direction perpendicular to the XY-plane of the sensor chip 10). In other words, the sensor elements 1 are transverse Hall sensor elements that are sensitive to Bz magnetic field components. In contrast, the magnetic velocity sensor 100B includes magnetic field sensor elements 11 that are sensitive to in-plane magnetic field components (e.g., magnetic fields aligned along the X-direction or Y-direction parallel to the XY-plane of the sensor chip 10). In other words, the sensor elements 11 are vertical Hall sensor elements or xMR sensor elements that are sensitive to in-plane magnetic field components, such as Bx or By magnetic field components.

[0047] Turning to Figure 1A The sensor elements 1 include sensor elements 1N, 1NE, 1E, 1SE, 1S, 1SW, 1W, and 1NW that are arranged equidistant from one another on a circle 12. The sensor elements 1N, 1NE, 1E, 1SE, 1S, 1SW, 1W, and 1NW are arranged equidistant from one another on a circumference of the circle 12. Thus, the sensor elements 1 are spatially uniformly distributed around a central axis 13 of the circle 12 such that all of the sensor elements 1 are exposed to substantially the same (due to typical assembly tolerances of 3%) or exactly the same magnetic field operating point. Here, the sensor elements 1N, 1NE, 1E, 1S, 1SE, 1SW, 1W, and 1NW are arranged 22.5° from one another.

[0048] The sensor elements 1 further include a central sensor element 1C arranged at the center of the circle 12, centered on, or proximate to, the central axis 13. When referring generally to the sensor elements of the magnetic velocity sensor 100A, the sensor elements 1N, 1NE, 1E, 1SE, 1S, 1SW, 1W, 1NW, and 1C can be collectively referred to as the sensor elements 1. The sensing axis of the sensor elements 1 is aligned in (parallel to) the z-direction for sensing the Bz magnetic field component.

[0049] The sensor elements 1N, 1NE, 1E, 1SE, 1S, 1SW, 1W, and 1NW are also grouped into different, mutually exclusive differential pairs that are arranged opposite each other across the circle 12 to form the differential pairs. Thus, four differential pairs are shown, including: a first pair of sensor elements 1N and 1S, a second pair of sensor elements 1E and 1W, a third pair of sensor elements 1NE and 1SW, and a fourth pair of sensor elements 1NW and 1SE. The more differential pairs that are provided, the better the performance of the sensor. For example, more differential pairs represent higher resolution and better accuracy of velocity sensing and rotational direction detection, which will be discussed in more detail below.

[0050] While four differential pairs are shown, only two pairs need to be arranged perpendicular to each other. For example, the two pairs can include the first pair and the second pair because a line extending through the central axis 13 and the first pair is perpendicular to a line extending through the central axis 13 and the second pair. Likewise, the two pairs can include the third pair and the fourth pair because a line extending through the central axis 13 and the third pair is perpendicular to a line extending through the central axis 13 and the fourth pair. Additional differential pairs can be added to the minimum two pairs to enhance the performance of the sensor.

[0051] The sensor chip 10 can be a semiconductor substrate that further includes additional circuitry for processing the sensor signals generated by the sensor elements 1. The magnetic velocity sensor 100A further includes power supply pins V+ and GND 10 and components thereof that supply power to the sensor chip.

[0052] The sensor signal of each sensor element 1 is provided to a sensor circuit 20 (not shown) that generates or calculates a velocity measurement signal for each differential pair using differential calculations that cancel out uniform stray fields. Thus, each velocity measurement signal is a differential signal calculated from two sensor signals. For example, the following velocity measurement signals can be calculated based on the sensor signals output by each sensor element 1:

[0053] V speed1 = V 1W -V 1E (1),

[0054] V speed2= V 1N -V 1S (2),

[0055] V speed3 = V 1SW -V 1NE (3), and

[0056] V speed4 = V 1NW -V 1SE (4).

[0057] Each voltage value V 1N , V 1NE , V 1E , V 1SE , V 1S , V 1SW , V 1W and V 1NW represents a sensor signal from the respective sensor element 1N, 1NE, 1E, 1SE, 1S, 1SW, 1W and 1NW. If an xMR sensor is used, the sensor signals can be represented in a similar manner as resistance values.

[0058] The sensor circuit 20 is further configured to analyze the amplitude of each speed measurement signal (V speed1 , V speed2 , V speed3 and V speed4 ) in real time and to determine which speed measurement signal has the largest amplitude (or magnitude, irrespective of the sign). At any given moment, the sensor circuit 20 selects the speed measurement signal with the largest amplitude to be used as the selected speed measurement signal for generating the output signal. The other, non-selected speed measurement signals are not used for generating the output signal and, in this sense, are ignored by the sensor circuit 20.

[0059] Any time one speed measurement signal becomes the signal with the largest amplitude, this speed measurement signal is selected for the output. This means that the sensor circuit 20 continuously monitors the amplitude of each speed measurement signal by comparing each speed measurement signal to each other and can dynamically switch between speed measurement signals when a speed measurement signal becomes the signal with the largest amplitude. If the amplitudes of two speed measurement signals are equal, the sensor circuit 20 selects one of the two speed measurement signals. The sensor circuit 20 can use multiple channels and a multiplexer to selectively output the selected speed measurement signal.

[0060] The amplitude of each of the velocity measurement signals can change based on the twist orientation and in particular based on the twist rotation of the sensor 100A about the central axis 13 relative to a reference direction or reference axis. For example, the tangent line of the target wheel at the point of tangency can be parallel to one axis of the sensor plane (e.g., the x-axis). The point of tangency is the point between the sensor chip 10 and the target wheel that has the smallest distance (smallest air gap). Along this reference axis, the sensed magnetic field in the sensing direction will have the largest peak-to-peak variation and thus the largest amplitude as the target wheel rotates. Thus, the differential pair that is most closely aligned along the reference axis will provide the best velocity measurement signal to use for generating the output signal.

[0061] The velocity measurement signals represent the rotational speed of the target object, such as a gear or pole wheel made of alternating north and south poles. The central sensor element 1C can also generate a sensor signal Sdir that serves as a direction signal. The direction signal relative to the velocity measurement signals represents the rotational direction (e.g., clockwise or counterclockwise rotation) of the motion of the target object. In particular, the direction signal has a phase shift relative to the velocity measurement signals, and the sign of the phase shift (i.e., positive phase shift or negative phase shift) indicates the rotational direction of the target object.

[0062] In particular, the phase shift can be positive or negative 90 degrees, but is not necessarily limited thereto. The direction signal can be a phase-shifted copy of the velocity measurement signal with the same oscillation frequency, although it is smaller in amplitude because it is generated by a single-cell sensor element. Thus, it is conceivable that through amplification and signal processing, the velocity signal can be used as the direction signal and vice versa.

[0063] The sensor circuit 20 can be configured to evaluate the phase shift between the selected velocity measurement signal and the corresponding direction signal each time the selected velocity measurement signal crosses one or more switching thresholds on a rising transition, a falling transition, or both. The crossing of the switching threshold is considered a sampling time that triggers the evaluation. In other words, the evaluation is performed periodically to determine the rotational direction of the target object.

[0064] Alternatively, the sensor circuit 20 can use a Coordinate Rotational Digital Computer (CORDIC) algorithm on the differential signals from the two orthogonal differential pairs to determine the rotational direction of the target wheel. One of the two orthogonal differential pairs corresponding to the selected velocity measurement signal will be selected by the sensor circuit 20, and the other differential pair will be the pair that is orthogonal thereto.

[0065] Thus, the sensor circuit 20 can evaluate the selected velocity measurement signal as well as the direction signal generated by the sensor element 1C to determine the rotational direction of the target object.

[0066] Depending on which speed measurement signal is determined to be the signal with the largest amplitude, the sensor circuit 20 can also determine the torsional orientation of the sensor 100A around the central axis 13 and in particular its torsional rotation. This rotation value in degrees can also be referred to as the torsional rotation of the sensor 100A.

[0067] For example, the sensor circuit 20 can also use the speed measurement signal determined to be the largest amplitude signal (i.e., the selected speed measurement signal) to determine the torsional rotation of the sensor 100A relative to a zero degree reference position. For example, each differential pair of sensor elements can have a position mapped to a corresponding torsional rotation angle. The differential pair that generates the differential signal (speed measurement signal) of the largest amplitude is most closely aligned (if not perfectly aligned) with the reference axis (e.g., the x-axis) and indicates the torsional rotation angle of the sensor 100B. If the two speed measurement signal amplitudes are equal, the sensor circuit 20 can also determine the torsional rotation angle based on which two speed measurement signal amplitudes and their signs (positive or negative) are equal.

[0068] For example, Figure 2 A table is shown that provides an overview of the torsional direction and angle algorithm used by the sensor circuit 20 according to one or more embodiments. In Figure 2 In the table shown, the grayed out cells refer to the cells for the “primary” differential pair (i.e., the pair of sensing elements with the largest amplitude). For the case where there are two primary differential pairs (i.e., pairs of sensing elements with the same largest amplitude), the torsional angle assignment is also shown. The torsional direction is also designated as a positive torsional direction is designated for torsional angles from 270 to 90 degrees and a negative torsional direction is designated for torsional angles from 90 to 270 degrees.

[0069] Furthermore, the particular values of the speed measurement signals of the largest amplitude can map to analog or discrete torsional angle values. Thus, each speed measurement signal can cover a range of torsional angle values that the sensor circuit 20 can discern.

[0070] By determining the torsional angle, the sensor 100A can be used as an angle sensor.

[0071] Turning back Figure 1BThe sensor elements 11 comprise sensor elements 11N, 11NE, 11E, 11SE, 11S, 11SW, 11W, and 11NW, which are arranged equidistant to each other on the circle 12. The sensor elements 11N, 11NE, 11E, 11SE, 11S, 11SW, 11W, and 11NW are arranged equidistant to each other on the circumference of the circle 12. Thus, the sensor elements 11 are spatially uniformly distributed around the central axis 13 of the circle 12, such that all sensor elements 11 are exposed to essentially the same (due to typical assembly tolerances of 3%) or exactly the same magnetic field working point. Here, the sensor elements 11N, 11NE, 11E, 11S, 11SE, 11SW, 11W, and 11NW are arranged 22.5° to each other.

[0072] The sensor elements 11 further comprise sensor elements 11Cx and 11Cy, which are arranged in or close to the center of the circle 12. When generally referring to the sensor elements of the magnetic speed sensor 100B, the sensor elements 11N, 11NE, 11E, 11SE, 11S, 11SW, 11W, 11NW, 11Cx, and 11Cy can be collectively referred to as sensor elements 11.

[0073] The sensor elements 11 each have a sensing axis for the speed sensor, which is aligned with one of the in-plane magnetic field components Bx or By. The arrow on each sensor element 11 indicates the sensing direction of the sensor element 11. The sensing direction of the sensor elements 11N, 11S, 11NE, 11SW, and 11Cy is the same. The sensing direction of the sensor elements 11E, 11W, 11NW, 11SE, and 11Cx is the same. In particular, according to this example, the oppositely arranged sensor elements 11E and 11W can have a sensing axis along the x-direction, which is configured to sense the in-plane magnetic field component Bx (i.e., to be sensitive to the magnetic field in the x-plane). Similarly, the oppositely arranged sensor elements 11N and 11S can have a sensing axis along the y-direction, which is configured to sense the in-plane magnetic field component By (i.e., to be sensitive to the magnetic field in the y-plane).

[0074] If the sensor elements 11 are xMR sensors, each sensor element 11 has a reference layer, the reference direction of which defines its sensing axis (i.e., its sensing direction). Thus, if the magnetic field points in exactly the same direction as the reference direction, the resistance of the xMR sensor element is maximum, whereas if the magnetic field points in exactly the opposite direction to the reference direction, the resistance of the xMR sensor element is minimum.

[0075] The sensor elements 11N, 11NE, 11E, 11SE, 11S, 11SW, 11W, and 11NW are also grouped into different mutually exclusive differential pairs, which are disposed opposite each other across the circle 12 to form differential pairs. Thus, four differential pairs are shown, including: a first pair of sensor elements 11N and 11S, a second pair of sensor elements 11E and 11W, a third pair of sensor elements 11NE and 11SW, and a fourth pair of sensor elements 11NW and 11SE. The more differential pairs that are provided, the better the performance of the sensor. For example, more differential pairs mean higher resolution and better accuracy of rotational direction detection, which will be discussed in more detail below.

[0076] While four differential pairs are shown, only two pairs are needed. The two pairs can be arranged perpendicular to each other. For example, the two pairs can include the first pair and the second pair because a line extending through the central axis 13 and the first pair is perpendicular to a line extending through the central axis 13 and the second pair. Likewise, the two pairs can include the third pair and the fourth pair because a line extending through the central axis 13 and the third pair is perpendicular to a line extending through the central axis 13 and the fourth pair.

[0077] The sensor signals of each sensor element 11 are provided to a sensor circuit 20 (not shown) that generates or calculates a velocity measurement signal for each differential pair using differential calculations that cancel out uniform stray fields in the x and y directions, and out-of-plane magnetic field components do not affect the output signal (i.e., the sensor output). Thus, each velocity measurement signal is a differential signal calculated from two sensor signals. For example, the following velocity measurement signals can be calculated based on the xMR sensor signals output by each sensor element 11:

[0078] R speed1 = R 11W R 11E (5),

[0079] R speed2 = R 11N R 11S (6),

[0080] R speed3 = R 11SW R 11NE (7), and

[0081] R speed4 = R 11NW R 11SE (8).

[0082] Each resistance value R 11N , R 11NE , R 11E , R 11SE , R 11S , R11SW , R 11W , and R 11NW represent the sensor signals from the respective sensor elements 11N, 11NE, 11E, 11SE, 11S, 11SW, 11W, and 11NW. Alternatively, each differential pair can be arranged in a separate bridge circuit together with two known resistors. The output of each bridge circuit is a differential voltage value which can be used as the respective speed measurement signal V speed1 , V speed2 , V speed3 , or V speed4 .

[0083] If Hall sensor elements are used as sensor elements 11, equations 1-4 can be used to calculate the speed measurement signals.

[0084] The sensor circuit 20 is further configured to analyze the amplitude of each speed measurement signal (R speed1 , R speed2 , R speed3 , and R speed4 , or V speed1 , V speed2 , V speed3 , and V speed4 ) in real time and determine which speed measurement signal has the largest amplitude (or magnitude, regardless of sign). At any given moment, the sensor circuit 20 selects the speed measurement signal with the largest amplitude to use as the selected speed measurement signal for generating the output signal. The other, non-selected speed measurement signals are not used to generate the output signal and, in this sense, are ignored by the sensor circuit 20.

[0085] Any time one of the speed measurement signals becomes the signal with the largest amplitude, that speed measurement signal is selected for output. This means that the sensor circuit 20 continuously monitors the amplitude of each speed measurement signal by comparing each speed measurement signal to each other and can dynamically switch between speed measurement signals when a speed measurement signal becomes the signal with the largest amplitude. If the amplitudes of two speed measurement signals are equal, the sensor circuit 20 selects one of the two speed measurement signals. The sensor circuit 20 can use multiple channels and a multiplexer to selectively output the selected speed measurement signal.

[0086] The amplitude of each of the velocity measurement signals can change based on the twist orientation and in particular based on the twist rotation of the sensor 100B around the central axis 13 relative to a reference direction or reference axis. For example, the tangent of the target wheel at the point of tangency can be parallel to one axis of the sensor plane (e.g., the x-axis). The point of tangency is the point between the sensor chip 10 and the target wheel that has the smallest distance (smallest air gap). Along this reference axis, the sensed magnetic field in the sensing direction will have the largest peak-to-peak variation and thus the largest amplitude as the target wheel rotates. Thus, the differential pair that is most closely aligned along the reference axis will provide the best velocity measurement signal to be used to generate the output signal.

[0087] The velocity measurement signals represent the rotational speed of the target object, such as a gear or pole wheel made of alternating north and south poles. The central sensor elements 11Cx and 11Cy can also generate a sensor signal Sdir that serves as a direction signal. The direction signal relative to the velocity measurement signals represents the rotational direction (e.g., clockwise or counterclockwise rotation) of the motion of the target object. The direction signal has a phase shift relative to the velocity measurement signals, and the sign of the phase shift (i.e., positive phase shift or negative phase shift) indicates the rotational direction of the target object.

[0088] In particular, the phase shift can be positive or negative 90 degrees, but is not necessarily limited thereto. The direction signal can be a phase-shifted copy of the velocity measurement signal, albeit with a smaller amplitude, as it is generated by a single cell sensor element. As such, the direction signal Sdir is selected from the sensor outputs of the central sensor elements 11Cx and 11Cy based on which differential pair is selected for the output of the velocity measurement signal. If the differential pair that senses the Bx magnetic field component is selected as the signal with the largest amplitude, then the output of the central sensor element 11Cx is selected by the sensor circuit 20 as the useful direction signal. By contrast, if the differential pair that senses the By magnetic field component is selected as the signal with the largest amplitude, then the output of the central sensor element 11Cy is selected by the sensor circuit 20 as the useful direction signal. This ensures that the direction signal is a phase-shifted copy of the selected velocity measurement signal.

[0089] The sensor circuit 20 can evaluate the selected velocity measurement signal together with the selected direction signal to determine the rotational direction of the target object, as similarly described above.

[0090] Depending on which velocity measurement signal is determined to be the signal with the largest amplitude, the sensor circuit 20 can also determine the twist orientation of the sensor 100A around the central axis 13 and in particular its twist rotation. This rotation value in degrees can also be referred to as the twist rotation of the sensor 100B.

[0091] For example, the sensor circuit 20 also uses the speed measurement signal determined to be the maximum amplitude signal (i.e., the selected speed measurement signal) to determine the twist rotation of the sensor 100B relative to the zero-degree reference position. For example, each differential pair of sensor elements can have a position mapped to a corresponding twist rotation angle. The differential pair that generates the maximum amplitude differential signal (speed measurement signal) is most closely aligned (if not perfectly aligned) with the reference axis (e.g., the x-axis) and indicates the twist rotation angle of the sensor 100B. If two speed measurement signal amplitudes are equal, the sensor circuit 20 can also determine the twist rotation angle based on which two speed measurement signal amplitudes and their signs (positive or negative) are equal.

[0092] For example, Figure 2 A table providing a summary of the twist direction and angle algorithm is shown. In Figure 2 In the table shown, the grayed-out cells are cells referring to the “primary” differential pair (i.e., the pair of sense elements with the largest amplitude). Twist angle assignments are also shown for the case where there are two primary differential pairs (i.e., pairs of sense elements with the same maximum amplitude). Twist direction is also designated as positive twist direction is designated for twist angles from 270 to 90 degrees and negative twist direction is designated for twist angles from 90 to 270 degrees.

[0093] Furthermore, specific values of the speed measurement signal of maximum amplitude can map to analog or discrete twist angle values. Thus, each speed measurement signal can cover a range of twist angle values that the sensor circuit 20 can discern.

[0094] By determining the twist angle, the sensor 100B can be used as an angle sensor.

[0095] Figure 3 Various twist angle orientations of the magnetic speed sensor 100A are shown in accordance with one or more embodiments. Similar twist angle orientations and results apply equally to the magnetic speed sensor 100B. Here, the x-axis is the reference axis (direction), and the magnetic speed sensor at 0° corresponds to the reference position. For simplicity, only the primary sensor element pairs are labeled. A differential pair is primary when it is aligned (or closest aligned) with the reference axis.

[0096] When the sensor elements 1E and 1W are the primary differential pair (i.e., the pair of sense elements with the largest amplitude) and their speed measurement signals are positive, the twist angle is determined to be 0°. In contrast, when the sensor elements 1E and 1W are the primary differential pair (i.e., the pair of sense elements with the largest amplitude) and their speed measurement signals are negative, the twist angle is determined to be 180°.

[0097] When sensor elements 1NE and 1SW are the primary differential pair (i.e., the sensing element pair with the largest amplitude) and their velocity measurement signals are positive, the torsion angle is determined to be 45°. In contrast, when sensor elements 1NE and 1SW are the primary differential pair (i.e., the sensing element pair with the largest amplitude) and their velocity measurement signals are negative, the torsion angle is determined to be 225°.

[0098] When sensor elements 1N and 1S are the primary differential pair (i.e., the sensing element pair with the largest amplitude) and their velocity measurement signals are negative, the torsion angle is determined to be 90°. In contrast, when sensor elements 1N and 1S are the primary differential pair (i.e., the sensing element pair with the largest amplitude) and their velocity measurement signals are positive, the torsion angle is determined to be 270°.

[0099] When sensor elements 1NW and 1SE are the primary differential pair (i.e., the sensing element pair with the largest amplitude) and their velocity measurement signals are negative, the torsion angle is determined to be 135°. In contrast, when sensor elements 1NW and 1SE are the primary differential pair (i.e., the sensing element pair with the largest amplitude) and their velocity measurement signals are positive, the torsion angle is determined to be 315°.

[0100] Additional torsion angle can be obtained from Figure 2 Collected in the table shown.

[0101] Figure 4 A cross-sectional view of a sensor system 200 according to one or more embodiments is shown. Specifically, Figure 4 A sensor system 200 is shown, comprising a magnetized encoder wheel (i.e., a magnetic pole wheel) 61, which serves as a target object consisting of alternating north pole portions 62 and south pole portions 63. The target object could also be a gear. Thus, the north pole portion 62 and the south pole portion 63 represent the teeth and grooves of a gear. Here, a magnetic velocity sensor 100B is shown as a sensor chip 10 located on a back-biased magnet 15 and having an air gap with the wheel 61. The back-biased magnet 14 is an axially polarized back-biased magnet, such as a cylinder or a pellet, which generates a radially symmetrical bias magnetic field in the sensor plane, wherein the radially symmetrical bias magnetic field is zero at the central axis 13 of the axially polarized back-biased magnet and increases radially from the central axis 13 in the sensor plane.

[0102] Sensor element 11 is sensitive to the radial magnetic field of back-biased magnet 15, which is influenced by the north pole portion 62 and south pole portion 63 of wheel 61. Furthermore, sensor circuit 20 of magnetovelocity sensor 100B is shown. Sensor circuit 20 generates a sensor output corresponding to the rotational speed and direction of rotation of wheel 61 by detecting changes in the alternating magnetic field. Sensor circuit 20 can also output a torsion angle signal representing the torsion angle of sensor chip 10 relative to a reference axis or reference direction.

[0103] The sensor circuit 20 can transmit the sensor output signal to an external processor or controller unit, such as an ECU for speed computation and determination, which in turn can provide the speed measurement to a user or other processing or output components, such as a display.

[0104] Figure 5 A sensor module 70 according to one or more embodiments is shown. In particular, Figure 5 A magnetic speed sensor 100A is shown, which includes a transverse Hall sensor element 1 and a magnetic back-bias circuit 74 enabling torsion-insensitive and stray field robust sensing of a target wheel (e.g., a gear wheel or a magnetized encoder wheel).

[0105] The sensor module 70 includes a sensor chip 71 having a leadframe 72 extending therefrom, a back-bias magnet 74 located at the backside of the sensor chip 10 and magnetized in the (in-plane) x-direction, a first magnetic flux guide 76a, and a second magnetic flux guide 76b.

[0106] The sensor chip 10 includes sensor elements (e.g., Hall plates) IN, INE, IE, ISE, IS, ISW, IW, INW, and IC, whose sensitivity axes are aligned parallel to the z-axis, which is an out-of-plane component of the sensor chip 10 and is sensitive to the magnetic field component Bz (i.e., the magnetic field in the z-plane). Here, the backside of the sensor chip 10 refers to the side farthest from the target wheel, and the frontside of the sensor chip 10 faces the target wheel in the z-direction.

[0107] The back-bias magnet 74 is magnetized in the x-direction parallel to the in-plane component of the sensor chip 71. The back-bias magnet 74 can be, for example, a bulk or cylindrical magnet placed between the first and second magnetic flux guides 76a, 76b and coupled to the backside of the sensor chip 71.

[0108] The first and second magnetic flux guides 76a, 76b are located at opposite magnetic poles of the magnet 74 and are made of a material (e.g., iron) capable of redirecting the magnetic field generated by the magnet 74. In particular, Figure 6A plan view of the sensor module 70 is shown, showing the magnetic field pattern coupled in a loop 77 in the environment around the sensor module 70. With the magnet 74 magnetized in the x-direction, the B magnetic field (flux lines) starts in the x-direction at point 77a, a portion of the B magnetic field is redirected by the second flux guide 76b at points 77b and 77c, such that the B magnetic field is guided through the (in-plane) x-plane of the sensor package 71 at point 77d anti-parallel to the x-direction, and a portion of the B magnetic field is redirected again by the first flux guide 76a at points 77e and 77f, such that the B magnetic field is again pointing in the x-direction.

[0109] Without the ferrous target wheel (or before the notch), the B magnetic field will exit the second flux guide 76b and couple again directly into the first flux guide 76a. Thus, there is a strong negative Bx field and almost no Bz or By field at the sensor location (i.e., at the sensor element 1). Thus, the Bz sensitive Hall plates are exposed to a low Bz field and the offset is small.

[0110] In contrast, with the wheel present (or in front of the teeth), the magnetic field will be pulled towards the target wheel in the z-direction. For example, the Bz field on the sensor element 1W and the sensor element 1E increases in opposite signs due to the increase in Bz field strength.

[0111] Figure 7 is a schematic block diagram of a sensor system 300 comprising a magnetic velocity sensor according to one or more embodiments. The sensor system 300 comprises a magnetic velocity sensor 100A or 100B, which is represented by a sensor chip 10.

[0112] The sensor chip 10 is configured to generate at least two output signals OUT1 and OUT2, a third output signal OUT3 being optional. A microcontroller 30 is configured to receive the output signals OUT1, OUT2 and OUT3 for additional analysis and / or processing.

[0113] The first output signal OUT1 can be a selected velocity measurement signal, and the second output signal OUT2 can be a direction signal or a signal representative thereof. Further, the third output signal OUT3 can be a twist angle signal providing a twist angle of the sensor chip 10 based on a twist orientation of the sensor chip 10.

[0114] The magnetic chip 10 comprises a sensor element 1 or 11, as described in Figure 1A and Figure 1B The sensor element senses a change in magnetic field strength, which changes (oscillates) with a sinusoidal waveform modulated by a rotating target object (i.e., with signal modulation). The sinusoidal waveform has a frequency corresponding to a rotational speed of the rotating target object, such as a wheel or a drive shaft.

[0115] The sensor chip 10 comprises a sensor circuit 20, which comprises a sensor processing circuit 21 configured to receive analog sensor signals from the sensor elements and perform signal processing and / or conditioning thereon. The analog sensor signals can be received individually from each sensor element, or can be generated from each differential pair as a velocity measurement signal and a direction signal. If the sensor elements 1, 11 are coupled in a differential configuration, such as a bridge circuit, the sensor processing circuit 21 comprises corresponding differential circuitry. If the analog sensor signals are from individual sensor elements, the sensor processing circuit 21 can also generate a velocity measurement signal by applying calculus thereto. The sensor processing circuit 21 can also comprise an analog-to-digital converter (ADC) to convert the analog sensor signals to digital sensor signals.

[0116] The processed sensor signals are output from the sensor processing circuit 21 and provided to a velocity and direction processing circuit 22. In this example, the velocity and direction processing circuit 22 receives a velocity measurement signal from each differential pair of sensor elements, and any direction signal from the central sensor element. The velocity and direction processing circuit 22 evaluates the magnitude of each velocity measurement signal (e.g., via a comparison), determines which velocity measurement signal is the largest magnitude signal, and selects the largest magnitude velocity measurement signal to use as a useful velocity signal. In the case of the magnetic velocity sensor 100B, the velocity and direction processing circuit 22 also selects one of the sensor signals from sensor elements 11Cx and 11Cy as a useful direction signal. The useful direction signal is a measurement of the same magnetic field component (e.g., Bx or By) as the selected velocity measurement signal. If the sensor signals have not already been converted to digital, the velocity and direction processing circuit 22 can comprise an ADC to convert the selected (useful) signals to digital signals.

[0117] The velocity and direction processing circuit 22 can also determine a twist angle of the sensor chip 10 based on the above-described algorithm.

[0118] The output generator 23 analyzes the selected speed measurement signal and the corresponding direction signal and generates pulsed output signals OUT1 and OUT2. Specifically, the output generator 23 can include a current modulator, also known as a protocol generator, that receives the selected speed measurement signal and the corresponding direction signal and generates the pulsed output signals OUT1 and OUT2 as output currents according to, for example, a programmed current switching protocol or rule set constructed by the comparator. The output currents can be between two current values to generate current pulses. The current pulses are triggered when the selected speed measurement signal crosses one or more switching thresholds on a rising transition, a falling transition, or both, the frequency of the current pulses being directly related to the speed of the target object. The pulsed output signal OUT2 has the same frequency as the pulsed output signal OUT1. However, the pulses of the pulsed output signal OUT2 are either in phase (i.e., have a zero phase shift) or completely out of phase (i.e., have a 180° phase shift) with the pulses of the pulsed output signal OUT1 depending on the direction of movement (e.g., rotation) of the target object. For example, for a rotating target object, the pulse edges of the OUT1 and OUT2 signals can be aligned and in phase with each other in the case of the target object rotating in a first direction (e.g., counterclockwise). In contrast, the pulse edges of the OUT1 and OUT2 signals can be aligned and out of phase with each other in the case of the target object rotating in a second direction (e.g., clockwise). The output generator 23 can determine the direction based on whether the 90° phase shift between the selected speed measurement signal and the direction signal is positive or negative.

[0119] The output generator 23 can also receive and output a twist angle as an output signal OUT3 (analog or digital).

[0120] Accordingly, the above-described embodiments provide for twist insensitive mounting of the differential sensors 100A and 100B with rotation direction detection and optional twist angle determination.

[0121] While the above-described embodiments are described in the context of detecting wheel or camshaft speed, the sensors can be used to detect the rotational speed of any rotating member or object that produces sinusoidal changes in a magnetic field as it rotates and can be sensed by the sensor, including crankshaft and transmission speed sensing. For example, a combination of a ferrous wheel and back biased magnets can be used to generate a time varying magnetic field.

[0122] Furthermore, while various embodiments have been described herein, it should be apparent that many modifications are possible in the structures set forth herein without materially departing from the scope of the application. Therefore, the scope of the application is indicated by the appended claims, along with the full scope of equivalents to which such claims are entitled. With respect to the various functions described above, it is to be understood that the term means for should not be construed to cover structures merely responsible for enabling functionality, and that such structures do not inherently produce that functionality. Rather, structures described as means for are structures that have the specific, explicit, and assignable function indicated, and any structure that causes an effect that is the same as that explicitly described will qualify as the means for.

[0123] Furthermore, the following claims are hereby incorporated into the detailed description, wherein each claim can stand on its own as a separate example embodiment. While each claim can stand on its own as a separate example embodiment, it is to be noted that though a dependent claim can refer in the claims to a specific combination with one or more other claims, other example embodiments can include the subject matter of the dependent claim in combination with each other dependent or independent claim. Such combinations are hereby presented, unless it is explicitly stated that a specific combination should not be used. In addition, it is intended that features of a claim be included in any other independent claim, even if this is not explicitly stated in the claim.

[0124] It should also be noted that a method disclosed in the specification or claims can be implemented by a device having means for performing each of the respective actions of the method.

[0125] Furthermore, it should be understood that the disclosure of a multiple-numbered act or function as a claim limitation does not, unless otherwise indicated, limit the number of acts or functions to the specified number. The disclosure of "more than one" or "plurality" should not be interpreted as "two or more". It is possible for a single act or function to fulfill the requirements of more than one claim limitation. Furthermore, the disclosure of multiple acts or functions connected by "or" should not be interpreted as being limited to alternative arrangements— one of the acts or functions being performed exclusively when another is not being performed.

Claims

1. A magnetic sensor configured to detect a rotation of an object, comprising: a plurality of sensor elements arranged in a sensor plane of the magnetic sensor, wherein the plurality of sensor elements is configured to generate a plurality of sensor signals in response to sensing an oscillating magnetic field modulated by the rotation of the object, wherein each sensor signal is generated by one of the plurality of sensor elements, wherein the plurality of sensor elements is arranged on a circumference of a circle, wherein the plurality of sensor elements is grouped into a plurality of pairs of sensor elements, wherein each pair of sensor elements comprises two sensor elements oppositely arranged on the circumference of the circle; and a sensor circuit configured to generate a first pulsed output signal based on a selected differential measurement signal indicative of a rotational speed of the object, wherein the sensor circuit is configured to generate a plurality of differential measurement signals using the plurality of sensor signals, each of the plurality of pairs of sensor elements corresponding to one of the differential measurement signals, wherein each of the plurality of differential measurement signals is derived from the sensor signals generated by the corresponding pair of sensor elements, and wherein the sensor circuit is configured to select, from the plurality of differential measurement signals, the differential measurement signal having a largest amplitude as the selected differential measurement signal.

2. The magnetic sensor of claim 1, wherein the sensor circuit is configured to continuously monitor the amplitudes of each of the plurality of differential measurement signals by comparing the amplitudes to each other and dynamically selecting the differential measurement signal having the largest amplitude from the plurality of differential measurement signals as the selected differential measurement signal.

3. The magnetic sensor of claim 1, wherein the plurality of sensor elements is arranged on the circumference of the circle at equidistant angles around a center of the circle.

4. The magnetic sensor of claim 1, wherein the sensor circuit is configured to generate an output signal disregarding a remainder of the differential measurement signals not selected as the selected differential measurement signal.

5. The magnetic sensor of claim 1, further comprising: a central sensor element arranged in a central region of the circle in the sensor plane, the central sensor element configured to generate a central sensor signal in response to sensing the oscillating magnetic field, wherein the sensor circuit is configured to generate a phase-shift measurement signal using the central sensor signal and a second pulsed output signal based further on the phase-shift measurement signal and the selected differential measurement signal.

6. The magnetic sensor of claim 5, wherein a phase of the second pulsed output signal relative to a phase of the first pulsed output signal is indicative of a rotational direction of the object.

7. The magnetic sensor of claim 1, wherein the plurality of sensor elements has a sensing axis extending orthogonally to the sensor plane and is sensitive to an out-of-plane magnetic field component of the oscillating magnetic field.

8. The magnetic sensor of claim 1, wherein the plurality of pairs of sensor elements comprises: at least one first pair of sensor elements sensitive to a first in-plane magnetic field component of the oscillating magnetic field aligned along a first in-plane direction of the sensor plane, and at least one second pair of sensor elements sensitive to a second in-plane magnetic field component of the oscillating magnetic field aligned along a second in-plane direction of the sensor plane.

9. The magnetic sensor of claim 8, wherein the first in-plane direction is orthogonal to the second in-plane direction.

10. The magnetic sensor of claim 8, further comprising: a first central sensor element arranged in a central region of the circle in the sensor plane and sensitive to the first in-plane magnetic field component of the oscillating magnetic field, wherein the first central sensor element is configured to generate a first central sensor signal in response to sensing the first in-plane magnetic field component of the oscillating magnetic field; and a second central sensor element arranged in the central region of the circle in the sensor plane and sensitive to the second in-plane magnetic field component of the oscillating magnetic field, wherein the second central sensor element is configured to generate a second central sensor signal in response to sensing the second in-plane magnetic field component of the oscillating magnetic field, wherein the sensor circuitry is configured to select the first central sensor signal or the second central sensor signal to use as a phase-shift measurement signal based on the selected differential measurement signal, and to generate a second pulsed output signal further based on the phase-shift measurement signal and the selected differential measurement signal.

11. The magnetic sensor of claim 10, wherein a phase of the second pulsed output signal relative to a phase of the first pulsed output signal is indicative of a direction of rotation of the object.

12. The magnetic sensor of claim 1, wherein the circle has a central axis about which the magnetic sensor is twisted to reach different twisted orientations having different twist angles relative to a reference direction.

13. The magnetic sensor of claim 12, wherein the sensor circuitry is configured to determine a twist angle of the magnetic sensor relative to the reference direction based on the selected differential measurement signal.

14. The magnetic sensor of claim 13, wherein the sensor circuitry is configured to generate a twist angle output signal representing the determined twist angle.

15. The magnetic sensor of claim 12, wherein the amplitude of each of the plurality of differential measurement signals changes based on the twist angle of the magnetic sensor.

16. A method of measuring rotation of a rotating object by a magnetic sensor, the magnetic sensor comprising a plurality of sensor elements arranged on a circumference of a circle in a sensor plane of the magnetic sensor and grouped into a plurality of pairs of sensor elements, wherein each pair of sensor elements comprises two sensor elements oppositely disposed on the circumference of the circle, the method comprising: generating, by the plurality of sensor elements, a plurality of sensor signals in response to sensing an oscillating magnetic field modulated by the rotation of the rotating object, wherein each sensor signal is generated by one of the plurality of sensor elements; ​ generating a first pulsed output signal based on a selected differential measurement signal indicative of a rotational speed of the rotating object; generating a plurality of differential measurement signals using the plurality of sensor signals, each pair of the plurality of pairs of sensor elements corresponding to one differential measurement signal, wherein each differential measurement signal of the plurality of differential measurement signals is derived from sensor signals generated by the corresponding pair of sensor elements; and selecting, from the plurality of differential measurement signals, a differential measurement signal having a largest amplitude as the selected differential measurement signal.

17. The method of claim 16, further comprising: continuously monitoring the amplitudes by comparing the amplitudes of each of the plurality of differential measurement signals to each other; and dynamically selecting, from the plurality of differential measurement signals, the differential measurement signal having the largest amplitude as the selected differential measurement signal as the amplitudes change.

18. The method of claim 16, further comprising: in response to sensing the oscillating magnetic field, generating a central sensor signal by a central sensor element arranged in a central region of the circle in the sensor plane; generating a phase shift measurement signal using the central sensor signal; and generating a second pulsed output signal based on the phase shift measurement signal and the selected differential measurement signal.

19. The method of claim 16, wherein the circle has a central axis about which the magnetic sensor is twisted to reach different twisted orientations having different twist angles relative to a reference direction, the method further comprising: determining a twist angle of the magnetic sensor relative to the reference direction based on the selected differential measurement signal.

20. The method of claim 16, wherein: the circle has a central axis about which the magnetic sensor is twisted to reach different twisted orientations having different twist angles relative to a reference direction, and the amplitudes of each of the plurality of differential measurement signals change based on the twist angle of the magnetic sensor.

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