JP2020187014A - Sensor device - Google Patents

Abstract

To provide a sensor device with which it is possible to reduce the influence of a disturbance magnetic field, the influence of stresses exerted on each bridge circuit and an error due to in-circuit noise.SOLUTION: A first connecting part 305 shorts the other end side of a first wiring path 301 and the other end side of a fourth wiring path 304 together. The disturbance magnetic field component included in a first voltage signal and the disturbance magnetic field component included in a fourth voltage signal are thereby canceled out. A second connecting part 306 shorts the other end side of a second wiring path 302 and the other end side of a third wiring path 303 together. The disturbance magnetic field component included in a second voltage signal and the disturbance magnetic field component included in a third voltage signal are thereby canceled out. An electronic circuit part 350 acquires a difference voltage between the voltage of the first connecting part 305 and the voltage of the second connecting part 306, so that the stress components occurring in bridge circuits 130, 230 are canceled out, and further acquires a sensor signal with which in-circuit noise components are canceled out.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sensor device.

Conventionally, for example, Patent Document 1 has proposed a magnetic isolator configured to reduce the influence of a uniform disturbance magnetic field. The magnetic isolator includes a first insulating layer and a second insulating layer provided on the installation substrate.

On the first insulating layer, four magnetoresistive elements constituting the bridge circuit are arranged. On the second insulating layer, a signal input conductor provided facing each magnetoresistive sensor and a signal input folded conductor are connected via a signal input connecting wire. The signal input line is arranged.

Then, when the signal current is applied to the signal input line, the direction of the magnetic field applied to the two elements constituting the first half-bridge circuit and the direction of the magnetic field applied to the two elements constituting the second half-bridge circuit are applied. The signal input line is configured so that the direction of the magnetic field to be generated is opposite to that of the magnetic field.

As a result, the equilibrium of the bridge circuit is not disturbed with respect to a uniform disturbance magnetic field, and the influence of the application of the uniform disturbance magnetic field on the output signal is reduced.

Japanese Unexamined Patent Publication No. 2012-105060

Here, as a configuration different from the above-mentioned conventional technique, the two bridge circuits are physically separated from each other so that the disturbance magnetic field has the opposite phase of the signal component, and each output signal of each bridge circuit is arranged by the arithmetic circuit. It is conceivable to reduce the influence of the disturbance magnetic field by calculating the differential of. In this configuration, it is necessary to physically separate the two bridge circuits, and it is conceivable that the two bridge circuits are formed on separate sensor chips or formed at a distance within the same sensor chip.

However, in any case, since the bridge circuits are physically separated, the stress applied to each magnetoresistive element constituting the bridge circuit is different for each element. Therefore, the influence of the stress included in each output signal is also different. Therefore, the influence of the stress applied to each magnetoresistive element cannot be canceled by the differential of each output signal.

Moreover, since each bridge circuit is physically separated, the wiring from each bridge circuit to the arithmetic circuit is independent. Therefore, the noise in the circuit cannot be made common until each wiring runs in parallel in the circuit. Therefore, the error due to the noise in the circuit cannot be canceled by the differential of each output signal.

In view of the above points, it is an object of the present invention to provide a sensor device capable of reducing the influence of a disturbance magnetic field, the influence of stress applied to each bridge circuit, and an error due to noise in the circuit.

In order to achieve the above object, in the invention according to claim 1, the sensor device includes a first sensor unit (100, 500), a second sensor unit (200, 500), and a signal processing unit (300).

The first sensor unit has a first magnetoresistive element pair (110) and a second magnetoresistive element pair (120) constituting the first bridge circuit (130). The first sensor unit changes the resistance values of the first magnetoresistive element pair and the second magnetoresistive element pair when the detection target is affected by the magnetic field, the first stress applied to the first bridge circuit, and the input from the outside. The first voltage signal at the first midpoint (113) of the first magnetoresistive sensor pair and the second voltage at the second midpoint (123) of the second magnetoresistive sensor pair based on the disturbance magnetic field that will be generated. Outputs a signal.

The second sensor unit is arranged away from the first sensor unit so that the phase of the magnetic field received from the detection target is out of phase. The second sensor unit has a third magnetoresistive element pair (210) and a fourth magnetoresistive element pair (220) constituting the second bridge circuit (230). The second sensor unit responds to changes in the resistance values of the third magnetoresistive element pair and the fourth magnetoresistive element pair when affected by a magnetic field from the detection target, the second stress applied to the second bridge circuit, and the disturbance magnetic field. Based on this, the third voltage signal at the third midpoint (213) of the third magnetoresistive sensor pair whose polarity is inverted with respect to the first midpoint and the polarity are inverted with respect to the second midpoint. The fourth voltage signal at the fourth midpoint (223) of the fourth magnetoresistive sensor pair is output.

The signal processing unit includes a first wiring path (301), a first filter (310), a second wiring path (302), a second filter (320), a third wiring path (303), and a third filter (330). It has a fourth wiring path (304) and a fourth filter (340).

A first voltage signal at the first midpoint is applied to one end of the first wiring path. The first filter is provided in the middle of the first wiring path and reduces the noise in the circuit input to the first wiring path. A second voltage signal at the second midpoint is applied to one end of the second wiring path. The second filter is provided in the middle of the second wiring path and reduces the noise in the circuit input to the second wiring path.

A third voltage signal at the third midpoint is applied to one end of the third wiring path. The third filter is provided in the middle of the third wiring path and reduces the noise in the circuit input to the third wiring path. A fourth voltage signal at the fourth midpoint is applied to one end of the fourth wiring path. The fourth filter is provided in the middle of the fourth wiring path and reduces the noise in the circuit input to the fourth wiring path.

Further, the signal processing unit has a first connection unit (305), a second connection unit (306), and an electronic circuit unit (350).

The first connection portion is a connection portion in which the other end side of the first wiring path and the other end side of the fourth wiring path are short-circuited, and the first voltage signal and the fourth after passing through the first filter. The fourth voltage signal after passing through the filter is averaged. As a result, the first connection portion cancels out the component of the disturbance magnetic field included in the first voltage signal and the component of the disturbance magnetic field included in the fourth voltage signal. The first connection portion averages the first stress component included in the first voltage signal and the second stress component included in the fourth voltage signal. The first connection portion is input to the first wiring path and contains a component of in-circuit noise contained in the first voltage signal, and is input to the fourth wiring path and contains a component of in-circuit noise contained in the fourth voltage signal. To average.

The second connection portion is a connection portion in which the other end side of the second wiring path and the other end side of the third wiring path are short-circuited, and the second voltage signal and the third after passing through the second filter. The third voltage signal after passing through the filter is averaged. As a result, the second connection portion cancels out the component of the disturbance magnetic field included in the second voltage signal and the component of the disturbance magnetic field included in the third voltage signal. The second connection portion averages the first stress component included in the second voltage signal and the second stress component included in the third voltage signal. The second connection portion is input to the second wiring path and contains a component of in-circuit noise contained in the second voltage signal, and is input to the third wiring path and contains a component of in-circuit noise contained in the third voltage signal. To average.

By acquiring the difference voltage between the voltage of the first connection part and the voltage of the second connection part, the electronic circuit unit cancels out the first stress component and the second stress component, and further, the noise component in the circuit. Gets the sensor signal that is canceled.

As described above, the sensor device has a configuration in which voltage signals whose polarities are electrically inverted and whose phases are magnetically inverted are averaged by the first connection portion and the second connection portion. As a result, the components of the disturbance magnetic fields having opposite phases can be canceled at each connection portion. Further, since the difference voltage between the averaged positive electrode side voltage and the negative electrode side voltage is acquired, the averaged stress component included in the positive electrode side voltage, the circuit noise component, and the negative electrode side It is possible to cancel each averaged stress component and the circuit noise component contained in the voltage. Therefore, with respect to the sensor signal acquired by the signal processing unit, it is possible to reduce the influence of the disturbance magnetic field, the influence of the stress applied to each bridge circuit, and the error due to the noise in the circuit.

The reference numerals in parentheses of each means described in this column and the scope of claims indicate the correspondence with the specific means described in the embodiments described later.

It is a figure which showed the whole structure of the sensor device which concerns on 1st Embodiment. It is a figure which showed the differential voltage obtained when the influence of a disturbance magnetic field, stress, and noise in a circuit occurs. It is a figure which showed the whole structure of the sensor device which concerns on 2nd Embodiment. It is a figure which showed the whole structure of the sensor device which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the same or equal parts are designated by the same reference numerals in the drawings.

(First Embodiment)
Hereinafter, the first embodiment will be described with reference to the drawings. The sensor device according to the present embodiment functions as, for example, a magnetic sensor that detects the position of a detection target that moves in one direction, or a current sensor that detects a current flowing through wiring as a detection target.

As shown in FIG. 1, the sensor device 1 includes a first sensor chip 100, a second sensor chip 200, and a signal processing unit 300.

The first sensor chip 100 and the second sensor chip 200 are circuit units configured to output a voltage signal which is an analog signal corresponding to the influence of a magnetic field received from a detection target. Each sensor chip 100, 200 is configured as, for example, a chip component.

The first sensor chip 100 has a first magnetoresistive element pair 110 and a second magnetoresistive element pair 120. The first magnetoresistive element pair 110 constitutes a half-bridge circuit by two magnetoresistive elements 111 and 112 connected in series between the power supply (VDD1) and the ground (GND1) supplied from the signal processing unit 300. There is. Similarly, the second magnetoresistive element pair 120 constitutes a half-bridge circuit by two magnetoresistive elements 121 and 122 connected in series between the power supply and the ground. The first magnetoresistive element pair 110 and the second magnetoresistive element pair 120 constitute the first bridge circuit 130.

The first sensor chip 100 outputs a first voltage signal at the first midpoint 113 of the first magnetoresistive element pair 110 and a second voltage signal at the second midpoint 123 of the second magnetoresistive element pair 120, respectively. To do.

The second sensor chip 200 has a third magnetoresistive element pair 210 and a fourth magnetoresistive element pair 220. The third magnetoresistive element pair 210 constitutes a half-bridge circuit by two magnetoresistive elements 211 and 212 connected in series between the power supply (VDD2) and the ground (GND2) supplied from the signal processing unit 300. There is. Similarly, the fourth magnetoresistive element pair 220 constitutes a half-bridge circuit by two magnetoresistive elements 221 and 222 connected in series between the power supply and the ground. The third magnetoresistive element pair 210 and the third magnetoresistive element pair 210 constitute the second bridge circuit 230.

The second sensor chip 200 outputs a third voltage signal at the third midpoint 213 of the third magnetoresistive element pair 210 and a fourth voltage signal at the fourth midpoint 223 of the fourth magnetoresistive element pair 220. ..

Here, the output of the second sensor chip 200 electrically reverses the polarity with respect to the first sensor chip 100, and magnetically reverses the phase. Therefore, the second sensor chip 200 is arranged at a certain distance from the first sensor chip 100 so that the phase of the magnetic field received from the detection target is out of phase. Further, the third voltage signal at the third midpoint 213 of the third magnetoresistive element pair 210 has an electrical polarity reversed with respect to the first midpoint 113. The fourth voltage signal at the fourth midpoint 223 of the fourth magnetoresistive sensor pair 220 has an electrical polarity reversed with respect to the second midpoint 123.

The signal processing unit 300 is a circuit component that processes each voltage signal output from each of the sensor chips 100 and 200. The signal processing unit 300 is configured as, for example, an ASIC. The signal processing unit 300 and the sensor chips 100 and 200 are electrically connected by a wire 400.

The signal processing unit 300 includes a first wiring path 301, a second wiring path 302, a third wiring path 303, a fourth wiring path 304, a first filter 310, a second filter 320, a third filter 330, and a fourth filter 340. Has.

A first voltage signal at the first midpoint of the first magnetoresistive element pair 110 is applied to one end of the first wiring path 301. A second voltage signal at the second midpoint of the second magnetoresistive sensor pair 120 is applied to one end of the second wiring path 302. A third voltage signal at the third midpoint of the third magnetoresistive element pair 210 is applied to one end of the third wiring path 303. A fourth voltage signal at the fourth midpoint of the fourth magnetoresistive element pair 220 is applied to one end of the fourth wiring path 304.

Most of the wiring paths 301 to 304 are formed in the signal processing unit 300 so as to run parallel to each other in the signal processing unit 300, that is, to be parallel to each other.

The first filter 310 is provided in the middle of the first wiring path 301 and reduces the noise in the circuit input to the first wiring path 301. The noise in the circuit is, for example, noise caused by a circuit such as noise generated in each of the sensor chips 100 and 200, noise generated in the electronic circuit unit 350, and noise from the outside of the sensor device 1.

The first filter 310 is composed of a resistance element 311 provided in the first wiring path 301, and a capacitor 312 connected between the other end side of the first wiring path 301 and the ground in the resistance element 311. It is an RC filter.

The second filter 320 is provided in the middle of the second wiring path 302, and reduces the noise in the circuit input to the second wiring path 302. The second filter 320 is composed of a resistance element 321 provided in the second wiring path 302, and a capacitor 322 connected between the other end side of the second wiring path 302 and the ground in the resistance element 321. It is an RC filter.

The third filter 330 is provided in the middle of the third wiring path 303, and reduces the noise in the circuit input to the third wiring path 303. The third filter 330 is composed of a resistance element 331 provided in the third wiring path 303, and a capacitor 332 connected between the other end side of the third wiring path 303 and the ground in the resistance element 331. It is an RC filter.

The fourth filter 340 is provided in the middle of the fourth wiring path 304, and reduces the noise in the circuit input to the fourth wiring path 304. The fourth filter 340 is composed of a resistance element 341 provided in the fourth wiring path 304 and a capacitor 342 connected between the other end side of the fourth wiring path 304 and the ground in the resistance element 341. It is an RC filter.

The resistance elements 311, 321, 331, and 341 all have the same resistance value. The capacitors 312, 322, 332, and 342 all have the same capacitance value.

Further, the signal processing unit 300 includes a first connection unit 305, a second connection unit 306, and an electronic circuit unit 350.

The first connection portion 305 is a connection portion in which the other end side of the first wiring path 301 and the other end side of the fourth wiring path 304 are short-circuited. It can be said that the first connection portion 305 is the midpoint between the resistance element 311 and the resistance element 341. The first connection unit 305 is connected to the electronic circuit unit 350.

The second connection portion 306 is a connection portion in which the other end side of the second wiring path 302 and the other end side of the third wiring path 303 are short-circuited. It can be said that the second connection portion 306 is the midpoint between the resistance element 321 and the resistance element 331. The second connection unit 306 is connected to the electronic circuit unit 350.

The electronic circuit unit 350 is a circuit component for acquiring the difference voltage between the voltage of the first connection unit 305 and the voltage of the second connection unit 306 as a sensor signal and outputting the sensor signal to the outside. The electronic circuit unit 350 includes an AFE351, a DSP352, and an output unit 353.

The AFE351 is an analog circuit unit (Analog Front End) that acquires a sensor signal, which is the difference voltage between the voltage of the first connection unit 305 and the voltage of the second connection unit 306, and performs processing such as amplification and offset of the sensor signal. is there. An analog circuit is formed from one end side of each wiring path 301 to 304 to AFE351.

The DSP352 is a digital circuit unit (Digital Signal Processor) that A / D-converts and digitizes the sensor signal input from the AFE351. The clock handled by the DSP352 may become noise in the circuit.

The output unit 353 converts the sensor signal into a predetermined output format and outputs the sensor signal to an external device (not shown) via the output terminal 307. The predetermined output format is an analog signal after D / A conversion, PWM (Pulse Width Modulation) communication, SENT (Single Edge Nibble Transmission) communication which is a kind of digital communication, and the like.

The above is the overall configuration of the sensor device 1. The sensor device 1 includes a power supply terminal 308 and a ground terminal 309 connected to an external device. The sensor device 1 operates by supplying power from an external device via the power supply terminal 308 and the ground terminal 309.

Next, the operation of the sensor device 1 will be described. First, the first sensor chip 100 is based on the changes in the resistance values of the magnetoresistive sensor pairs 110 and 120 when the detection target is affected by the magnetic field, the first stress applied to the first bridge circuit 130, and the disturbance magnetic field. A first voltage signal and a second voltage signal are output from. The disturbing magnetic field is magnetic noise that will be input from the outside. The disturbance magnetic field may or may not be input.

The first voltage signal and the second voltage signal include a component of the disturbance magnetic field and a component of the first stress applied to the first bridge circuit 130. The first stress is generated in each magnetoresistive element 111, 112, 121, 122 due to the difference in the position where each magnetoresistive element 111, 112, 121, 122 is formed on a substrate (not shown) constituting the first sensor chip 100. It is stress. The first stress also includes the stress generated when the first sensor chip 100 is assembled at a predetermined position.

The first voltage signal is input to the first wiring path 301. When in-circuit noise is input to the first wiring path 301, the first voltage signal includes a component of in-circuit noise. The second voltage signal is input to the second wiring path 302. When in-circuit noise is input to the second wiring path 302, the second voltage signal includes a component of in-circuit noise.

Similarly, the second sensor chip is based on the change in the resistance value of each magnetoresistive element pair 210 and 220 when affected by the magnetic field from the detection target, the second stress applied to the second bridge circuit 230, and the disturbance magnetic field. A third voltage signal and a fourth voltage signal are output from 200.

The third voltage signal and the fourth voltage signal include a component of the disturbance magnetic field and a component of the second stress applied to the second bridge circuit 230. The second stress is generated in each magnetoresistive element 211, 212, 2222, 222 due to the difference in the position where each magnetoresistive element 211, 212, 211, 222 is formed on a substrate (not shown) constituting the second sensor chip 200. It is stress. The second stress also includes the stress generated when the second sensor chip 200 is separated from the first sensor chip 100 and assembled at a predetermined position.

The third voltage signal is input to the third wiring path 303. When in-circuit noise is input to the third wiring path 303, the third voltage signal includes a component of in-circuit noise. The fourth voltage signal is input to the fourth wiring path 304. When in-circuit noise is input to the fourth wiring path 304, the fourth voltage signal includes a component of in-circuit noise.

Since the first wiring path 301 and the fourth wiring path 304 are short-circuited by the first connection portion 305, the first voltage signal after passing through the first filter 310 and the fourth after passing through the fourth filter 340 are used. The voltage signal is averaged. As a result, the component of the disturbance magnetic field contained in the first voltage signal and the component of the magnetically opposite phase disturbance magnetic field contained in the fourth voltage signal are canceled out.

Further, the component of the first stress included in the first voltage signal and the component of the second stress contained in the fourth voltage signal are averaged. Further, the component of the noise in the circuit included in the first voltage signal and the component of the noise in the circuit contained in the fourth voltage signal are averaged. That is, the noise in the circuit of the first wiring path 301 and the noise in the circuit of the fourth wiring path 304 are shared.

Similarly, since the second wiring path 302 and the third wiring path 303 are short-circuited by the second connection portion 306, the second voltage signal after passing through the second filter 320 and the second after passing through the third filter 330 are used. The three voltage signals are averaged. As a result, the component of the disturbance magnetic field contained in the second voltage signal and the component of the magnetically opposite phase disturbance magnetic field contained in the third voltage signal are canceled out.

Further, the component of the first stress included in the second voltage signal and the component of the second stress contained in the third voltage signal are averaged. Further, the component of the noise in the circuit included in the second voltage signal and the component of the noise in the circuit included in the third voltage signal are averaged. That is, the noise in the circuit of the second wiring path 302 and the noise in the circuit of the third wiring path 303 are shared.

The voltage of the first connection portion 305 includes a component obtained by averaging the first stress component and the second stress component, a noise component in the circuit of the first wiring path 301, and a circuit of the fourth wiring path 304. A component obtained by averaging the noise component and a component are included. Further, the voltage of the second connection portion 306 includes a component obtained by averaging the first stress component and the second stress component, a noise component in the circuit of the second wiring path 302, and a third wiring path 303. A component obtained by averaging the component of noise in the circuit and a component are included.

In the AFE351, the difference voltage between the voltage of the first connection portion 305 and the voltage of the second connection portion 306 is acquired, so that the first stress component and the second stress component are canceled, and further, noise in the circuit is generated. The ingredients are counteracted. Therefore, the DSP352 acquires a sensor signal from which the components of the disturbance magnetic field, the components of the first stress and the second stress, and the components of the noise in the circuit are removed.

A specific example of the above signal processing will be described. Specifically, point A of the first wiring path 301, point B of the second wiring path 302, point C of the third wiring path 303, point D of the fourth wiring path 304, point E of the first connection portion 305, Refer to each signal at point F of the second connection portion 306.

Then, the center voltage of each of the bridge circuits 130 and 230 is set to Vref. Let the signal component from the detection target be ΔVs, the disturbance magnetic field be ΔVn, the second stress component be ΔVf, and the noise component in the circuit be ΔVc.

As shown in FIG. 2, for example, when there is no signal from the detection target and there is no noise component, all points A to D are Vref. Since point E is the average value of points A and D, it is Vref, and point F is the average value of points B and C, so it is Vref. Therefore, the difference voltage (point E-point F) becomes 0.

If there is a signal from the detection target and there is no noise component, point A is Vref + ΔVs, point B is Vref-ΔVs, and point C is electrically reversed in polarity, so Vref-ΔVs and point D are electrical. Since the polarity is reversed, Vref + ΔVs. Since point E is the average value of points A and D, it is Vref + ΔVs. Since point F is the average value of points B and C, it becomes Vref−ΔVs. Therefore, the difference voltage (point E-point F) is 2ΔVs.

When there is a disturbance magnetic field, point A is Vref + ΔVn, point B is Vref-ΔVn, point C is magnetically inverted, so Vref + ΔVn, and point D is magnetically inverted, so Vref-ΔVn. Become. Since the point E is the average value of the points A and D, ΔVn is canceled and becomes Vref. Since the F point is the average value of the B point and the C point, ΔVn is canceled and becomes Vref. Therefore, the difference voltage (point E-F) becomes 0, and the difference voltage does not include the component of the disturbance magnetic field.

For example, when a second stress is generated in the second bridge circuit 230, the point A becomes Vref because the first stress is not generated, and the point B also becomes Vref because the first stress is not generated. Point C is Vref + ΔVf because it contains a component caused by the second stress, and point D is also Vref + ΔVf because it contains a component caused by the second stress. Since point E is the average value of points A and D, it is (2Vref + ΔVf) / 2. Since point F is the average value of points B and C, it is (2Vref + ΔVf) / 2. Therefore, the difference voltage (point E-F) becomes 0, and the component of the second stress is removed.

When in-circuit noise is generated in the first bridge circuit 130, point A becomes Vref-ΔVc due to the influence of the in-circuit noise, and point B also becomes Vref-ΔVc due to the influence of the in-circuit noise. Points C and D are Vrefs because they are not affected by noise in the circuit. Since point E is the average value of points A and D, it is (2Vref−ΔVc) / 2. Since point F is the average value of points B and C, it is (2Vref−ΔVc) / 2. Therefore, the difference voltage (point E-F) becomes 0, and the noise component in the circuit is removed.

Each noise shown in FIG. 2 is an example, and each electric signal includes the influence of a plurality of noises. However, if it is a disturbance magnetic field as described above, it is canceled by averaging at points E and F, and stress is applied. And noise in the circuit is removed by taking the difference voltage. Therefore, with respect to the sensor signal acquired by the signal processing unit 300, it is possible to reduce all of the influence of the disturbance magnetic field, the influence of the stress applied to each of the bridge circuits 130 and 230, and the error due to the noise in the circuit.

In particular, the first connection unit 305 and the second connection unit 306 add each electric signal in an analog manner. Therefore, it is possible to reduce the error component without causing a time lag as compared with the case of signal processing by time division.

Regarding the correspondence between the description of the present embodiment and the description of the claims, the first sensor chip 100 corresponds to the "first sensor unit" of the claims, and the second sensor chip 200 claims the patent. Corresponds to the "second sensor unit" in the range of.

(Second Embodiment)
In this embodiment, a part different from the first embodiment will be mainly described. As shown in FIG. 3, the first filter 310 is composed of the resistance element 311. As described above, the first filter 310 does not have to have the capacitor 312. The same applies to the second filter 320, the third filter 330, and the fourth filter 340. The resistance elements 311, 321, 331, and 341 all have the same resistance value.

(Third Embodiment)
In this embodiment, the parts different from the first and second embodiments will be mainly described. As shown in FIG. 4, each of the bridge circuits 130 and 230 is formed on one third sensor chip 500.

In this configuration, the two bridge circuits 130 and 230 are physically separated from each other in the third sensor chip 500. As described above, the sensor device 1 may be configured to include one third sensor chip 500.

Regarding the correspondence between the description of the present embodiment and the description of the claims, the portion of the third sensor chip 500 corresponding to the first bridge circuit 130 is the "first sensor unit" of the claims. Correspond. Further, the portion of the third sensor chip 500 corresponding to the second bridge circuit 230 corresponds to the "second sensor portion" in the claims.

(Other embodiments)
The configuration of the sensor device 1 shown in each of the above embodiments is an example, and the configuration is not limited to the configuration shown above, and other configurations capable of realizing the present invention may be used. For example, a semiconductor switch can be provided in each wiring path 301 to 304. In addition, DSP352 controls each switch. As a result, the signal of either one of the sensor chips 100 and 200 can be taken out. When the bridge circuits 130 and 230 are formed on one third sensor chip 500, the signal of any one of the bridge circuits 130 and 230 can be taken out.

The electronic circuit unit 350 may be configured as an analog circuit such as a circuit that does not include a digital circuit, for example, a differential amplifier circuit. In this case, the acquired sensor signal is output to the outside as an analog signal as it is.

100, 200, 500 Sensor chip 110, 120, 210, 220 Magneto resistive sensor pair 113, 123, 213, 223 Midpoint 130, 230 Bridge circuit 300 Signal processing unit 301, 302, 303, 304 Wiring path 305, 306 Connection unit 310, 320, 330, 340 Filter 350 Electronic circuit section

Claims (3)

The first magnetoresistive element having a first magnetoresistive element pair (110) and a second magnetoresistive element pair (120) constituting the first bridge circuit (130) and being affected by a magnetic field from a detection target. The first of the first magnetoresistive sensor pair is based on the change in the resistance value of the pair and the second magnetoresistive element pair, the first stress applied to the first bridge circuit, and the disturbance magnetic field that will be input from the outside. A first sensor unit (100, 500) that outputs a first voltage signal at the midpoint (113) and a second voltage signal at the second midpoint (123) of the second magnetoresistive sensor pair.
The third magnetoresistive element pair (210) and the fourth magnetoresistive sensor, which are arranged apart from the first sensor unit so that the phases of the magnetic fields received from the detection target are opposite to each other and constitute the second bridge circuit (230). It has an element pair (220), and changes in the resistance values of the third magnetoresistive element pair and the fourth magnetoresistive element pair when affected by a magnetic field from the detection target, and the second bridge circuit. The third voltage signal at the third midpoint (213) of the third magnetoresistive sensor pair whose polarity is reversed with respect to the first midpoint based on the two stresses and the disturbance magnetic field, and the second midpoint. A second sensor unit (200, 500) that outputs a fourth voltage signal at the fourth midpoint (223) of the fourth magnetoresistive sensor pair whose polarity is reversed with respect to the midpoint.
The first wiring path (301) to which the first voltage signal of the first middle point (113) is applied to one end side, and the first wiring path provided in the middle of the first wiring path and input to the first wiring path. A first filter (310) that reduces noise in the circuit, a second wiring path (302) to which the second voltage signal of the second middle point is applied to one end side, and an intermediate of the second wiring path. A second filter (320) for reducing in-circuit noise input to the second wiring path and a third wiring to which the third voltage signal at the third middle point is applied to one end side. A path (303), a third filter (330) provided in the middle of the third wiring path and reducing in-circuit noise input to the third wiring path, and the fourth midpoint on one end side. A fourth wiring path (304) to which the fourth voltage signal is applied, and a fourth filter provided in the middle of the fourth wiring path and reducing in-circuit noise input to the fourth wiring path. (340), and a signal processing unit (300) having
Including
The signal processing unit
It is a connection point where the other end side of the first wiring path and the other end side of the fourth wiring path are short-circuited, and the first voltage signal and the fourth filter after passing through the first filter. By averaging the fourth voltage signal after passing through the above, the component of the disturbance magnetic field contained in the first voltage signal and the component of the disturbance magnetic field contained in the fourth voltage signal are canceled out, and the component of the disturbance magnetic field is canceled. The component of the first stress contained in the first voltage signal and the component of the second stress contained in the fourth voltage signal are averaged and input to the first wiring path and included in the first voltage signal. A first connection unit (305) that averages the components of noise in the circuit and the components of noise in the circuit that are input to the fourth wiring path and included in the fourth voltage signal.
It is a connection point where the other end side of the second wiring path and the other end side of the third wiring path are short-circuited, and the second voltage signal and the third filter after passing through the second filter. By averaging the third voltage signal after passing through the above, the component of the disturbance magnetic field contained in the second voltage signal and the component of the disturbance magnetic field contained in the third voltage signal are canceled out, and the component of the disturbance magnetic field is canceled. The component of the first stress contained in the two voltage signals and the component of the second stress contained in the third voltage signal are averaged and input to the second wiring path and included in the second voltage signal. A second connection portion (306) that averages the components of the noise in the circuit and the components of the noise in the circuit that are input to the third wiring path and included in the third voltage signal.
By acquiring the difference voltage between the voltage of the first connection portion and the voltage of the second connection portion, the component of the first stress and the component of the second stress are canceled, and further, the component of the noise in the circuit is canceled. The electronic circuit unit (350) that acquires the sensor signal that cancels out
Sensor device with. The first filter, the second filter, the third filter, and the fourth filter each have a resistance element (311 and 321, 331, 341) having the same resistance value and a capacitor (312, 322,) having the same capacitance value. The sensor device according to claim 1, which is an RC filter composed of 332, 342). The sensor according to claim 1, wherein each of the first filter, the second filter, the third filter, and the fourth filter is composed of resistance elements (311, 321, 331, 341) having the same resistance value. apparatus.

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