METHOD FOR DETECTING THE RAD PITCH ON THE CHIP FOR MAGNETORESISTIVE SENSORS

Abstract

Sensor device which features: a first sensor arrangement (S) comprising a plurality of first sensor elements (S1-S4) configured to generate first sensor signals based on the detection of a changing magnetic field generated by a pole wheel (11) with a pole wheel pitch, wherein the first sensor signals include a first differential signal (D sp ), which defines a first measured value; a second sensor arrangement (D) comprising at least a second sensor element (D1-D6) configured to generate at least a second sensor signal based on the detection of the changing magnetic field generated by the pole wheel (11), wherein the at least one second sensor signal defines a second measured value that is phase-shifted with respect to the first measured value; a first amplifier circuit (21) configured to receive and amplify the first sensor signals in order to generate amplified first sensor signals; a second amplifier circuit (22) configured to receive and amplify the at least one second sensor signal in order to generate at least one amplified second sensor signal; and a sensor circuit (20) configured to convert the amplified first sensor signals into the first differential signal (D sp ) to convert the first measured value and to convert at least one amplified second sensor signal into a measurement signal (D dir ) to convert with the second measured value, wherein the sensor circuit (20) includes a signal processor (27) configured to determine the flywheel pitch based on the first measurement and the second measurement and to adjust a gain setting of the second amplifier circuit (22) based on the determined flywheel pitch.

Description

BACKGROUND

[0001] Magnetic speed sensors are used for speed measurement in numerous applications across many industries, including the automotive sector, for measuring wheel speed, engine speed, transmission speed, and more. In speed measurement, a magnetic sensor can generate a sinusoidal signal in response to the rotation of a target object, such as a wheel, camshaft, crankshaft, or similar component. This sinusoidal signal can be converted into pulses, which in turn can be used for motion detection or speed output.

[0002] Information from a velocity sensor can generate a velocity signal, from which the speed of the target object can be determined, and a direction signal, which, in combination with the velocity signal, indicates the direction of rotation of the target object's movement. Thus, a velocity sensor can generate both a velocity signal and a direction signal. Based on one or both of these signals, additional output signals (e.g., pulsed output signals) are generated, which provide sensor information to a microcontroller that uses the pulsed output signal.

[0003] A sensor element pitch is the lateral center-to-center distance between two magnetic field sensor elements arranged along a direction of rotation of the target object.

[0004] A pitch of a rotor is the center-to-center distance along a pitch circle between two adjacent poles of the same polarity (i.e., between two adjacent positive poles or two adjacent negative poles). Between two adjacent poles of the same polarity lies a pole of the opposite polarity. Therefore, a half-pitch of a rotor is the center-to-center distance between two adjacent poles of different (i.e., opposite) polarity on a pitch circle. In other words, the half-pitch is the distance along a pitch circle between the center point of a positive pole and the center point of a negative pole that is adjacent to the positive pole.

[0005] For optimal system performance, the sensor element pitch of an integrated circuit (IC) and the wheel's half-pitch should be matched (1:1). In other words, the sensor element pitch should be half the wheel's pitch (1:2). This ratio provides a better signal-to-noise ratio. Unfortunately, this isn't always possible, as the same sensor IC can be designed for different platforms that use different wheels with varying pitches. If the sensor element pitch and wheel's half-pitch are not matched, performance degradation can occur.

[0006] Publication US 2013 / 0328550A1 discloses a magnetic sensor arrangement for determining information about the properties of a mechanical component. The arrangement comprises a first magnetic sensor for detecting a signal generated by the relative movement of the component to the sensor and its periodically changing magnetic field, and a second magnetic sensor for detecting this signal. The first sensor is positioned at a fixed distance from the second sensor. An evaluation unit is coupled to the first and second sensors and receives their output signals. The output signal of the first sensor is phase-shifted relative to the output signal of the second sensor to compare the output signals and determine the absolute phase of the signal from the periodically changing magnetic field. Information about the properties of the mechanical component is derived from this determined absolute phase.

[0007] Therefore, the aim of the invention can be seen as providing an improved magnetic field sensor that is capable of determining the wheel pitch and performing compensation based thereon, which is desirable. OVERVIEW

[0008] The aforementioned objective is achieved by the sensor device of claims 1 and 16 and by the method of claim 18. Various embodiments and further developments are covered by the dependent claims. According to one embodiment, a sensor device comprises: a first sensor arrangement containing a plurality of first sensor elements configured to generate first sensor signals based on the detection of a changing magnetic field generated by a pole wheel with a pole wheel pitch, wherein the first sensor signals represent a first differential signal defining a first measured value;a second sensor arrangement comprising at least a second sensor element configured to generate at least a second sensor signal based on the detection of the changing magnetic field generated by the pole wheel, wherein the at least one second sensor signal defines a second measured value that is phase-shifted relative to the first measured value; a first amplifier circuit configured to receive and amplify the first sensor signals to generate amplified first sensor signals; a second amplifier circuit configured to receive and amplify the at least one second sensor signal to generate at least one amplified second sensor signal;and a sensor circuit configured to convert the amplified first sensor signals into the first differential signal containing the first measured value and to convert at least one amplified second sensor signal into a measurement signal containing the second measured value. The sensor circuit includes a signal processor configured to determine the rotor pitch based on the first and second measured values ​​and to adjust a gain setting of the second amplifier circuit based on the determined rotor pitch.

[0009] According to a further embodiment, a sensor device comprises: a first sensor arrangement comprising a plurality of first sensor elements configured to generate first sensor signals based on the detection of a changing magnetic field generated by a pole wheel with a pole wheel pitch, wherein the first sensor signals represent a first differential signal defining a first measured value; a second sensor arrangement comprising at least one second sensor element configured to generate at least one second sensor signal based on the detection of the changing magnetic field generated by the pole wheel, wherein the at least one second sensor signal defines a second measured value that is phase-shifted relative to the first measured value; a first amplifier circuit configured to receive and amplify the first sensor signals to generate amplified first sensor signals;a second amplifier circuit designed to receive and amplify at least one second sensor signal in order to generate at least one amplified second sensor signal;and a sensor circuit configured to convert the amplified first sensor signals into the first differential signal containing the first measured value and to convert the at least one amplified second sensor signal into a measurement signal containing the second measured value. The sensor circuit includes a signal processor configured to correlate a combination of the first and second measured values ​​with a corresponding gain setting from a plurality of gain settings, to select the corresponding gain setting from the plurality of gain settings based on the combination of the first and second measured values, and to set the selected corresponding gain setting as the gain setting of the second amplifier circuit.

[0010] Further embodiments provide a method for calibrating a magnetic field sensor circuit based on the pitch of a rotor. According to one embodiment, the method includes: generating first sensor signals by a first sensor arrangement based on the detection of a changing magnetic field generated by the rotor, wherein the first sensor signals represent a first differential signal defining a first measured value; generating at least one second sensor signal by a second sensor arrangement based on the detection of the changing magnetic field generated by the rotor, wherein the at least one second sensor signal defines a second measured value that is phase-shifted relative to the first measured value; amplifying the first sensor signals by a first amplifier circuit to generate amplified first sensor signals;The amplification of at least one second sensor signal by a second amplifier circuit to generate at least one amplified second sensor signal; the conversion of the amplified first sensor signals by a sensor circuit into the first differential signal containing the first measured value; the conversion of at least one amplified second sensor signal by the sensor circuit into a measurement signal containing the second measured value; the correlation of a combination of the first and second measured values ​​by the sensor circuit with a corresponding gain setting from a plurality of gain settings; the selection of the corresponding gain setting from the plurality of gain settings based on the combination of the first and second measured values ​​by the sensor circuit;and setting the selected corresponding gain setting as the gain setting of the second amplifier by the sensor circuit.; BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The embodiments are described here with reference to the attached drawings. Fig. Figure 1A illustrates a magnetic field detection principle using a pole wheel according to one or more embodiments; Fig. 1B and Fig. Figure 1C illustrates a pitch-alignment principle according to one or more embodiments; Fig. Figure 2 is a schematic block diagram illustrating a magnetic speed sensor according to one or more embodiments; Fig. 3A is a schematic representation of a first sensor arrangement with a preamplifier according to one or more embodiments; Fig. Figure 3B is a schematic representation of a second sensor arrangement with a preamplifier according to one or more embodiments; and Fig. Figure 3C shows a schematic block diagram of a speed sensor arrangement and a direction sensor arrangement of a magnetic speed sensor according to one or more embodiments. DETAILED DESCRIPTION

[0012] Details are set forth below to provide a more precise explanation of the exemplary embodiments. However, it will be clear to those skilled in the art that the embodiments can also be implemented without these specific details. In other cases, well-known structures and devices are presented in the form of a block diagram or a schematic view, rather than in detail, to avoid obscuring the embodiments. Furthermore, features of the various embodiments described below can be combined unless expressly stated otherwise. It is also understood that other embodiments can be used and structural or logical modifications can be made without departing from the scope defined by the claims. The following detailed description should therefore not be interpreted as restrictive.

[0013] Furthermore, equivalent or similar elements, or elements with equivalent or similar functionality, are designated with equivalent or similar reference numbers in the following description. Since identical or functionally equivalent elements in the figures are assigned the same reference numbers, repeated descriptions for elements with the same reference numbers are unnecessary. Therefore, descriptions for elements with the same or similar reference numbers are interchangeable.

[0014] Directional terminology such as "above," "below," "above," "below," "front," "back," "behind," "ahead," "behind," "over," "below," etc., may be used in relation to the orientation of the described figures and / or elements. Since the embodiments can be positioned in a number of different orientations, the directional terminology is used for illustrative purposes and is in no way restrictive. In some cases, the directional terminology based on the orientation of an embodiment may be replaced by equivalent directional terminology, provided that the general directional relationships between elements and their overall purpose are maintained.

[0015] In the present disclosure, expressions containing ordinal numbers such as "first," "second," and / or the like may modify various elements. However, such elements are not restricted by the above expressions. For example, the above expressions do not restrict the order and / or meaning of the elements. The above expressions are used solely for the purpose of distinguishing one element from the other elements. For example, a first container and a second container denote different containers, although both are containers. As another example, a first element could be referred to as a second element, and similarly, a second element could also be referred to as a first element, without this deviating from the scope of the present disclosure.

[0016] It is understood that when an element is described as "connected" or "coupled" to another element, it may be directly connected or coupled to that other element, or there may be intervening elements. Conversely, when an element is described as "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between elements should be interpreted similarly (e.g., "between" as opposed to "directly between," "adjacent" as opposed to "directly adjacent," etc.).

[0017] In the embodiments described herein or illustrated in the drawings, any direct electrical connection or coupling, i.e., any connection or coupling without any additional intervening elements, can also be realized 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, for example, to send a certain type of signal or to transmit a certain type of information, is essentially maintained. Features from different embodiments can be combined to form further embodiments. For example, variations or modifications described in relation to one embodiment may also be applicable to other embodiments unless otherwise noted.

[0018] Depending on specific implementation requirements, a storage medium may contain RAM, ROM, PROM, EPROM, EEPROM, FLASH memory, or any other medium containing electronically readable control signals that interact (or can interact) with a programmable computer system to execute the procedure in question. Therefore, a storage medium can be considered a non-volatile, computer-readable storage medium.

[0019] Additionally, instructions can be executed by one or more processors, such as one or more central processing units (CPUs), digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete circuits. Accordingly, the term "processor," as used herein, refers to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. Furthermore, some aspects of the functionality described herein can be provided by dedicated hardware and / or software modules.The techniques could also be fully implemented in one or more circuits or logic elements. A "controller," containing one or more processors, can use electrical signals and digital algorithms to perform its receptive, analytical, and control functions, which may further include correction functions.

[0020] A sensor can refer to a component that converts a physical quantity to be measured into an electrical signal, for example, a current signal or a voltage signal. The physical quantity can be, for example, a magnetic field, an electric field, pressure, force, temperature, current, or voltage, but is not limited to these. A sensor device, as described here, can be a voltage sensor, a current sensor, a temperature sensor, a magnetic sensor, and the like.

[0021] A magnetic field sensor, for example, contains one or more magnetic field sensor elements that measure one or more properties of a magnetic field (e.g., the magnitude of the magnetic flux density, the field strength, the field angle, the field direction, the field orientation, etc.). The magnetic field can be generated by a magnet, a current-carrying conductor (e.g., a wire), the ground, or another magnetic field source. Each magnetic field sensor element is designed to generate a sensor signal (e.g., a voltage signal) in response to one or more magnetic fields applied to the sensor element. Thus, a sensor signal allows conclusions to be drawn about the strength and / or orientation of the magnetic field applied to the sensor element.

[0022] Magnetic field sensor elements include magnetoresistive sensors, often referred to as XMR sensors, which is a collective term for, but not limited to, anisotropic magnetoresistive (AMR) sensors, giant magnetoresistive (GMR) sensors, tunnel magnetoresistive (TMR) sensors, etc. The sensor circuit can be described as a signal processing circuit and / or signal conditioning circuit, which 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 from the sensor signal that represents the magnetic field.

[0023] In some cases, a measurement signal can be a differential signal, derived using differential arithmetic from sensor signals generated by two sensor elements with the same measurement axis (e.g., two sensor elements sensitive to the same magnetic field component). A differential signal offers robustness against homogeneous external stray magnetic fields.

[0024] Signal conditioning, as used here, refers to manipulating an analog signal in such a way that the signal meets the requirements of a subsequent processing stage. Signal conditioning can include analog-to-digital conversion (e.g., via an analog-to-digital converter), amplification, filtering, conversion, biasing, range matching, isolation, and any other processes necessary to make a sensor output signal suitable for post-conditioning processing.

[0025] The sensor circuit can include an analog-to-digital converter (ADC) that converts the analog signal from one or more sensor elements into a digital signal. The sensor circuit can also include a digital signal processor (DSP) that performs some processing on the digital signal, which will be discussed further below. Therefore, a chip, which can also be called an integrated circuit (IC), can contain a circuit that conditions and amplifies the small signal from one or more magnetic field sensor elements through signal processing and / or conditioning.

[0026] A sensor device, as used here, can refer to a device that includes a sensor and a sensor circuit as described above. A 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 located on the same semiconductor die.

[0027] The magnetic field sensors provided here can be configured for speed and direction of rotation measurements of a rotating magnetic encoder, such as a wheel or camshaft, referred to as the target object or target wheel. Magnetic field sensors can also measure the magnetic phase, where a magnetic period is correlated in 360 degrees.

[0028] One type of magnetic encoder is a pole wheel consisting of alternating magnets magnetized in opposite directions (e.g., alternating south and north pole magnets) arranged around the encoder's circumference. In this case, the speed sensor is positioned in front of or on the side of the pole wheel, with the distance between the sensor module and the pole wheel defined by an air gap. The sensor module detects when the measured magnetic field changes its polarity. In this case, the speed sensor generates an output signal indicating that one pole has passed.

[0029] Fig. Figure 1A illustrates a magnetic field detection principle using a pole wheel according to one or more embodiments.

[0030] A sensor module 1 is a velocity sensor comprising a first sensor element assembly and a sensor circuit (not shown). The first sensor element assembly is a first sensing structure containing two differential magnetic field sensor elements, SE1 and SE2. The sensor signals from each differential sensor element, SE1 and SE2, are fed to the sensor circuit, which calculates a differential measurement signal using a differential calculation that can be used to cancel out homogeneous stray fields in the directions of the sensor plane. A sensor element pitch is the lateral center-to-center distance between the two magnetic field sensor elements, SE1 and SE2, arranged along a direction of rotation of the target object (i.e., the pole wheel 11).

[0031] The sensor arrangement is designed to detect a magnetic field generated by the pole wheel 11. The sensor arrangement can generally be referred to here as a velocity sensor arrangement and may furthermore include a sensor circuit (not shown) and be arranged in a sensor package.

[0032] The pole wheel 11 is a magnetized encoder wheel having alternating north pole sections 12 and south pole sections 13. The sensor elements SE1 and SE2 are sensitive to magnetic fields influenced by the north pole sections 12 and the south pole sections 13 of the pole wheel 11. A pole wheel pitch is the center-to-center distance along a pitch circle between two adjacent poles of the same polarity (i.e., between two adjacent positive poles or two adjacent negative poles). Between two adjacent poles of the same polarity is a pole of opposite polarity. A pole wheel half-pitch is therefore the center-to-center distance between two adjacent poles of different (i.e., opposite) polarity along a pitch circle.In other words, the half-pitch is the distance between the center point of a positive pole and the center point of a negative pole adjacent to the positive pole along a partial circle.

[0033] For optimal system performance, the sensor element pitch of an integrated sensor circuit (IC) and half the wheel pitch should be matched (1:1). In other words, the sensor element pitch should be half the wheel pitch (1:2). This ratio provides a better signal-to-noise ratio.

[0034] In practice, sensor elements SE1 and SE2 can each have a sensitivity axis aligned in the x-direction, making them sensitive to an x-component Bx of the magnetic field generated by the pole wheel. Since their sensitivity axis is aligned with the x-component Bx of the magnetic field, sensor elements SE1 and SE2 generate electrical signals that are representative of, or proportional to, the magnitude of, the x-component Bx. The sensor circuit of the sensor assembly generates a sensor output signal corresponding to the rotational speed of the magnetized encoder wheel 11 by detecting the change in the alternating magnetic field generated by alternating north and south poles passing the sensor assembly as the pole wheel 11 rotates about its axis of rotation 14.

[0035] As the pole wheel 11 rotates, the positive poles 12 and the negative poles 13 alternately pass by the sensor module 1, and the sensor elements within the sensor arrangement detect a change in the magnetic field strength in the x or y direction, which changes as a sinusoidal waveform (i.e. as a signal modulation), the frequency of which corresponds to a rotational speed of the wheel and which also corresponds to a rotational speed of a drive shaft (e.g. camshaft) that drives the rotation of the wheel.

[0036] The sensor circuit of the sensor array receives signals (i.e., sensor signals) from the magnetic field sensor elements SE1 and SE2 and derives a differential measurement signal from these signals, representing the magnetic field as a signal modulation. This differential measurement signal can then be output to an external controller, control unit, or processor (e.g., an ECU) or used internally by the sensor circuit for further processing (e.g., to generate a pulsed output signal) before being sent to the external device. For example, the external device can count the pulses of the pulsed output signal and calculate a wheel speed from this count. The differential measurement signal can be referred to as a speed signal, from which the speed of the target object can be determined.

[0037] Furthermore, the sensor module 1 can include a second sensor array as a second sensing structure, which is used to generate a direction signal that, in combination with the speed signal, allows conclusions to be drawn about the direction of rotation (e.g., clockwise or counterclockwise) of the pole wheel 11. This second sensing structure comprises a single mono-cell sensor element SE3 (i.e., a third magnetic field sensor element) positioned midway between the two differential sensor elements SE1 and SE2 of the first sensing structure to enable the sensor to detect the direction of rotation of the wheel 11. The sensor element SE3 can also have a sensitivity axis aligned in the x-direction.

[0038] In particular, the first sensor array can be configured to generate a velocity sensor signal, and the second sensor array can be configured to generate a direction sensor signal that is phase-shifted by 90° or substantially 90° relative to the velocity sensor signal. The phase shift between the velocity signal and the direction signal can be evaluated by the sensor circuit, and the direction of rotation of a target object can be determined based on whether the phase shift is positive or negative. For example, differential sensor elements SE1 and SE2 can be used to generate a sinusoidal velocity signal, and the third sensor element SE3 can be used to generate a sinusoidal (cosine) direction signal that is phase-shifted by 90° relative to the velocity signal. By monitoring the direction of the phase shift (e.g.,(positive or negative) the sensor circuit can determine the direction of rotation of the magnetic field and thus of the target object.

[0039] While the second sensing structure is shown as being formed as a single-cell sensor element, it will be recognized that the second sensor structure can also have a plurality of sensor elements used to generate a differential sensor signal that is phase-shifted by 90° or essentially 90° relative to the velocity sensor signal, which is also a differential signal. The phase shift is caused by the geometric arrangement of the sensor elements (e.g., SE1, SE2, and SE3) relative to each other.

[0040] Furthermore, it will be recognized that the first sensor array for generating the velocity sensor signal can consist of two or more sensor elements, while the second sensor array for generating the direction sensor signal can consist of one or more sensor elements. In the case of a sensor array containing two or more sensing elements, the sensing elements of the respective sensor array can be arranged in a differential configuration and / or a bridge configuration. For example, sensor elements used to generate a velocity sensor signal can contain four or more sensor elements arranged in a bridge configuration that outputs the velocity sensor signal as a first differential signal.Similarly, sensor elements used to generate a direction sensor signal can contain four or more sensor elements arranged in a bridge configuration that outputs the direction sensor signal as a second differential signal.

[0041] Fig. Figures 1B-1C illustrate a pitch-alignment principle according to one or more embodiments. As discussed above, this shows Fig. 1A a magnetized encoder wheel 11 and a first sensor arrangement (SE1 and SE2) with a sensor element pitch that is matched 1:1 to the pole wheel half-pitch.

[0042] Fig. Figure 1B shows a graph of an oscillating magnetic field generated by the magnetized encoder wheel 11 and projected onto the wheel speed sensor, in a case where the pitches are ideally matched (i.e., the sensor element pitch is matched to the pole wheel half-pitch). As can be seen, the peak-to-peak amplitude of a differential sensor signal (Bdiff,max) is equal to twice the maximum amplitude of the x-component Bx of the magnetic field that can be detected at the wheel speed sensor (e.g., based on the constant air gap between the wheel speed sensor and the wheel). The peak-to-peak amplitude is, in this case, the maximum value that can be detected by the sensor.

[0043] Fig. Figure 1C shows a graph of an oscillating magnetic field generated by the magnetized encoder wheel 11 and projected onto the wheel speed sensor in a case where the pitches are mismatched (i.e., when the sensor element pitch is not matched to the pole wheel half-pitch). As can be seen, the peak-to-peak amplitude of a differential sensor signal (Bdiff,max) is higher than that shown in Figure 1C. Fig. The peak-to-peak amplitude shown in 1B is damped. Thus, the peak-to-peak amplitude in Fig. 1C less than twice the maximum amplitude of the x-component Bx of the magnetic field that could be detected at the wheel speed sensor (e.g. based on the constant air gap between the wheel speed sensor and the wheel) if the pitch mismatch did not exist.

[0044] Further embodiments are described that are capable of determining the wheel pitch and performing compensation on a sensor signal based on the determined wheel pitch or half-pitch. In the case of speed sensors, such as anti-lock braking system (ABS) speed sensors, direction detection is also present. The speed sensor signal and the direction sensor signal are converted into digital signals (i.e., digital values) by the sensor circuit (which includes, for example, an ADC). The sensor circuit is further configured to determine the wheel pitch using a lookup table, either by dividing the two values ​​and checking them against a lookup table, or by another algorithm.

[0045] Fig. Figure 2 is a schematic block diagram showing a magnetic velocity sensor 100 according to one or more embodiments. The magnetic velocity sensor 100 comprises a sensor assembly S and a sensor assembly D, each configured to generate a differential sensor signal in response to an applied magnetic field. In particular, the sensor assembly S can comprise a first group of magnetic field sensor elements arranged in a bridge circuit configuration and configured to generate a velocity sensor signal. Similarly, the sensor assembly D can comprise a second group of magnetic field sensor elements arranged in a bridge circuit configuration and configured to generate a direction sensor signal that is phase-shifted relative to the velocity sensor signal, for example by 90°.The phase shift between the velocity signal and the direction signal can be evaluated, and based on whether the phase shift is positive or negative, the direction of rotation of a target object can be determined. It will also be recognized that the sensor assembly D can be a mono-cell magnetic sensor element (i.e., having only a single sensor element), as described above. If the sensor assembly D is a mono-cell magnetic sensor, the sensor signal generated by the mono-cell sensor element is used as the direction signal.

[0046] The in Fig. The sensor arrangements S and D shown in Figure 2 can each represent a magnetoresistive bridge containing a corresponding set of sensor elements arranged in a bridge configuration. The sensor elements of sensor arrangement S are configured to measure magnetic fields along a common sensing plane (e.g., x-plane, y-plane, or z-plane). Similarly, the sensor elements of sensor arrangement D are configured to measure magnetic fields along a common sensing plane (e.g., x-plane, y-plane, or z-plane). That is, the sensor elements forming a bridge have reference directions aligned in a common sensing plane.

[0047] The magnetic velocity sensor 100 also includes a sensor circuit 20, which receives the sensor signals from the sensor assemblies S and D for processing and generating a pulsed output velocity signal and a direction indicator signal at output OFF. The sensor circuit 20 has two signal paths: an S signal path and a D signal path. The differential velocity (S) signal on the S signal path can be in the form of a sinusoidal waveform representing the rotational velocity of the target object, and the differential direction (D) signal on the D signal path can be a similar waveform that is phase-shifted relative to the velocity signal, for example, by 90°.For example, the direction signal can be a cosine waveform representing a rotational speed of the target object, but is used by a digital signal processor 27 to determine the direction of rotation by analyzing the phase difference between the speed signal and the direction signal.

[0048] The signal paths S and D can each contain a preamplifier Asp 21 and Adir 22 as well as differential comparators 23 and 24, which output their respective differential signals to corresponding ADCs 25 and 26.

[0049] The sensor array S generates differential sensor signals, between which a differential measurement value, such as a voltage difference Vdiff,speed, exists. The preamplifier Asp 21 amplifies these differential sensor signals according to a defined gain and delivers the amplified differential sensor signals to the differential comparator 23. The differential comparator 23 converts the differential sensor signals into an analog differential measurement signal that has a value equal to the voltage difference Vdiff,speed. The ADC 25 converts the analog differential measurement signal into the digital domain, specifically into a digital differential measurement signal that corresponds to the voltage difference Vdiff,speed.

[0050] Similarly, the sensor array D generates at least one sensor signal. If the sensor array D is a single-cell array, a signal sensor element is provided to generate a sensor signal that is phase-shifted by 90° relative to the analog differential measurement signal of the velocity signal path. In this case, the differential comparator 24 would not be required. Instead, the preamplifier Adir 22 amplifies the sensor signal received from the sensor array D according to a defined gain, and the ADC 26 converts the amplified sensor signal into the digital domain. Consequently, the signal processor 27 receives a first digital signal from the velocity path and a second digital signal from the direction path, which is phase-shifted by a predetermined amount (e.g., 90°) relative to the first digital signal.

[0051] Alternatively, the sensor arrangement D can generate differential sensor signals, for example via a bridge arrangement, where the differential sensor signals have a differential measurement value, such as a voltage difference Vdiff,dir, between them. The preamplifier Asp 22 amplifies these differential sensor signals according to a set gain and supplies the amplified differential sensor signals to the differential comparator 24. The differential comparator 24 converts the differential sensor signals into an analog differential measurement signal whose value is equal to the voltage difference Vdiff,dir. The ADC 26 converts the analog differential measurement signal into the digital domain, specifically into a digital differential measurement signal representing the voltage difference Vdiff,dir. Consequently, the signal processor 27 receives a first digital signal (i.e., a digital velocity signal Dsp) from the velocity path and a second digital signal (i.e.,a digital direction signal Ddir) from the direction path, which is phase-shifted relative to the first digital signal by a predetermined phase shift (e.g. 90°).

[0052] The digital signal processor 27 is configured to receive the digital velocity signal and the digital direction signal for further processing, which includes determining the velocity and direction of rotation of the target object. Additionally, the signal processor 27 is configured to automatically determine the wheel pitch based on the velocity and direction signals and to compensate for or condition the velocity and / or direction signals based on the determined wheel pitch. For example, the digital signal processor 27 can contain one or more processors and / or logic units that perform various signal conditioning functions, such as absolute signal conversion, normalization, linearization, frequency enhancement, and so on. One or more signal conditioning functions can be performed in combination with a lookup table stored in memory.The OFF output of the digital signal processor 27 can supply one or more output signals to an external device such as an ECU.

[0053] For example, the rotational speed of the target object can be output as a velocity pulse signal. The sinusoidal signal generated by the sensor arrangement S can be converted into pulses by the signal processor 27, which in turn can be used for motion detection or velocity output. Furthermore, based on the evaluation of the phase shift between the digital velocity signal and the digital direction signal, the signal processor 27 can output a signal indicating the direction of rotation.

[0054] To determine the wheel pitch, the signal processor 27 evaluates the difference between the amplitude of the digital velocity signal Dsp and the amplitude of the digital direction signal Ddir. For example, the signal processor 27 can use one or more lookup tables to evaluate the difference, it can use a CORDIC (coordinate rotation digital computer) operation that calculates a ratio R of the digital velocity signal Dsp and the digital direction signal Ddir (e.g., R = Dsp / Ddir or R = Dir / Dsp), or it can use a combination of these methods. Based on the determined wheel pitch, the signal processor 27 adjusts the gain setting of the preamplifier Adir 22 via a gain controller 28 so that the ratio R is approximately or equal to 1:1.In other words, the gain controller 28 is configured to adjust the gain of the preamplifier Adir 22 such that the maximum and minimum amplitude of the digital direction signal Ddir are essentially equal to the maximum and minimum amplitude of the digital speed signal Dspeed. In this way, the signal processor 27 enables the sensor 100 to automatically adapt to different rotor pitches in order to adjust the signal behavior according to the specified parameters. Fig. To optimize the ideal pitch adjustment shown in 1B.

[0055] Fig. Figure 3A is a schematic representation of a first sensor arrangement with a preamplifier according to one or more embodiments. Fig. Figure 3B is a schematic representation of a second sensor arrangement with a preamplifier according to one or more embodiments. Fig. Figure 3C shows a schematic block diagram of a speed sensor arrangement and a direction sensor arrangement of a magnetic speed sensor according to one or more embodiments.

[0056] In particular, the first sensor arrangement corresponds to sensor arrangement S with four sensor elements S1-S4 arranged in a first bridge configuration connected between a first and a second supply terminal, and the second sensor arrangement corresponds to sensor arrangement D with six sensor elements D1-D6 arranged in a second bridge configuration connected between the first and second supply terminals. It will be recognized that sensor arrangements S and D are not limited with respect to either the number of sensor elements or the bridge configurations shown.

[0057] The magnetic sensor bridge circuit S comprises a first magnetoresistive sensor element S1 and a fourth magnetoresistive sensor element S4. The first and fourth magnetoresistive sensor elements S1 and S4 are connected in series. The magnetic sensor bridge circuit S also comprises a second magnetoresistive sensor element S2 and a third magnetoresistive sensor element S3. The second and third magnetoresistive sensor elements S2 and S3 are connected in series. The first and second magnetoresistive sensor elements S1 and S2 are connected to a first supply terminal of the magnetic sensor bridge circuit S. The third and fourth magnetoresistive sensor elements S3 and S4 are connected to a second, different supply terminal of the magnetic sensor bridge circuit S.

[0058] The magnetic sensor bridge circuit D comprises a first magnetoresistive sensor element D1 and a second magnetoresistive sensor element D2, which are connected in parallel and further connected in series with a third magnetoresistive sensor element D3. The magnetic sensor bridge circuit D also comprises a fourth magnetoresistive sensor element D4, which is connected in series with a fifth magnetoresistive sensor element D5 and a sixth magnetoresistive sensor element D6, which are connected in parallel with each other. Connections to the first and second supply terminals are also provided.

[0059] The differential sensor signals generated by sensor arrangements S and D are amplified by corresponding preamplifiers Asp 21 and Adir 22, respectively. The amplified differential sensor signals have a difference value between them, represented by Vdiff,speed and Vdiff,dir. The gain setting of preamplifier Adir 22 is adjustable so that the extreme of Vdiff,dir is equal to or substantially equal to the extreme of Vdiff,speed, albeit shifted by 90° relative to each other.

[0060] Fig. Figure 3C shows an example arrangement of sensor elements S1-S4 and D1-D6, which are arranged linearly on a sensor chip (e.g., on an x-axis), with the sensor elements located in three different regions: a left region, a middle region, and a right region. The geometric center of the sensor arrangements is located at the first geometric center of the middle sensor elements D3 and D4. The effective sensor element pitch is defined by the distance between a second geometric center of the left sensor elements and a third geometric center of the right sensor elements. The second and third geometric centers are equidistant from the first geometric center.

[0061] Equation 1 below is a formula for calculating a damping factor for the velocity signal according to an adjustment of the rotor pitch (pitch). PW ) to the effective sensor element pitch (pitch SE) in a 1:2 ratio (i.e., the effective sensor element pitch is matched to half the rotor pitch). Equation 2 below is a formula for calculating a damping factor for the directional signal corresponding to an adjustment of the rotor pitch (pitch). PW ) to the effective sensor element pitch (pitch SE ) in a 1:2 ratio (i.e., the effective sensor element pitch is matched to the flywheel half-pitch). Equation 3 below is a formula for calculating a pitch mismatch ratio by dividing Equation 2 by Equation 1. Bdiff,spBx=2⋅sin(pitchSEpitchPW⋅π) Bdiff,dirBx=1−cos(pitchSEpitchPW⋅π) Bdiff,dirBdiff,sp=12⋅1−cos(pitchSEpitchPW⋅π)sin(pitc SEpitchPW⋅π)

[0062] As noted above, the signal processor can implement a lookup table procedure for detecting a rotor pitch and adjusting the gain of preamplifier Adir 22 accordingly. Two or more rotor pitches can be known and programmed into the lookup table. In the following examples, rotor pitches of 4.4 mm and 5.7 mm are correlated with the total amplitude values ​​of the digital measurement signals Dsp and Ddir (see: Lookup Table 1) or with the value of the least significant bit (LSB) of the digital measurement signals Dsp and Ddir (see: Lookup Table 2). Zeile # Dsp [µT] Ddir_4,4 mm [µT] Ddir_5,7 mm [µT] 1 180 56 41 2 232 72 53 3 299 92 68 ... ... ... ... REFERENCE TABLE 1

[0063] According to reference table 1, the signal processor 27 is configured to distinguish between two predefined wheel pitches and to identify which wheel pitch is present in front of the speed sensor 100. To perform this determination, the signal processor 27 is configured to select a row from the table based on the measured amplitude value of the digital speed signal Dsp. Once a row is selected, the signal processor 27 evaluates the measured amplitude value of the digital direction signal Ddir to select a corresponding wheel pitch specified in the second and third columns. For example, if the amplitude value of the digital speed signal Dsp is 102, the second row is selected.After selecting the second line, an amplitude value of 95 for the digital direction signal Ddir indicates that the wheel pitch is 4.4 mm, and an amplitude value of 70 for the digital direction signal Ddir indicates that the wheel pitch is 5.7 mm. Based on the determined wheel pitch, the gain controller 28 is configured to set a gain setting for the preamplifier Adir 22 for the direction signal, which is specified for the wheel pitch. That is, each programmed wheel pitch has a corresponding gain setting that is implemented by the gain controller 28. Zeile # Dsp [LSB] Ddir_4,4mm [LSB] Ddir_5,7mm [LSB] 1 79 73 54 2 102 95 70 3 132 122 90 ... ... ... ... REFERENCE TABLE 2

[0064] A similar method can be implemented by using the least significant bits (LSB) of the digital speed signal Dsp and the digital direction signal Ddir with a predetermined number of bits, as shown in Reference Table 2. Here, “LSB” represents the number of bits of the ADC that digitizes the speed and direction signals. The ADC output has a range [0; 2 N - 1 ], where N is the number of bits of the ADC. Therefore, the digital values ​​in the table above are those to be compared with the digital values ​​output by ADCs 25 and 26.

[0065] The rule for constructing a correct lookup table is to ensure that the areas of Ddir_4.4mm (area for the differential velocity field in the case of a wheel pitch of 4.4 mm) do not overlap with the areas of Ddir_5.7mm (area for the differential direction field in the case of a wheel pitch of 5.7 mm). Since the amplitude values ​​are larger when the wheel pitch of the reference wheel is smaller, the values ​​in the Ddir_4.4mm column are larger than their corresponding values ​​in the Ddir_5.7mm column in the same row.

[0066] The signal processor 27 can also apply pseudocode to change the applied gain of the directional preamplifier Adir 22. An example of pseudocode is as follows:

[0067] In this way, a chain of if-then-else statements can be formalized or implemented by a logic circuit used to distinguish the wheel pitch and select an appropriate gain setting based on the combination of the first and second measured values ​​that satisfy one of the if-then-else statements. The if-then-else statements can be used in the code to confirm certain conditions for applying different gain settings (dir_gain_pre-amp) to the directional preamplifier Adir 22. The signal processor 27 is configured to select the appropriate gain setting based on if-then-else statements, with the signal processor determining the appropriate gain setting based on a combination of the digital speed signal Dsp (e.g., an amplitude value thereof) and the digital direction signal Ddir (e.g.,The program selects a signal (based on an amplitude value) that satisfies one of the if-then-else statements. Additional lines of code (e.g., additional logic in the logic circuit) can be added for additional gain settings corresponding to additional wheel pitches, with additional conditions based on speed and direction signal amplitudes being added to distinguish the correct wheel pitch.

[0068] Furthermore, CORDIC operations are capable of calculating the division between two values. Therefore, the signal processor 27 can be configured to divide the amplitude of the velocity signal by the amplitude of the direction signal to determine a ratio. In the case of a wheel pitch of 4.4 mm, the ratio is close to 1, since the direction path is designed such that the LSB14 signal amplitude in the digital domain is nearly one to one. If the division between velocity and direction amplitudes results in a ratio equal to or greater than a predefined ratio (e.g., equal to or greater than 1.3), the signal processor 27 is configured to increase the gain setting for the direction preamplifier from 24 to 32, where, in this example, 32 is the optimized gain for a wheel pitch of 5.7 mm and 24 is the optimized gain for a wheel pitch of 4.4 mm.Conversely, if the ratio is smaller than the specified ratio (e.g., smaller than 1.3), the signal processor 27 is configured to set, maintain, or decrease the directional pre-gain to a gain setting of 24. It will be observed that the number of ratio constants or ratio ranges increases with the number of possible pre-gain options and the number of available rotor pitches. This means that the number of ratio ranges increases, and the range of these ranges can become narrower, as more rotor pitches are programmed. Thus, multiple ratio ranges can be defined according to the number of rotor pitches that the signal processor 27 must distinguish.

[0069] With regard to the above, there are several ways in which the signal processor 27 can correlate a combination of the digital velocity signal Dsp (e.g., an amplitude value thereof) and the digital direction signal Ddir (e.g., an amplitude value thereof) with a corresponding gain setting from a plurality of gain settings, select the corresponding gain setting from the plurality of gain settings based on the combination of digital velocity and direction values, and set the selected corresponding gain setting as the gain setting of the direction preamplifier Adir 22.

[0070] The rotor pitch can be determined either explicitly or implicitly via lookup, code, and / or arithmetic, with the direction amplifier gain being selected based on the explicit or implicit determination of the rotor pitch. If it is determined explicitly, each rotor pitch can be explicitly mapped to a corresponding direction amplifier gain. Implicit mappings without explicitly determining the rotor pitch are also possible. Each of the plurality of gain settings stored in a memory of the sensor circuit 20 corresponds to one of a plurality of rotor pitches programmed in the memory of the sensor circuit 20. Thus, the plurality of gain settings is available for selection by the signal processor 27 (e.g., the gain controller 28) based on a selection algorithm.

[0071] While various embodiments have been disclosed, it will be obvious to those skilled in the art that various changes and modifications can be made which achieve some of the advantages of the concepts disclosed herein without departing from the idea and scope of the invention. It will be obvious to those skilled in the art that other components performing the same functions can be appropriately substituted. It is understood that other embodiments can be used and structural or logical changes can be made without departing from the scope of the present invention. It should be noted that features explained with reference to a particular figure can be combined with features of other figures, even those not expressly mentioned.Such modifications of the general invention concept are to be covered by the attached claims and their statutory equivalents.

[0072] Furthermore, the following claims are hereby included in the detailed description, each claim being capable of standing alone as a separate example embodiment. While each claim can stand alone as a separate example embodiment, it should be noted that—although a dependent claim may refer in the claims to a specific combination with one or more other claims—other example embodiments may also include a combination of the dependent claim with the subject matter of any other dependent or independent claim. Such combinations are proposed here unless it is stated that a particular combination is not intended. It is also intended to include features of a claim relating to any other independent claim, even if that claim is not directly dependent on the independent claim.

[0073] It should also be noted that methods disclosed in the description or in the claims can be implemented by a device that includes means for performing each of the respective actions of these methods. For example, the techniques described in this disclosure can be implemented, at least partially, in hardware, software, firmware, or any combination thereof. For example, various aspects of the described techniques can be implemented in one or more processors, including one or more microprocessors, DSPs, ASICs, or other equivalent integrated or discrete logic circuits, as well as any combination of such components.

[0074] Furthermore, it is understood that the disclosure of multiple acts or functions in the specification or in the claims may not be interpreted as constituting a specific sequence. Therefore, the disclosure of multiple acts or functions does not restrict them to a particular sequence unless such acts or functions are not interchangeable for technical reasons. Moreover, in some embodiments, a single act may contain or be subdivided into multiple sub-acts. Such sub-acts may be included in and form part of the disclosure of that single act unless expressly excluded.

Claims

[1] Sensor device comprising: a first sensor arrangement (S) comprising a plurality of first sensor elements (S1-S4) configured to generate first sensor signals based on the detection of a changing magnetic field generated by a pole wheel (11) with a pole wheel pitch, wherein the first sensor signals include a first differential signal (D sp ), which defines a first measured value; a second sensor arrangement (D) comprising at least a second sensor element (D1-D6) configured to generate at least a second sensor signal based on the detection of the changing magnetic field generated by the pole wheel (11), wherein the at least one second sensor signal defines a second measured value that is phase-shifted with respect to the first measured value; a first amplifier circuit (21) configured to receive and amplify the first sensor signals in order to generate amplified first sensor signals; a second amplifier circuit (22) configured to receive and amplify the at least one second sensor signal in order to generate at least one amplified second sensor signal; and a sensor circuit (20) configured to convert the amplified first sensor signals into the first differential signal (D sp ) to convert the first measured value and to convert at least one amplified second sensor signal into a measurement signal (D dir ) to convert with the second measured value, wherein the sensor circuit (20) includes a signal processor (27) configured to determine the flywheel pitch based on the first measurement and the second measurement and to adjust a gain setting of the second amplifier circuit (22) based on the determined flywheel pitch. [2] Sensor device according to claim 1, wherein the measurement signal (D dir ) compared to the first difference signal (D sp ) is shifted by 90°. [3] Sensor device according to claim 1 or 2, wherein the second sensor arrangement (D) comprises a plurality of second sensor elements (D1-D6) configured to generate second sensor signals based on the detection of the changing magnetic field generated by the pole wheel (11), wherein the second sensor signals represent a second differential signal (Dsp) that defines the second measured value. [4] Sensor device according to claim 3, wherein: the second amplifier circuit (22) is configured to receive and amplify the second sensor signals in order to generate amplified second sensor signals; the sensor circuit (20) is configured to convert the amplified second sensor signals into the measurement signal, wherein the measurement signal is the second differential signal (D sp ) with the second measurement is, the signal processor (27) is designed to determine the rotor pitch based on the first measurement and the second measurement and to adjust the gain setting of the second amplifier circuit (22) based on the determined rotor pitch. [5] Sensor device according to claim 4, wherein the first measured value is a first differential value (V diff,speed ) and the second measured value is a second difference value (V diff,dir ) is. [6] Sensor device according to one of claims 3 to 5, wherein the majority of the first sensor elements (S1-S4) are arranged in a first bridge circuit and the majority of the second sensor elements (D1-D6) are arranged in a second bridge circuit. [7] Sensor device according to any one of claims 1 to 6, wherein: the signal processor (27) is configured to correlate a combination of the first measurement and the second measurement with a corresponding gain setting from a plurality of gain settings, to select the corresponding gain setting from the plurality of gain settings based on the combination of the first measurement and the second measurement, and to define the selected corresponding gain setting as the gain setting of the second amplifier circuit (22). [8] Sensor device according to claim 7, wherein each of the plurality of gain settings corresponds to one of a plurality of pole wheel pitches programmed in a memory of the sensor circuit (20). [9] Sensor device according to claim 7 or 8, wherein: the signal processor (27) is configured to determine the rotor pitch using a lookup table, wherein the signal processor (27) determines the rotor pitch based on the combination of the first measurement and the second measurement within the lookup table and selects the appropriate gain setting based on the determined rotor pitch. [10] Sensor device according to any one of claims 7 to 9, wherein: the signal processor (27) is configured to select the appropriate gain setting using a lookup table, wherein the signal processor (27) selects the appropriate gain setting based on the combination of the first measurement and the second measurement within the lookup table. [11] Sensor device according to any one of claims 7 to 10, wherein: the signal processor (27) is configured to select the appropriate gain setting based on a logic circuit formalized by if-then-else instructions, wherein the signal processor (27) selects the appropriate gain setting based on the combination of the first measured value and the second measured value that satisfies one of the if-then-else instructions. [12] Sensor device according to any one of claims 7 to 11, wherein: the signal processor (27) is configured to calculate a ratio of the first measurement and the second measurement, to compare the ratio with at least one threshold value to generate a comparison result, and to select the appropriate gain setting based on the comparison result. [13] Sensor device according to any one of claims 7 to 12, wherein: the signal processor (27) is designed to select the appropriate gain setting based on a ratio of the first measurement and the second measurement. [14] Sensor device according to any one of claims 7 to 13, wherein: the signal processor (27) is designed to calculate a ratio of the first measured value and the second measured value, to determine a threshold range in which the ratio lies from a plurality of threshold ranges, and to select the appropriate gain setting based on the determined threshold range. [15] Sensor device according to one of claims 7 to 14, wherein the signal processor (27) is configured to calculate a ratio of the first measured value and the second measured value and to select the corresponding gain setting based on the ratio. [16] Sensor device comprising: a first sensor arrangement (S) comprising a plurality of first sensor elements (S1-S4) configured to generate first sensor signals based on the detection of a changing magnetic field generated by a pole wheel (11) with a pole wheel pitch, wherein the first sensor signals include a first differential signal (D sp ), which defines a first measured value; a second sensor arrangement (D) comprising at least a second sensor element (D1-D6) configured to generate at least a second sensor signal based on the detection of the changing magnetic field generated by the pole wheel (11), wherein the at least one second sensor signal defines a second measured value that is phase-shifted with respect to the first measured value; a first amplifier circuit (21) configured to receive and amplify the first sensor signals in order to generate amplified first sensor signals; a second amplifier circuit (22) configured to receive and amplify the at least one second sensor signal in order to generate at least one amplified second sensor signal; and a sensor circuit (20) configured to convert the amplified first sensor signals into the first differential signal (Dsp) with the first measured value and to convert at least one amplified second sensor signal into a measurement signal (D dir ) to convert with the second measured value, wherein the sensor circuit (20) has a signal processor (27) configured to correlate a combination of the first measured value and the second measured value with a corresponding gain setting from a plurality of gain settings, to select the corresponding gain setting from the plurality of gain settings based on the combination of the first measured value and the second measured value, and to set the selected corresponding gain setting as the gain setting of the second amplifier circuit (22). [17] Sensor device according to claim 16, wherein the corresponding gain setting is optimized for the pole wheel pitch. [18] Method for calibrating a magnetic field sensor circuit based on a pole wheel pitch of a pole wheel (11), wherein the method comprises: Generating first sensor signals by a first sensor arrangement (S) based on the detection of a changing magnetic field generated by the pole wheel (11), wherein the first sensor signals are a first differential signal (D sp ), which defines a first measured value; Generating at least one second sensor signal by means of a second sensor arrangement (D) based on the detection of the changing magnetic field generated by the pole wheel (11), wherein the at least one second sensor signal defines a second measured value that is phase-shifted with respect to the first measured value; Amplifying the first sensor signals by means of a first amplifier circuit (21) to generate amplified first sensor signals; Amplifying the at least one second sensor signal by means of a second amplifier circuit (22) in order to generate at least one amplified second sensor signal; Converting the amplified first sensor signals into the first differential signal (D) using a sensor circuit (20). sp ) with the first measurement; Converting the at least one amplified second sensor signal by the sensor circuit (20) into a measurement signal (D) dir ) with the second measurement; Correlating a combination of the first measured value and the second measured value with a corresponding gain setting from a plurality of gain settings by the sensor circuit (20); Selecting the appropriate gain setting from the plurality of gain settings based on the combination of the first and second measured values ​​by the sensor circuit (20); and Setting the selected corresponding gain setting as the gain setting of the second amplifier by the sensor circuit (20). [19] Method according to claim 18, wherein each of the plurality of gain settings corresponds to one of a plurality of pole wheel pitches programmed in a memory of the sensor circuit (20). [20] The method of claim 18 or 19, further comprising: Determining the flywheel pitch by the sensor circuit (20) using a lookup table including determining the flywheel pitch based on the combination of the first measurement and the second measurement within the lookup table and selecting the appropriate gain setting based on the determined flywheel pitch. [21] Method according to any one of claims 18 to 20, further comprising: Selecting the appropriate gain setting by the sensor circuit (20) using a lookup table, including selecting the appropriate gain setting based on the combination of the first measurement and the second measurement within the lookup table. [22] Method according to any one of claims 18 to 21, further comprising: Selecting the appropriate gain setting by the sensor circuit (20) based on a logic circuit formalized by if-then-else statements, including selecting the appropriate gain setting based on the combination of the first measured value and the second measured value that satisfies one of the if-then-else statements. [23] Method according to any one of claims 18 to 22, further comprising: Calculating a ratio of the first measured value and the second measured value using the sensor circuit (20); Comparing the ratio with at least one threshold value by the sensor circuit (20) to generate a comparison result; and Selecting the appropriate gain setting based on the comparison result by the sensor circuit (20). [24] Method according to any one of claims 18 to 23, further comprising: Selecting the appropriate gain setting based on a ratio between the first measurement and the second measurement by the sensor circuit (20). [25] Method according to any one of claims 18 to 24, further comprising: Calculating a ratio of the first measured value and the second measured value using the sensor circuit (20); Determining a threshold range from a plurality of threshold ranges in which the ratio lies, by the sensor circuit (20); and Selecting the appropriate gain setting based on the determined threshold range by the sensor circuit (20). [26] Method according to any one of claims 18 to 25, further comprising: Calculating a ratio of the first measured value and the second measured value using the sensor circuit (20); and Selecting the appropriate gain setting based on the ratio by the sensor circuit (20).

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