Magnetic field sensing device

Abstract

A magnetic field sensing device is provided. The magnetic field sensing device includes a magneto-resistive sensor, a Hall sensor, and an operation circuit. The magneto-resistive sensor senses a magnetic field to provide a magneto-resistive sensing value. The Hall sensor senses the magnetic field to provide a Hall sensing value. The operation circuit provides a weight value according to the magneto-resistive sensing value, and generates a first operation value according to the weight value and the Hall sensing value, and generates a second operation value according to the weight value and the magneto-resistive sensing value. The operation circuit operates the first operation value, the second operation value, and the magneto-resistive sensing value to generate an output signal having an output value. The output value is related to a strength of the magnetic field.

Description

Technical Field

[0001] This invention relates to a sensing device, and more particularly to a magnetic field sensing device. Background Technology

[0002] Magnetic field sensors can be mainly divided into two types: magnetoresistive sensors and Hall sensors. Generally, magnetoresistive sensors can achieve a high signal-to-noise ratio (SNR) under low magnetic field strength. However, magnetoresistive sensors reach sensing saturation under high magnetic field strength. Therefore, the maximum magnetoresistive sensing value of a magnetoresistive sensor is limited. Hall sensors, on the other hand, do not have a limited Hall sensing value. However, Hall sensors can have a lower SNR under low magnetic field strength. Therefore, how to provide a magnetic field sensing device that is suitable for a wide range of magnetic field strengths and has a high SNR is one of the research focuses of those skilled in the art. Summary of the Invention

[0003] The present invention provides a magnetic field sensing device that is applicable to a wide range of magnetic field strengths and has a high signal-to-noise ratio.

[0004] The magnetic field sensing device of the present invention includes a magnetoresistive sensor, a Hall sensor, and a computational circuit. The magnetoresistive sensor senses the magnetic field to provide a magnetoresistive sensing value. The Hall sensor senses the magnetic field to provide a Hall sensing value. The computational circuit is coupled to the magnetoresistive sensor and the Hall sensor. The computational circuit provides a weight value based on the magnetoresistive sensing value, generates a first computational value based on the weight value and the Hall sensing value, and generates a second computational value based on the weight value and the magnetoresistive sensing value. The computational circuit performs calculations on the first computational value, the second computational value, and the magnetoresistive sensing value to generate an output signal having an output value. The output value is related to the strength of the magnetic field.

[0005] Based on the above, the arithmetic circuit generates a first calculated value based on a weighted value and a Hall effect sensor value, and generates a second calculated value based on a weighted value and a magnetoresistive sensor value. The arithmetic circuit performs calculations on the first calculated value, the second calculated value, and the magnetoresistive sensor value to generate an output signal with an output value. Therefore, the arithmetic circuit performs weighted calculations on the Hall effect sensor value and the magnetoresistive sensor value to generate an output value related to the strength of the magnetic field. In this way, the magnetic field sensing device can be applied to a wide range of magnetic field strengths and has the advantage of a high signal-to-noise ratio.

[0006] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a magnetic field sensing device according to the first embodiment of the present invention;

[0008] Figure 2 This is a schematic diagram illustrating the relationship between the Hall sensing value, the magnetoresistive sensing value, and the output value according to an embodiment of the present invention;

[0009] Figure 3 This is a schematic diagram illustrating the relationship between signal-to-noise ratio and magnetic field strength according to an embodiment of the present invention;

[0010] Figure 4 This is a schematic diagram of a magnetic field sensing device according to a second embodiment of the present invention;

[0011] Figure 5 This is a circuit diagram of an operational circuit according to an embodiment of the present invention;

[0012] Figure 6 This is a circuit diagram of a multiplier according to an embodiment of the present invention.

[0013] Explanation of reference numerals in the attached figures

[0014] 100, 200: Magnetic field sensing device

[0015] 110, 210: Magnetoresistive sensors

[0016] 120, 220: Hall effect sensors

[0017] 130, 230: Operational circuits

[0018] 231, 331: Weighted signal generator

[0019] 232, 233, 332, 333: Multiplication circuits

[0020] 234, 334: Adders

[0021] 3312: Triangular wave signal generator

[0022] A HL Hall sensor value

[0023] A MR Magnetoresistive sensing value

[0024] AOV1: First operand

[0025] AOV2: Second operand

[0026] -A OUT Output value

[0027] CF: Capacitor

[0028] CP: Comparator

[0029] HL+: First sensing value

[0030] HL-: First reference value

[0031] M: Magnetic field strength value

[0032] M1: Strength value

[0033] MPX1, MPX2: Multipliers

[0034] MR+: Second sensing value

[0035] MR-: Second reference value

[0036] OA1, OA2, OA3: Operational amplifiers

[0037] SOUT: Output signal

[0038] R1, R2, R3, RS: Resistors

[0039] RF1, RF2, RF3: Magnetic field strength range

[0040] SNR: Signal-to-noise ratio

[0041] SR: Reference triangular wave signal

[0042] SW: Weighted Signal

[0043] SW1, SW2, SW3, SW4: Switches

[0044] U1~U8: Sensing components

[0045] V: Voltage value

[0046] VH: Reference voltage source

[0047] W: Weight value Detailed Implementation

[0048] Some embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Component symbols used in the following description, when appearing in different drawings, are considered to be the same or similar components. These embodiments are only a part of the present invention and do not disclose all possible implementations of the invention. More precisely, these embodiments are merely examples within the scope of the present invention's patent application.

[0049] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a magnetic field sensing device according to a first embodiment of the present invention. In this embodiment, the magnetic field sensing device 100 includes a magnetoresistive sensor 110, a Hall sensor 120, and a processing circuit 130. The magnetoresistive sensor 110 senses a magnetic field (not shown) to provide a magnetoresistive sensing value A.MR The magnetoresistive sensor 110 can be implemented using various types of magnetoresistive sensors well known to those skilled in the art. For example, the magnetoresistive sensor is one of anisotropic magnetoresistive (AMR) sensors, giant magnetoresistive (GMR) sensors, and tunnel magnetoresistive (TMR) sensors, but the invention is not limited thereto. The Hall sensor 120 senses the magnetic field to provide a Hall sensing value A. HL In this embodiment, the Hall sensor value A HL and magnetoresistive sensing value A MR These are the voltage values.

[0050] In this embodiment, the arithmetic circuit 130 is coupled to the magnetoresistive sensor 110 and the Hall sensor 120. The arithmetic circuit 130 calculates the magnetoresistive sensing value A based on the magnetoresistive sensing value A. MR To provide a weight value W, based on the weight value W and the Hall sensing value A HL To generate the first calculated value AOV1, and based on the weight value W and the magnetoresistive sensing value A MR This generates a second calculated value AOV2. The arithmetic circuit 130 processes the first calculated value AOV1, the second calculated value AOV2, and the magnetoresistive sensing value A. MR Perform the operation to produce an output value -A OUT The output signal is SOUT. In other words, the operational circuit 130 will process the magnetoresistive sensing value A. MR and Hall sensor value A HL The output value -A, related to the strength of the magnetic field, is generated by performing weighted calculations. OUT In this embodiment, the output value is -A. OUT The symbol "-" in the text indicates the output value -A. OUT The output value is negatively correlated with the strength of the magnetic field. In some embodiments, the output value may be positively correlated with the strength of the magnetic field, but this invention is not limited thereto.

[0051] It is worth mentioning that the magnetoresistive sensor 110 exhibits a high signal-to-noise ratio (SNR) under low magnetic field strength. The Hall sensing value A of the Hall sensor 120... HL Sensing saturation is difficult to achieve under high magnetic field strength. The operational circuit 130 operates based on the magnetoresistive sensing value A. MR This provides the weight value W. The arithmetic circuit 130 uses the weight value W to adjust the magnetoresistive sensing value A. MR and Hall sensor value A HL The output value -A is calculated by performing weight calculations. OUTIn this way, the magnetic field sensing device 100 can be applied to a wide range of magnetic field strengths and has the advantage of a high signal-to-noise ratio under low magnetic field strengths.

[0052] In this embodiment, the magnetoresistive sensing value A MR It is proportional to the weight value W. The arithmetic circuit 130 operates based on the magnetoresistive sensing value A. MR This provides a weight value W. The weight value W is greater than or equal to 0 and less than or equal to 1 (i.e., 0 ≦ W ≦ 1). The arithmetic circuit 130 will process the Hall sensor value A. HL And the weight value W is multiplied to produce the first operand value AOV1. Therefore, the first operand value AOV1 will be equal to "W × A HL The operational circuit 130 will process the magnetoresistive sensing value A. MR The negative value and the weight value W are multiplied to produce the second calculated value AOV2. Therefore, the second calculated value AOV2 will be equal to "-W×A". MR ".

[0053] Next, the arithmetic circuit 130 processes the first arithmetic value AOV1, the second arithmetic value AOV2, and the magnetoresistive sensing value A. MR Perform the operation to produce an output value -A OUT The output signal is SOUT. Therefore, the output value is -A. OUT It will equal "W×A" HL +(1-W)×A MR The negative value of "".

[0054] Please also refer to Figure 1 as well as Figure 2 , Figure 2 This is a schematic diagram illustrating the relationship between the Hall effect sensing value, the magnetoresistive sensing value, and the output value according to an embodiment of the present invention. In this embodiment, the magnetoresistive sensing value A... MR Hall sensor value A HL The weight value W increases with the increase of the magnetic field strength value M. When the magnetic field strength value M is low, the magnetoresistive sensing value A... MR Higher than Hall sensor value A HL Therefore, when the magnetic field strength M is less than the strength M1, the magnetoresistive sensing value A... MR The weight of A (i.e., "1-W") is relatively large, while the Hall sensing value A HL The weight (i.e., "W") is smaller. As the strength of the magnetic field increases, the magnetoresistive sensing value A... MR The weight will decrease, while the Hall sensing value A HL The weight (i.e., "W") increases. As the magnetic field strength value M increases, the output value -A... OUT It will decrease linearly based on the weight value W.

[0055] When the magnetic field strength M is greater than or equal to the strength M1, the magnetoresistive sensing value A MR The saturation value is reached (e.g., 4 volts, but this invention is not limited thereto). Magnetoresistive sensing value A MR It reaches saturation and cannot increase further with the strength of the magnetic field. The weight value W equals 1. Magnetoresistive sensing value A MR The weight is equal to 0. Hall sensor value A HL The weight is equal to 1. Therefore, the output value is -A. OUT It will equal the Hall sensor value A HL The negative value. When the magnetic field strength value M is greater than or equal to the strength value M1, the output value is -A. OUT Based on Hall sensor value A HL And it continues to decline linearly.

[0056] Please also refer to Figure 1 as well as Figure 3 , Figure 3 This is a schematic diagram illustrating the relationship between signal-to-noise ratio and magnetic field strength according to an embodiment of the present invention. This embodiment shows magnetic field strength ranges RF1, RF2, and RF3. The magnetic field strength in range RF3 is higher than that in range RF2. The magnetic field strength in range RF2 is higher than that in range RF1. In range RF1, the magnetoresistive sensing value A... MR The weight of A (i.e., "1-W") is relatively large, while the Hall sensing value A HL The weight (i.e., "W") is smaller. This is because the magnetoresistive sensing value A... MR It exhibits a high signal-to-noise ratio under magnetic field strength. Therefore, within the magnetic field strength range RF1, the signal-to-noise ratio of the output signal SOUT will be greater than that of the Hall sensor 120 (as shown by the dashed line).

[0057] Compared to the magnetic field strength range RF1, the magnetoresistive sensing value A MR The weighting will decrease within the magnetic field strength range RF2. Hall sensing value A HL The weight of M will increase. Therefore, within the magnetic field strength range RF2, the signal-to-noise ratio (SNR) of the output signal SOUT will gradually decrease as the magnetic field strength M increases. However, the SNR of the output signal SOUT is still greater than that of the Hall sensor 120 (as shown by the dashed line).

[0058] Within the magnetic field strength range RF3, the magnetoresistive sensing value A MR Saturation value reached. Magnetoresistive sensing value A MR The weight is equal to 0. Hall sensor value A HL The weight is equal to 1. Therefore, the signal-to-noise ratio of the output signal SOUT will be equal to the signal-to-noise ratio of the Hall sensor 120.

[0059] Please refer to Figure 4 , Figure 4 This is a schematic diagram of a magnetic field sensing device according to a second embodiment of the present invention. In this embodiment, the magnetic field sensing device 200 includes a magnetoresistive sensor 210, a Hall sensor 220, and a processing circuit 230. The Hall sensor 220 provides a first sensing value HL+ and a first reference value HL-. The difference between the first sensing value HL+ and the first reference value HL- is equal to the Hall sensing value A. HL The magnetoresistive sensor 210 provides a second sensed value MR+ and a second reference value MR-. The difference between the second sensed value MR+ and the second reference value MR- is equal to the magnetoresistive sensed value A. MR .

[0060] For example, magnetoresistive sensor 210 and Hall sensor 220 each have multiple magnetic field sensing components in a bridge structure. Magnetoresistive sensor 210 includes sensing components U1 to U4. Sensing components U1 to U4 are connected in a bridge structure. The connection node between sensing components U1 and U2 is coupled to a reference voltage source VH. The connection node between sensing components U3 and U4 is coupled to a reference low voltage (e.g., ground). The connection node between sensing components U2 and U4 is used to output a second sensed value MR+. The connection node between sensing components U1 and U3 is used to output a second reference value MR-. Therefore, as the magnetic field strength increases, the second sensed value MR+ increases linearly, while the second reference value MR- decreases linearly. Hall sensor 220 includes sensing components U5 to U8. Sensing components U5 to U8 are connected in a bridge structure. The connection node between sensing components U5 and U6 is coupled to a reference voltage source VH. The connection node between sensing components U7 and U8 is coupled to a reference low voltage. The connection node between sensing components U6 and U8 is used to output the first sensed value HL+. The connection node between sensing components U5 and U7 is used to output the first reference value HL-. Therefore, as the magnetic field strength increases, the first sensed value HL+ will increase linearly, while the first reference value HL- will decrease linearly.

[0061] For another example, the first reference value HL- and the second reference value MR- can be low reference values. Therefore, the first sensed value HL+ is approximately equal to the Hall sensed value A. HL The second sensing value MR+ is approximately equal to the magnetoresistive sensing value A. MR .

[0062] In this embodiment, the arithmetic circuit 230 includes a weight signal generator 231, multiplication circuits 232 and 233, and an adder 234. The weight signal generator 231 is coupled to the magnetoresistive sensor 210. The weight signal generator 231 responds to the second sensed value MR+ and generates a weight signal SW with a weight value W. In this embodiment, the weight signal SW is a pulse-width modulation (PWM) signal. The weight value W is positively correlated with the duty cycle of the weight signal SW. In this embodiment, the weight value W is set to be greater than or equal to 0 and less than or equal to 1 (i.e., 0 ≤ W ≤ 1).

[0063] For example, in a single cycle, the weighted signal SW has a positive pulse width and a duration of low voltage. The weight value W is approximately equal to the quotient of the positive pulse width divided by the duration. As another example, the weight value W is approximately equal to the duty cycle of the weighted signal SW or an offset of the duty cycle of the weighted signal SW.

[0064] Multiplication circuit 232 is coupled to Hall sensor 220 and weight signal generator 231. Multiplication circuit 232 performs a first multiplication operation based on a first sensed value HL+, a first reference value HL-, and a weight value W to generate a first calculated value. Multiplication circuit 233 is coupled to magnetoresistive sensor 210 and weight signal generator 231. Multiplication circuit 233 performs a second multiplication operation based on a second sensed value MR+, a second reference value MR-, and a weight value W to generate a second calculated value. In this embodiment, the first calculated value is equal to "W × A". HL The second calculated value will equal "-W×A". MR ".

[0065] Adder 234 is coupled to magnetoresistive sensor 210 and multiplication circuits 232 and 233. Adder 234 performs an operation on the first operand (i.e., "W×A"). HL The second operand (i.e., "-W×A") MR ") and magnetoresistive sensing value A MR Perform the operation to produce an output value -A OUT The output signal is SOUT. For example, adder 234 can be implemented by an inverting adder. Therefore, the output value is -A. OUT It will equal "W×A" HL +(1-W)×A MR The negative value of "".

[0066] Please refer to Figure 5 , Figure 5This is a circuit diagram of an arithmetic circuit according to an embodiment of the present invention. In this embodiment, the arithmetic circuit 330 includes a weight signal generator 331, multiplication circuits 332 and 333, and an adder 334. The weight signal generator 331 includes a comparator CP. The non-inverting input of the comparator CP receives the second sensed value MR+. The inverting input of the comparator CP receives a reference triangular wave signal SR. The comparator CP compares the voltage values ​​of the second sensed value MR+ and the reference triangular wave signal SR to generate the weight signal SW.

[0067] In this embodiment, the higher the second sensing value MR+, the wider the positive pulse width of the weighted signal SW. Therefore, the duty cycle of the weighted signal SW is longer, and the weight value W is also higher. Conversely, the lower the second sensing value MR+, the narrower the positive pulse width of the weighted signal SW. Therefore, the duty cycle of the weighted signal SW is shorter, and the weight value W is also lower.

[0068] In this embodiment, the weight signal generator 331 further includes a triangular wave signal generator 3312. The triangular wave signal generator 3312 references the triangular wave signal SR to the inverting input of the comparator CP. In some embodiments, the weight signal generator 331 may be disposed outside the weight signal generator 331 or outside the arithmetic circuit 330, and the present invention is not limited to the placement of the triangular wave signal generator 3312.

[0069] In this embodiment, the multiplication circuit 332 includes a multiplier MPX1. The positive input terminal of the multiplier MPX1 receives the first sensed value HL+. The negative input terminal of the multiplier MPX1 receives the first reference value HL-. The control terminal of the multiplier MPX1 receives a weighting signal SW. The output terminal of the multiplier MPX1 is used to output the first calculated value (i.e., "W×A"). HL In this embodiment, the first calculated value is equal to the product of the weight value W and the first sensed value HL+.

[0070] Furthermore, to maintain or improve the signal fan-out capability of the multiplication circuit 332, the multiplication circuit 332 may include a buffer generated by the operational amplifier OA1. In this embodiment, the non-inverting input of the operational amplifier OA1 is coupled to the output of the multiplier MPX1 to receive the first operational value. The inverting input of the operational amplifier OA1 is coupled to the output of the operational amplifier OA1. Therefore, the buffer may be a unity-gain buffer.

[0071] In this embodiment, the multiplication circuit 333 includes a multiplier MPX2. The positive input terminal of multiplier MPX2 receives a second reference value MR-. The negative input terminal of multiplier MPX2 receives a second sensed value MR+. The control terminal of multiplier MPX2 receives a weighting signal SW. The output terminal of multiplier MPX1 is used to output a second operational value (i.e., "-W×A"). MR It should be noted that the positive input of multiplier MPX2 receives the second reference value MR-. The negative input of multiplier MPX2 receives the second sensed value MR+. Therefore, multiplier MPX2 is equivalent to receiving the magnetoresistive sensed value A. MR The negative value of the weight value. In this embodiment, the second calculated value is equal to the product of the weight value and the negative value of the second sensed value.

[0072] Furthermore, to maintain or improve the signal fan-out capability of the multiplication circuit 333, the multiplication circuit 333 may include a buffer generated by the operational amplifier OA2. In this embodiment, the non-inverting input of the operational amplifier OA2 is coupled to the output of the multiplier MPX2 to receive the second operational value. The inverting input of the operational amplifier OA2 is coupled to the output of the operational amplifier OA2.

[0073] In this embodiment, adder 334 includes operational amplifier OA3 and resistors R1, R2, R3, and RS. The non-inverting input of operational amplifier OA3 receives a reference voltage Vcom. The output of operational amplifier OA3 is used to output the output signal SOUT. Resistor R1 is coupled between multiplication circuit 332 and the inverting input of operational amplifier OA3. Resistor R2 is coupled between multiplication circuit 333 and the inverting input of operational amplifier OA3. The first terminal of resistor R3 receives a second sensed value MR+. The second terminal of resistor R3 is coupled to the inverting input of operational amplifier OA3. Resistor RS is coupled between the inverting input of operational amplifier OA3 and its output. Therefore, the inverting input of operational amplifier OA3 receives a first operational value from multiplication circuit 332 through resistor R1, a second operational value from multiplication circuit 333 through resistor R2, and a second sensed value MR+ from a magnetoresistive sensor through resistor R3.

[0074] In this embodiment, the resistance values ​​of resistors R1, R2, R3, and RS are designed to be the same. Therefore, adder 334 can perform operations on the first calculated value (i.e., "W×A"). HL The second operand (i.e., "-W×A") MR ") and the second sensing value MR+ (i.e., "A") MR Perform an inverse addition operation to produce the output value -A. OUT That is, the output value is -A.OUT Equals "W×A" HL +(1-W)×A MR The negative value of "".

[0075] In some embodiments, the resistance values ​​of resistor R1, resistor R2, resistor R3, and resistor RS can be adjusted to change the output value -A. OUT .

[0076] In this embodiment, adder 334 also includes capacitor CF. Capacitor CF is coupled between the inverting input and output of operational amplifier OA3. Capacitor CF and resistor RS form a filter. The capacitance value of capacitor CF determines the filter's frequency bandwidth.

[0077] It should also be noted that in this embodiment, the arithmetic circuit 330 does not need to perform analog-to-digital conversion to output the value -A. OUT The calculation is performed. In this way, the calculation circuit 330 can generate an output value -A in real time based on the first sensed value HL+, the first reference value HL-, the second sensed value MR+, and the second reference value MR-. OUT .

[0078] Please refer to Figure 6 , Figure 6 This is a circuit diagram of a multiplier according to an embodiment of the present invention. Figure 6 As shown Figure 5 The circuit diagrams of multipliers MPX1 and MPX2 are shown below. In this embodiment, multiplier MPX1 includes switches SW1 and SW2. The first terminal of switch SW1 is coupled to the positive input terminal of multiplier MPX1. The first terminal of switch SW1 receives a first sensed value HL+. The second terminal of switch SW1 is coupled to the output terminal of multiplier MPX1. The control terminal of switch SW1 receives the weight signal SW. The first terminal of switch SW2 is coupled to the negative input terminal of multiplier MPX1. The first terminal of switch SW2 receives a first reference value HL-. The second terminal of switch SW2 is coupled to the output terminal of multiplier MPX1. The control terminal of switch SW2 receives the weight signal SW.

[0079] Multiplier MPX2 includes switches SW3 and SW4. The first terminal of switch SW3 is coupled to the positive input terminal of multiplier MPX2. The first terminal of switch SW3 receives a second reference value MR-. The second terminal of switch SW3 is coupled to the output terminal of multiplier MPX2. The control terminal of switch SW3 receives the weighting signal SW. The first terminal of switch SW4 is coupled to the negative input terminal of multiplier MPX2. The first terminal of switch SW4 receives a second sensed value MR+. The second terminal of switch SW4 is coupled to the output terminal of multiplier MPX2. The control terminal of switch SW4 receives the weighting signal SW.

[0080] In multiplier MPX1, switch SW1 is turned on in response to a positive pulse of weight signal SW and turned off in response to a low voltage level of weight signal SW. Conversely, switch SW2 is turned off in response to a positive pulse of weight signal SW and turned on in response to a low voltage level of weight signal SW. Multiplier MPX1 determines the first operational value based on the ratio of the first sensed value HL+ through multiplier MPX1. In other words, the output of multiplier MPX1 is determined based on the duty cycle of weight signal SW (i.e., weight value W) and Hall sensed value A. HL To output the first operation value (i.e., "W×A") HL (”).

[0081] In multiplier MPX2, switch SW2 is turned on in response to a positive pulse of the weight signal SW and turned off in response to a low voltage level of the weight signal SW. Conversely, switch SW4 is turned off in response to a positive pulse of the weight signal SW and turned on in response to a low voltage level of the weight signal SW. Multiplier MPX2 determines the second operational value based on the ratio of the second sensed value MR+ through multiplier MPX2. In other words, the output of multiplier MPX2 is determined based on the duty cycle of the weight signal SW (i.e., the weight value W) and the magnetoresistive sensed value A. MR The negative value is used to output the second operation value (i.e., "-W×A"). MR (”).

[0082] In summary, magnetoresistive sensors exhibit a high signal-to-noise ratio under low magnetic field strength. Hall effect sensors, on the other hand, are less prone to saturation under high magnetic field strength. The computational circuit provides weighting values ​​based on the magnetoresistive sensing values. The circuit then performs weighted calculations on the Hall and magnetoresistive sensing values ​​to generate an output value related to the magnetic field strength. As a result, the magnetic field sensing device is applicable to a wide range of magnetic field strengths and offers the advantage of a high signal-to-noise ratio.

[0083] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended claims.

Claims

1. A magnetic field sensing device, characterized in that, The magnetic field sensing device includes: A magnetoresistive sensor, configured to sense a magnetic field to provide a magnetoresistive sensing value; A Hall sensor, configured to sense the magnetic field to provide a Hall sensing value; and An arithmetic circuit, coupled to the magnetoresistive sensor and the Hall sensor, is configured to provide a weight value based on the magnetoresistive sensing value, generate a first arithmetic value based on the weight value and the Hall sensing value, generate a second arithmetic value based on the weight value and the magnetoresistive sensing value, and perform an addition operation on the first arithmetic value, the second arithmetic value, and the magnetoresistive sensing value to generate an output signal with an output value. The output value is related to the strength of the magnetic field. The Hall sensor provides a first sensed value and a first reference value. The magnetoresistive sensor provides a second sensed value and a second reference value. Wherein the higher the second sensed value, the higher the weight value, and The lower the second sensed value, the lower the weight value.

2. The magnetic field sensing device according to claim 1, characterized in that, The magnetoresistive sensor is one of anisotropic magnetoresistive sensors, giant magnetoresistive sensors, and tunnel magnetoresistive sensors.

3. The magnetic field sensing device according to claim 1, characterized in that, The magnetoresistive sensing value is proportional to the weight value.

4. The magnetic field sensing device according to claim 1, characterized in that: The difference between the first sensed value and the first reference value is equal to the Hall sensed value, and The difference between the second sensed value and the second reference value is equal to the magnetoresistive sensed value.

5. The magnetic field sensing device according to claim 4, characterized in that, The arithmetic circuit includes: A weighted signal generator, coupled to the magnetoresistive sensor, is configured to respond to the second sensed value to generate a weighted signal having the weighted value; A first multiplication circuit, coupled to the Hall sensor and the weight signal generator, is configured to perform a first multiplication operation based on the first sensed value, the first reference value, and the weight value to generate the first calculated value. A second multiplication circuit, coupled to the magnetoresistive sensor and the weight signal generator, is configured to perform a second multiplication operation based on the second sensed value, the second reference value, and the weight value to generate the second calculated value; and An adder, coupled to the magnetoresistive sensor, the first multiplication circuit, and the second multiplication circuit, is configured to perform operations on the first calculated value, the second calculated value, and the magnetoresistive sensing value to generate an output signal having the output value.

6. The magnetic field sensing device according to claim 5, characterized in that: The weighting signal is a pulse width modulation signal, and The weight value is positively correlated with the working period of the weight signal.

7. The magnetic field sensing device according to claim 6, characterized in that, The higher the second sensed value, the longer the working cycle of the weighted signal.

8. The magnetic field sensing device according to claim 5, characterized in that, The weight signal generator includes: A comparator, wherein the non-inverting input of the comparator receives the second sensed value, and the inverting input of the comparator receives a reference triangular wave signal. The comparator compares the second sensed value with the voltage value of the reference triangular wave signal to generate the weighted signal.

9. The magnetic field sensing device according to claim 5, characterized in that, The first multiplication circuit includes: A first multiplier has a positive input terminal that receives the first sensed value, a negative input terminal that receives the first reference value, a control terminal that receives the weighting signal, and an output terminal that outputs the first calculated value.

10. The magnetic field sensing device according to claim 9, characterized in that, The second multiplication circuit includes: The second multiplier has a positive input terminal that receives the second reference value, a negative input terminal that receives the second sensed value, a control terminal that receives the weight signal, and an output terminal that outputs the second calculated value.

11. The magnetic field sensing device according to claim 10, characterized in that: The first multiplication circuit includes: A first switch, wherein a first terminal of the first switch is coupled to the positive input terminal of the first multiplier, a second terminal of the first switch is coupled to the output terminal of the first multiplier, and a control terminal of the first switch receives the weighting signal; and A second switch has its first terminal coupled to the negative input terminal of the first multiplier, and its second terminal coupled to the output terminal of the first multiplier. The control terminal of the second switch receives the weighting signal. The second multiplication circuit includes: A third switch, wherein a first terminal of the third switch is coupled to the positive input terminal of the second multiplier, a second terminal of the third switch is coupled to the output terminal of the second multiplier, and a control terminal of the third switch receives the weighting signal; and A fourth switch, the first end of which is coupled to the negative input terminal of the second multiplier, the second end of which is coupled to the output terminal of the second multiplier, and the control terminal of the fourth switch receiving the weight signal.

12. The magnetic field sensing device according to claim 11, characterized in that: The first switch and the third switch are turned on in response to a positive pulse of the weighting signal and turned off in response to a low voltage level of the weighting signal. The second switch and the fourth switch are turned off in response to a positive pulse of the weighting signal and turned on in response to a low voltage level of the weighting signal.

13. The magnetic field sensing device according to claim 10, characterized in that: The first calculated value is equal to the product of the weight value and the first sensed value. The second calculated value is equal to the product of the weight value and the negative of the second sensed value, and The output value is equal to the result of the inverse addition of the first calculated value, the second calculated value, and the magnetoresistive sensing value.

14. The magnetic field sensing device according to claim 5, characterized in that, The adder includes: An operational amplifier, wherein the non-inverting input terminal of the operational amplifier receives a reference voltage, and the output terminal of the operational amplifier is used to output the output signal; A first resistor is coupled between the first multiplication circuit and the inverting input of the operational amplifier; The second resistor is coupled between the second multiplication circuit and the inverting input of the operational amplifier; A third resistor, the first end of which receives the second sensed value, and the first end of which is coupled to the inverting input of the operational amplifier; and The fourth resistor is coupled between the inverting input terminal and the output terminal of the operational amplifier.

15. The magnetic field sensing device according to claim 14, characterized in that, The resistance values ​​of the first resistor, the second resistor, the third resistor, and the fourth resistor are all the same.

16. The magnetic field sensing device according to claim 14, characterized in that, The adder also includes: A capacitor is coupled between the inverting input terminal and the output terminal of the operational amplifier.

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