Linear magnetic position sensor circuit

Abstract

The invention relates to a linear magnetic position sensor circuit comprising: at least one first sensor arranged to generate a first sensing signal indicative of a first magnetic field gradient of a first magnetic field component oriented in a first direction; at least one second sensor arranged to generate a second sensing signal indicative of a second magnetic field gradient of a second magnetic field component oriented in a second direction different from the first direction; a processing circuit arranged to calculate a gradient magnitude value based on the first sensing signal and the second sensing signal, and comprising a comparison means for comparing the magnitude value with a first predetermined value. The processing circuit is further arranged to: output a position signal based on a ratio of the first sensing signal and the second sensing signal if the amplitude value is higher than a first predetermined value; and outputting the position signal on the basis of a predetermined stored value and / or on the basis of a function of the amplitude value if the amplitude value is below the first predetermined value.

Description

Technical Field

[0001] The present invention relates generally to the field of linear magnetic position sensors and methods for determining the position of a magnet along a travel. Background Art

[0002] Position sensors are known in the art.By measuring the strength of the magnetic field generated by one or more magnets at various locations, the position or orientation of the magnet(s) relative to the sensor element can be determined.

[0003] In general, field sensors are subject to measurement errors due to external perturbing magnetic fields (also called stray fields) that are unrelated to the field desired to be measured. For example, a compass is intended to measure the earth's magnetic field, but may be affected by local magnetic field sources (such as motors or other electrical machines that generate stray magnetic fields). In contrast, magnetic sensors designed to measure changes in the magnetic field produced by a magnet may be affected by the earth's magnetic field, fields from other unrelated electrical machines, or electromagnetic interference. Therefore, stray field rejection is often an important attribute of practical field sensor designs (such as, for example, position sensors). One technique to improve immunity to stray magnetic fields is to apply differential sensing.

[0004] Figure 1 A typical setup with reduced influence of external disturbance fields employed in a linear position sensor circuit is depicted in . A magnet (20) moves along an axis indicated by a line provided with arrows at the respective ends (i.e. along the x-axis). The distance the magnet can move is called the stroke. The determination of the position of the magnet is based on the magnetic field gradient or difference, which allows reducing the influence of external disturbance magnetic fields (stray fields). For example, differential sensing is applied: the magnetic field is measured at two sensing points. The sensors at the two points detect magnetic fields at different positions. The first point measures the magnetic field components Bx1 and Bz1, and the second measuring point produces magnetic field components Bx2 and Bz2. The difference between the outputs of the two sensing elements can then be calculated in the processing circuit of the sensor circuit as ΔBx=Bx1-Bx2 and ΔBz=Bz1-Bz2, which reduces the influence of constant stray fields. ΔBx and ΔBz vary with the position of the magnet. Based on the values ​​of ΔBx and ΔBz, an indication of the position of the magnet can be derived, for example via calculation of the expression atan(ΔBx / ΔBz), which yields an angle that depends on the travel (displacement in the x-direction).

[0005] Figure 2 Shows Figure 1 The typical behavior of the sensor circuit depicted in FIG. Figure 1 The displacement changes ΔBx and ΔBz in the x-direction. Figure 2The resulting angle is further shown showing jumps modulo 2π caused by the differential nature of the measurement.Thus, in these prior art solutions the displacement of the magnet must be limited to avoid jumps in the resulting angle beyond which the position of the magnet cannot be unambiguously derived.

[0006] Therefore, there is a need for a linear magnetic position sensor circuit in which the above-mentioned limitations are mitigated or overcome. Summary of the invention

[0007] It is an object of embodiments of the present invention to provide a linear magnetic position sensor circuit with an improved output range. It is a further object to provide a method of determining the position of a magnet using such a linear magnetic position sensor circuit.

[0008] The above mentioned objects are achieved by the solution according to the invention.

[0009] In a first aspect, the present invention relates to a linear magnetic position sensor circuit comprising: at least one first sensor arranged to generate a first sensing signal indicative of a first magnetic field gradient of a first magnetic field component oriented in a first direction; at least one second sensor arranged to generate a second sensing signal indicative of a second magnetic field gradient of a second magnetic field component oriented in a second direction different from the first direction; A processing circuit is arranged for calculating a gradient amplitude value based on the first sensing signal and the second sensing signal and comprises a comparing means for comparing the gradient amplitude value with a first predetermined value. The processing circuit is further arranged to: output a position signal based on a ratio of the first sensing signal to the second sensing signal when the gradient amplitude value is higher than a first predetermined value; and to output a position signal based on a predetermined stored value and / or based on a function of the gradient amplitude value when the gradient amplitude value is lower than the first predetermined value.

[0010] The proposed solution does allow a longer output range. This is achieved by providing an output position signal based on a comparison of the gradient amplitude with a preset threshold value. More precisely, if the gradient amplitude is below a first predetermined threshold value, a predetermined position signal is output based on a stored value and / or based on a function of the gradient amplitude. In case the gradient amplitude value is above the threshold value, a position signal is output based on the ratio of the two sensed signals. In the latter case, the output position signal actually corresponds to the position signal output in a sensor circuit known in the prior art. The extended output range is certainly a substantial advantage of embodiments of the present invention. It should be noted that this is achieved while still maintaining a good stray field immunity.

[0011] In a preferred embodiment, the processing circuit is arranged for comparing the gradient amplitude value with a second predetermined value and for outputting a fault signal if the gradient amplitude value is below the second predetermined value.

[0012] In an advantageous embodiment, the first sensor is a first pair of magnetic field sensing elements spaced apart from each other and sensitive to a first magnetic field component, and the first sensing signal is derived from the difference between the sensing elements of the first pair. In such an embodiment, the second sensor is a second pair of magnetic field sensing elements spaced apart from each other and sensitive to a second magnetic field component, and the second sensing signal is derived from the difference between the sensing elements of the second pair. In a preferred embodiment, a Hall sensor is employed.

[0013] In some embodiments, the predetermined value or function of said gradient magnitude value is stored in a memory of the processing circuit.

[0014] In some embodiments, the predetermined stored value is a constant value.

[0015] Advantageously, the function of the gradient magnitude value is a function of the gradient magnitude value, such as a linear or nonlinear function. In one embodiment, the function may be a polynomial function. Alternatively, the function may be implemented as a lookup table.

[0016] In a preferred embodiment, the first direction and the second direction are substantially perpendicular to each other.

[0017] In another embodiment, the function of the gradient magnitude value also depends on the gradient angle.

[0018] In one aspect, the invention relates to an integrated circuit comprising a linear magnetic position sensor circuit as described above.

[0019] In another aspect, the invention relates to a system comprising a linear magnetic position sensor circuit and a magnet as described above. The magnet may be, for example, a two-pole magnet. In a preferred embodiment, there is only one sensor circuit and therefore a single substrate along the path over which the magnet moves.

[0020] In one embodiment, the magnet is movable along a linear path, and first and second sensing signals indicative of first and second magnetic field gradients, respectively, are measured in a direction parallel to the linear path.

[0021] In one embodiment, the magnet is movable along a linear path between a first end position and a second end position, wherein the first end position is located at a position where the gradient field amplitude generated by the magnet is higher than a first predetermined value. In other words, the movement of the magnet is blocked at the first end position even if the gradient field amplitude is still higher than the first threshold level. The second end position may be located at a position where the magnetic field generated by the magnet is higher than a second predetermined value, so that no fault signal is generated.

[0022] In yet another aspect, the present invention relates to a method for determining the position of a magnet using a linear magnetic position sensor circuit as described above. The method comprises: obtaining a first sensing signal from a first magnetic field gradient sensor, the first sensing signal indicating a first magnetic field gradient of a first magnetic field component oriented in a first direction, and obtaining a second sensing signal from a second magnetic field gradient sensor, the second sensing signal indicating a second magnetic field gradient of a second magnetic field component oriented in a second direction different from the first direction; calculating a gradient amplitude value based on the first sensing signal and the second sensing signal; comparing the gradient amplitude value with a first predetermined value; If the gradient amplitude value is higher than a first predetermined value, a position signal is output based on a ratio of the first sensing signal to the second sensing signal, and if the gradient amplitude value is lower than the first predetermined value, a position signal is output based on a predetermined stored value and / or a function based on the gradient amplitude value.

[0023] For the purpose of summarizing the present invention and the advantages achieved relative to the prior art, certain objects and advantages of the present invention have been described above in this document. Of course, it should be understood that not all such objects or advantages may be achieved according to any particular embodiment of the present invention. Thus, for example, those skilled in the art will recognize that the present invention can be embodied or performed in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0024] The above and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. Description of the drawings

[0025] The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout the various drawings.

[0026] Figure 1 The figure shows a linear magnetic position sensor circuit known in the prior art.

[0027] Figure 2 The diagram shows Figure 1The behavior of the sensor circuit.

[0028] Figure 3 The figure shows a general embodiment of a linear magnetic position sensor circuit according to the present invention.

[0029] Figure 4 The figure shows a possible practical implementation of the linear magnetic position sensor circuit of the present invention.

[0030] Figure 5 The diagram shows a comparison with a predetermined value and the subsequent selection of a position signal to be output.

[0031] Figure 6 The diagram shows Figure 5 alternative.

[0032] Figure 7 The figures show an embodiment in which the movement of the magnets is mechanically blocked at the ends.

[0033] Figure 8 The figure shows a flow chart of a method according to the invention for determining the position of a magnet. DETAILED DESCRIPTION

[0034] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0035] Furthermore, the terms first, second, etc. in the specification and in the claims are used to distinguish between similar elements and are not necessarily used to describe a sequence in time, space, in ranking, or in any other manner. It should be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in a sequence different from that described or illustrated herein.

[0036] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Thus, the term should be interpreted as specifying the presence of the stated features, integers, steps or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of component A and component B. It means that for the present invention, the only relevant components of the device are A and B.

[0037] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may do so. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner as would be apparent to one of ordinary skill in the art from this disclosure.

[0038] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the inventive aspects lie in fewer features than all of the features of a single preceding disclosed embodiment. Thus, the claims appended to the specific embodiments are hereby expressly incorporated into the specific embodiments, with each claim itself representing a separate embodiment of the invention.

[0039] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in other embodiments, as those skilled in the art will appreciate, combinations of features of different embodiments are intended to fall within the scope of the present invention and form different embodiments. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0040] It should be noted that the use of a particular term in describing certain features or aspects of the present invention should not be taken as implying that the term is redefined herein to be limited to including any specific characteristics of the feature or aspect of the present invention with which the term is associated.

[0041] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques are not shown in detail to avoid obscuring the understanding of this specification.

[0042] In a first aspect, the invention proposes a linear magnetic position sensor circuit which provides improved performance with respect to solutions known in the prior art.

[0043] Consider and Figure 1The magnet (20) can move a maximum distance along the x-axis, which is called the stroke. Figure 3 A block diagram of an embodiment of a linear magnetic position sensor circuit according to the present invention is shown in . The magnetic field is measured using a first magnetic field gradient sensor (101) and a second magnetic field gradient sensor (102). The sensors detect different magnetic field gradients. The first sensor generates a first sensing signal indicating a first magnetic field gradient of a first magnetic field component oriented in a first direction. The second sensor generates a second sensing signal indicating a second magnetic field gradient of a second magnetic field component oriented in a second direction different from the first direction. In some embodiments, there may be more than one first sensor and / or more than one second sensor. In a preferred embodiment, the first direction and the second direction are substantially perpendicular. The first direction is, for example, Figure 1 The x direction is parallel to the substrate surface, and the second direction is Figure 1 The two sensing signals dBx / dx and dBz / dx are fed to a processing circuit (3) of the position sensor circuit. In a preferred embodiment, the first magnetic field gradient and the second magnetic field gradient are measured in the same direction (dx), for example in the travel direction (x direction), but this is not strictly required. The first magnetic field gradient sensor and the second magnetic field gradient sensor can be implemented as transducers that are inherently sensitive to magnetic field gradients, for example as micro-electromechanical (MEMS) gradiometers.

[0044] In some embodiments, the processing circuit (3) may include an amplifier ( Figure 3 The processing circuit may further include an analog-to-digital conversion device (not shown) for converting the received signal into a digital representation. The analog-to-digital conversion may be performed at different locations in the signal processing chain, for example before processing the difference or after processing the difference. The difference may be processed in the analog domain or in the digital domain. Figure 3 In the embodiment illustrated in FIG. 3 , the amplitude (31) and phase (32) of the received sensing signal are obtained. Based on the amplitudes of the two sensing signals, a gradient amplitude value is calculated in the processing circuit. In a preferred embodiment, the gradient amplitude value is the sum of the squares of the amplitudes of the first sensing signal and the second sensing signal, and is therefore dBx 2 +dBz 2 In other embodiments, the square root of the sum of squares may be used. The derived gradient magnitude value is then compared to a first predetermined value by a comparator (33). The processing circuit then makes a decision based on the comparison of the position signal to be output. Figure 3, represented by an output selection block (35). If the gradient amplitude value is above a first predetermined value, the output position signal is based on the ratio of the first sensed signal and the second sensed signal. The output position signal may be an analog signal (e.g., a percentage of the supply voltage, or a PWM signal) or a digital signal (e.g., transmitted via a standard digital protocol such as SENT, SPC, SPI, etc.). In a preferred embodiment, the output position signal is derived from atan (dBx / dBz) and optionally includes further linearization. However, alternatives are available. For example, a lookup table may be used to derive the output position signal from the ratio of the gradient. Otherwise, if the gradient amplitude value is below a first predetermined value, the position signal is output based on a predetermined stored value and / or a function based on the gradient amplitude value. Preferably, the output signal is then based only on the predetermined stored value and / or a function based on the gradient amplitude value, and nothing else. In some embodiments, the predetermined value and / or the function is stored in a memory (34), which may advantageously be part of the processing circuit. The memory is then connected to the output selection block to provide the stored value or function to be used. The function of the gradient amplitude value is, for example, a linear function of the amplitude, or a nonlinear function. In other embodiments, the function is a polynomial function. Alternatively, a lookup table can be used. The function or lookup table can also be stored in a memory.

[0045] exist Figure 4 It is shown in Figure 3 A practical implementation of the solution. A differential configuration is applied, whereby sensors (101, 102) at two measuring points detect magnetic fields at different locations. The first sensor measures magnetic field components Bx1 and Bz1, and the sensor at the second measuring point generates magnetic field components Bx2 and Bz2. In a preferred embodiment, the sensors are Hall sensors. Figure 4 In the embodiment shown in , the difference (37) between the outputs of the two sensing elements is calculated in the processing circuit of the sensor circuit as ΔBx=Bx1-Bx2 and ΔBz=Bz1-Bz2. ΔBx and ΔBz vary as the position of the magnet changes. In one embodiment, the difference can be determined after digitization of the gradient signal. In another embodiment, the difference can be determined outside the processing circuit before digitization, for example using a switch matrix and by combining the sensing signals in the analog domain. Based on the values ​​of ΔBx and ΔBz, the gradient amplitude value (e.g., ΔBx) is calculated. 2 +ΔBz 2 ), and after comparing this value with a predetermined threshold or a function of a threshold, an indication of the position of the magnet is derived as described above, depending on the result of the comparison.

[0046] Figure 5More particularly, the selection of the output signal depending on the comparison result is illustrated. In the left part of the drawing, the gradient magnitude value is higher than the threshold level TH2, and (e.g., in the linear range) the position signal is output. As can be seen from the figure, when the gradient magnitude value (in this particular example, dBx 2 +dBz 2 ) drops below the threshold TH2, the position signal has a constant value, which in some embodiments can be stored in a memory provided in the processing circuit. As already mentioned, in other embodiments, a value can be assigned to the position signal based on a function of the gradient magnitude value or a value derived from a look-up table. In some embodiments, the function can be not only a function of the gradient magnitude but also a function of the gradient phase.

[0047] An extended output range is obtained by providing a comparison of a value related to the gradient magnitude with a threshold, and by providing an appropriate position signal when the gradient magnitude value drops below the threshold. This is the main asset of the position sensor circuit according to the present invention.

[0048] Figure 6 Another possible scenario for deriving the position signal is provided. In Figure 6 , the position signal output in the case where the gradient magnitude value is below the threshold TH2 is a function not only of the gradient magnitude value but also of the phase (angle) of the gradient. Thus, the condition of the angle value is used in combination with the magnitude value of the gradient in order to determine the position and set the output position signal (e.g., clamped at a high level or a low level as shown in Figure 6 , or output according to the position of the magnitude and the angle). In the particular case illustrated in Figure 6 , also on the left side, i.e., at the lower end of the linear range, the position signal is output based on a predetermined stored value and / or a function of the gradient magnitude value and (possibly) a function of the gradient phase. Further note that in Figure 6 , in contrast to Figure 5 , the full linear range is utilized.

[0049] Figure 5 And Figure 6 Further illustrate that in some embodiments, a second predetermined value (indicated as TH1 in the drawing, where TH1 < TH2) is optionally provided. This second predetermined value can also be stored in the memory of the processing circuit. Then, the processing circuit compares the gradient magnitude value with the second threshold, and if the gradient magnitude value drops below TH1, a fault signal is output.

[0050] In an advantageous embodiment, the first sensor is implemented as a pair of magnetic field sensing elements spaced apart from each other and arranged to sense a first magnetic field component. A first sensing signal can then be derived from the difference between the sensing elements of the pair. Then, the second sensor is another pair of magnetic field sensing elements spaced apart from each other and sensitive to the second magnetic field component. A second sensing signal can then be derived from the difference between the sensing elements of the other pair. In some embodiments, the distance between the sensing elements in the two pairs of sensing elements is less than the size of the magnet extending in the stroke direction (e.g., along the x-direction), or less than 50% of the size of the magnet extending in the stroke direction, or less than 25% of the size of the magnet extending in the stroke direction. For example, the spacing between the sensing elements is less than 100%, or 50%, or 25% of the length of the magnet in the stroke direction.

[0051] In one aspect, the invention relates to an integrated circuit comprising a linear magnetic position sensor circuit as described above. Preferably, a single integrated circuit is used along the travel.

[0052] In another aspect, the present invention relates to a system comprising a linear magnetic position sensor circuit as described above, and a magnet (e.g., a two-pole magnet), but not limited thereto. The magnetization direction of the magnet may be orthogonal to the travel direction, or parallel to the travel direction. For example, the magnetization direction of the magnet may be parallel to a plane defined in the top surface of the integrated circuit, or perpendicular to a plane defined in the top surface of the integrated circuit.

[0053] In a preferred embodiment, the magnet is movable along a linear path between a first end position and a second end position. The first end position is located at a position where the amplitude of the gradient field generated by the magnet is above a first predetermined value. Figure 7 An illustration is provided in . In this example, the output of the integrated circuit is defined as a percentage of the supply voltage, also known as a ratiometric output. The linear position of the magnet is reported as a signal proportional to the supply voltage of the integrated circuit. As shown in Figure 7 As can be observed in the figure, the transfer function is not linear in the central part of the stroke, but is still strictly monotonic and each position can be unambiguously derived from the output signal. In this figure, one end of the magnet stroke is mechanically blocked at a position PA, where the magnetic field strength is above a predetermined value TH2. In this case, the magnet cannot even reach the area outside PA, where the gradient amplitude value falls below the first predetermined value. As shown in the figure, when the gradient amplitude value drops below TH2, a position signal with a clamped output value is used. This allows to obtain an extended output range.

[0054] Additionally and optionally, the gradient amplitude is compared with a second predetermined value ( Figure 7The error signal is compared with TH1 in , and an error signal is output when the gradient amplitude drops below a second predetermined value (indicating that the magnet may be damaged or out of the sensing range, for example). The error signal may be a digital signal (e.g., Figure 7 In some embodiments of the invention, position PB is mechanically blocked at a position where the gradient amplitude is above a second predetermined value, so that TH1 is not crossed in the absence of a failure in the system.

[0055] In one aspect, the invention relates to a method for determining the position of a magnet by means of a linear magnetic position sensor circuit as described above. Figure 8 A flow chart illustrating an embodiment of the proposed method is provided.

[0056] A first signal is sensed, the first signal indicating a first gradient of a first magnetic field component oriented in a first direction. In one embodiment, the signal may be dBx / dx. A second signal is sensed, the second signal indicating a second gradient of a second magnetic field component oriented in a second direction. In one embodiment, the signal may be dBz / dx.

[0057] Next, a gradient amplitude value may be calculated based on the first signal and the second signal. In a preferred embodiment, the calculation involves the sum of squares of the first signal and the second signal. The gradient amplitude value is then compared to a first predetermined value. In the case where the gradient amplitude value is higher than the first predetermined value, an output position signal is obtained based on a ratio of the first sensing signal and the second sensing signal. Conversely, if the gradient amplitude value is less than the first predetermined value, the output position signal is based on a stored predetermined value.

[0058] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary, rather than restrictive. The foregoing description describes certain embodiments of the present invention in detail. However, it will be appreciated that no matter how detailed the foregoing description appears in text, the present invention can be practiced in many ways. The present invention is not limited to the disclosed embodiments.

[0059] By studying the drawings, the present disclosure and the appended claims, those skilled in the art may understand and implement other variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude pluralities. A single processor or other unit may perform the functions of several items recited in the claims. The mere fact that certain measures are stated in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. The computer program may be stored / distributed on a suitable medium (such as an optical storage medium or solid-state medium supplied together with or as part of other hardware), but may also be distributed in other forms (such as via the Internet or other wired or wireless telecommunications systems). Any reference numerals in the claims should not be interpreted as limiting the scope.

Claims

1. A linear magnetic position sensor circuit, comprising: at least one first sensor arranged to generate a first sensing signal indicative of a first magnetic field gradient of a first magnetic field component oriented in a first direction; at least one second sensor arranged to generate a second sensing signal indicative of a second magnetic field gradient of a second magnetic field component oriented in a second direction different from the first direction; a processing circuit arranged for calculating a gradient amplitude value based on the first sensing signal and the second sensing signal and comprising comparison means for comparing the gradient amplitude value with a first predetermined value; Characterized in that the processing circuit is further arranged to: output a position signal based on a ratio of the first sensing signal to the second sensing signal when the gradient amplitude value is higher than the first predetermined value; And is used for outputting a position signal based on a predetermined stored value and / or based on a function of the gradient amplitude value when the gradient amplitude value is lower than the first predetermined value.

2. The linear magnetic position sensor circuit according to claim 1, characterized in that The processing circuit is arranged for comparing the gradient amplitude value with a second predetermined value and for outputting a fault signal if the gradient amplitude value is below the second predetermined value.

3. The linear magnetic position sensor circuit according to claim 1, characterized in that: The first sensor is a first pair of magnetic field sensing elements spaced apart from each other and sensitive to the first magnetic field component, and the first sensing signal is derived from a difference between the sensing elements in the first pair, and Wherein the second sensor is a second pair of magnetic field sensing elements spaced apart from each other and sensitive to the second magnetic field component, and the second sensing signal is derived from a difference between the sensing elements in the second pair.

4. The linear magnetic position sensor circuit according to claim 1, characterized in that: The predetermined storage value is a constant value.

5. The linear magnetic position sensor circuit according to claim 1, characterized in that: The function of the gradient magnitude values ​​is a linear function of the gradient magnitude values, or a lookup table.

6. The linear magnetic position sensor circuit of claim 1, further comprising a memory for storing said predetermined stored value and / or said function of said gradient amplitude value.

7. The linear magnetic position sensor circuit according to claim 1, characterized in that: The first direction and the second direction are substantially perpendicular to each other.

8. The linear magnetic position sensor circuit according to claim 1, characterized in that: The function of the gradient magnitude value also depends on the gradient angle.

9. An integrated circuit comprising the linear magnetic position sensor circuit of claim 1.

10. A system comprising the linear magnetic position sensor circuit of claim 1, and a magnet.

11. The system according to claim 10, characterized in that The magnet is movable along a linear path, and wherein the first sensing signal and the second sensing signal indicative of the first magnetic field gradient and the second magnetic field gradient, respectively, are measured in a direction parallel to the linear path.

12. The system according to claim 10, characterized in that The magnet is movable along a linear path between a first end position and a second end position, wherein the first end position is located at a position where the amplitude of the gradient field generated by the magnet is above the first predetermined value.

13. The system of claim 12, wherein: The second end position is located at a position where the magnetic field generated by the magnet is higher than the second predetermined value.

14. The system according to claim 10, characterized in that Implemented as part of a braking system.

15. A method for determining the position of a magnet using a linear magnetic position sensor circuit, comprising: obtaining a first sensing signal from a first magnetic field gradient sensor, the first sensing signal indicating a first magnetic field gradient of a first magnetic field component oriented in a first direction, and obtaining a second sensing signal from a second magnetic field gradient sensor, the second sensing signal indicating a second magnetic field gradient of a second magnetic field component oriented in a second direction different from the first direction; calculating a gradient amplitude value based on the first sensing signal and the second sensing signal; Comparing the gradient amplitude value with a first predetermined value; When the gradient amplitude value is higher than the first predetermined value, a position signal is output based on the ratio of the first sensing signal to the second sensing signal; and when the gradient amplitude value is lower than the first predetermined value, a position signal is output based on a predetermined stored value and / or based on a function of the gradient amplitude value.

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