JP2012215498A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor having a hall element, capable of removing an offset voltage and flicker noise contained in output voltage of the hall element in a signal processing circuit having a simple circuit configuration.SOLUTION: A hall plate H is formed by a bipolar material capable of making the kind of the carrier of a current flowing through the hole plate H either an electron or a hole according to the potential Vg of a gate electrode G. Further, input/output terminals TA, TA', TB, TB' become a current input terminal pair and a voltage output terminal pair opposing in the face of the hole plate H. At that time, the current input terminal pair and voltage output terminal pair are formed at a position where they orthogonally intersect with each other.

Description

  The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor having a Hall element that detects the strength of a magnetic field using the Hall effect.

As one of magnetic sensors for detecting the strength of a magnetic field, a magnetic sensor having a Hall element that detects the strength of a magnetic field using the Hall effect is generally known. The Hall effect is a phenomenon in which a voltage is generated when electrons or holes moving in a magnetic field receive a force acting in a direction perpendicular to the direction of the magnetic field and the direction of movement of the electrons or holes. .
Here, with reference to FIG. 5, the general configuration and operation of a general Hall element 100 in the prior art will be described. The Hall element 100 shown in FIG. 5 generally has a Hall plate H having a Hall effect and four input / output terminals TA, TA ′, TB, TB ′ at positions that are four-fold symmetric about the center thereof. It is prepared for. The direction of the applied magnetic field will be described as a direction perpendicular to the paper surface.

  The hall plate H is formed using a material having a hall effect. The input / output terminals TA, TA ′, TB, TB ′ are a set of the input / output terminal TA and the input / output terminal TA ′, and the input / output terminal TB and the input / output terminal TB ′. ing. The Hall element 100 is between two input / output terminals (hereinafter referred to as “current input terminal pair”) corresponding to the moving direction of electrons or holes among the input / output terminals TA, TA ′, TB, TB ′. By supplying a current, a potential difference corresponding to the magnetic field applied between the other two input / output terminals (hereinafter referred to as “voltage output terminal pair”) in the direction orthogonal to the moving direction of electrons or holes is output. . For example, the Hall element 100 outputs a potential difference according to the applied magnetic field between the voltage output terminal pair TB-TB 'by causing a current to flow between the current input terminal pair TA-TA'.

The potential difference output between the voltage output terminal pair is proportional to the magnetic flux density of the applied magnetic field, and is ideally zero when the magnetic flux density is zero. However, even if the magnetic flux density is zero due to variations in the manufacturing process of the Hall element 100, the potential difference output between the pair of voltage output terminals does not become zero, and a so-called offset voltage often occurs in the potential difference.
As a method for removing the offset voltage, a spinning current method is generally used (see Patent Document 1). In this method, the current input terminal pair and the voltage output terminal pair of the Hall element 100 are alternately switched. As a result, the offset voltage is removed by making the offset voltage before and after switching the current input terminal pair and the voltage output terminal pair alternately in a reverse phase relationship. This is similar to making the Wheatstone bridge non-equilibrium.

Here, the Hall coefficient of the Hall element 100 is Rh, the thickness of the Hall plate H is d, the current value of the current flowing between the current input terminal pair is I, and the magnetic flux of the magnetic field applied between the voltage output terminal pair. The density is B and the offset voltage is Voff. Then, the potential difference V1 output between the voltage output terminal pair TB-TB ′ when the current of the current value I is passed between the current input terminal pair TA-TA ′ is expressed by the following equation (1). Can be expressed as Further, when the current input terminal pair TA-TA ′ and the voltage output terminal pair TB-TB ′ are switched and a current having a current value I flows between the current input terminal pair TB-TB ′, the voltage output terminal pair TA− The potential difference V2 output between TA ′ can be expressed as the following equation (2).
V1 = Rh / d × I × B + Voff (1)
V2 = Rh / d × I × B−Voff (2)

  Therefore, the offset voltage Voff can be removed by adding the potential difference V1 output between the voltage output terminal pair TB-TB ′ and the potential difference V2 output between the voltage output terminal pair TA-TA ′. . At this time, flicker noise that is a noise component whose intensity is inversely proportional to the frequency of the output voltage (signal) output from the Hall element 100 can also be removed. Thus, by removing the offset voltage Voff and flicker noise, a potential difference corresponding to the magnetic field proportional to the magnetic flux density B can be obtained.

JP 2001-337147 A

However, in the Hall element 100 using the spinning current method described above, when the input / output terminals TA, TA ′, TB, TB ′ are alternately switched between the current input terminal pair and the voltage output terminal pair, The region of the current flowing inside is different except for the central part. For this reason, the offset voltage and flicker noise may not be sufficiently removed.
In the Hall element 100 described above, switching elements for switching the four input / output terminals TA, TA ′, TB, TB ′ of the Hall element to be used as current input terminal pairs or voltage output terminal pairs are used. It is necessary to provide a switching circuit including Therefore, since the signal processing circuit that performs signal processing of the Hall element 100 must also control the switching circuit, the circuit configuration of the signal processing circuit may be complicated accordingly.
Therefore, in view of the above problems, the present invention can remove an offset voltage and flicker noise included in an output voltage of a Hall element with a signal processing circuit having a simple circuit configuration in a magnetic sensor having a Hall element. An object is to provide a magnetic sensor.

In order to achieve the above object, an oscillator according to the present invention is configured as follows.
A first magnetic sensor according to the present invention includes a Hall plate having a Hall effect, an input / output terminal formed to be electrically connected to the Hall plate, and at least one of an upper portion and a lower portion of the Hall plate. A Hall element comprising a gate electrode formed through a film, wherein the Hall plate changes the type of carrier moving through the Hall plate to either an electron or a hole depending on the potential of the gate electrode. The input / output terminals are two sets of input / output terminals facing each other in the plane of the hall plate, and one set of input / output terminals is a current. It becomes an input terminal pair, the other input / output terminal is a voltage output terminal pair, and the current input / output terminal pair and the voltage output terminal pair are orthogonal to each other. Characterized in that it is formed at a position.

According to the first magnetic sensor, the hall plate is formed using the bipolar material. For this reason, the polarity of the potential difference output to the voltage output terminal pair can be reversed by changing the carriers moving through the Hall plate to either electrons or holes according to the voltage applied to the gate electrode. However, when the carrier type is changed by the voltage applied to the gate electrode while the magnetic field is applied to the Hall plate, the phase of the potential difference output to the voltage output terminal pair is reversed, but the phase of the offset voltage is not reversed. .
Therefore, the offset voltage and flicker noise included in the potential difference output between the voltage output terminal pair are obtained by taking the difference in potential difference output between the voltage output terminal pair before and after changing the type of carrier moving on the Hall plate. Can be easily removed.

The second magnetic sensor according to the present invention includes a gate voltage control circuit for controlling a gate voltage of the gate electrode.
According to the second magnetic sensor, the gate voltage control circuit can modulate the gate voltage of the gate electrode.

  In a third magnetic sensor according to the present invention, the gate electrode includes a gate electrode formed on an upper portion of the hole plate and a gate electrode formed on a lower portion of the hole plate so as to sandwich the hole plate. The gate voltage control circuit individually controls the gate voltage of the gate electrode formed on the upper part of the Hall plate and the gate voltage of the gate electrode formed on the lower part of the Hall plate. It is characterized by.

According to the third magnetic sensor, the gate voltage control circuit can individually modulate the gate voltages of the two gate electrodes. In addition, the gate voltage control circuit individually controls the voltage of the gate electrode with respect to the potential of the input current terminal electrically connected to the Hall plate and the strength of the electric field perpendicular to the surface of the Hall plate. Is possible.
A fourth magnetic sensor according to the present invention includes a clock generation circuit for generating a clock, the clock generated by the clock generation circuit is input to the gate voltage control circuit, and the gate voltage control circuit is synchronized with the clock. The potential difference output between the voltage output terminal pair is converted into an AC signal by modulating the gate voltage by.

  According to the fourth magnetic sensor, the AC voltage applied to the gate electrode is modulated and output by the clock generated from the clock generation circuit. Thereby, the output voltage output from the Hall element can be converted into an AC signal. By removing the DC component from the potential difference output to the voltage output terminal pair by a filter circuit or the like and extracting only the AC component, the offset voltage and flicker noise can be removed.

The fifth magnetic sensor according to the present invention includes a constant voltage circuit that controls the voltage applied between the pair of current input terminals to be a constant value.
According to the fifth magnetic sensor, the constant voltage circuit can make the voltage applied between the pair of current input terminals constant.

A sixth magnetic sensor according to the present invention includes a constant current circuit that controls a current flowing between the pair of current input terminals to be a constant value.
According to the sixth magnetic sensor, the constant current circuit controls the current flowing through the Hall plate to be a constant value. The offset voltage depends on the current value flowing between the current input terminal pair. However, if the current value flowing between the pair of current input terminals is a constant value, the offset voltage can be made the same regardless of the type of carrier.

A seventh magnetic sensor according to the present invention is characterized in that the hole plate is a graphene layer formed using graphene as a material, and the number of the graphene layers is a single layer or a plurality of layers. To do.
According to the seventh magnetic sensor, the hole plate is formed of a single-layer or multi-layer graphene layer formed using graphene. A single graphene layer is a semiconductor having a zero band gap. Thereby, the polarity of the potential difference output to the voltage output terminal pair can be easily reversed by the voltage applied to the gate electrode. Therefore, the carrier concentration and the current amount with respect to the gate voltage can be made the same before and after the Dirac point where the electron and hole concentrations are equal.

An eighth magnetic sensor according to the present invention is characterized in that the hole plate is a graphene layer formed using graphene as a material, and the number of the graphene layers is two.
According to the eighth magnetic sensor, the hole plate is formed of two graphene layers formed using graphene. In the two graphene layers, a band gap is formed when an electric field is applied in a direction perpendicular to the surface of the graphene layer by two gate electrodes. Thereby, the carrier concentration at the charge neutral point can be reduced. For this reason, it becomes possible to improve the temperature characteristic of the output of a magnetic sensor.

A ninth magnetic sensor according to the present invention is characterized in that the signal processing circuit for performing signal processing of the Hall element and the Hall plate are formed on the same semiconductor substrate.
According to the ninth magnetic sensor, the Hall element as the detection element and the signal processing circuit for performing signal processing of the Hall element are formed on one semiconductor substrate. Thereby, the size of the magnetic sensor can be reduced as compared with the case where the Hall element and the signal processing circuit are formed on separate semiconductor substrates.

  According to the magnetic sensor of the present invention, the offset voltage and flicker noise included in the output voltage of the Hall element can be easily removed with a signal processing circuit having a simpler configuration than the conventional one.

1 is a block diagram showing a circuit configuration of a magnetic sensor 10 according to an embodiment of the present invention. It is a top view when the Hall element 11 which the magnetic sensor 10 which concerns on embodiment of this invention has is seen from the upper surface. 3 is a cross-sectional view illustrating a cross section of the hall element 11 taken along a cross-sectional line AA. FIG. 6 is a graph showing a relationship between a gate voltage Vg applied to a gate electrode G and a current Id flowing between the current input terminal pair TA-TA ′ when a voltage is applied between the current input terminal pair TA-TA ′. FIG. 3 is a schematic diagram showing a schematic structure of the Hall element 100 when a general Hall element 100 is viewed from above.

Hereinafter, preferred embodiments of a magnetic sensor of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(Circuit configuration of the magnetic sensor 10)
First, a circuit configuration of a magnetic sensor 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a circuit configuration of a magnetic sensor 10 according to an embodiment of the present invention.

The magnetic sensor 10 shown in FIG. 1 includes a Hall element 11, a clock generation circuit 12, a gate voltage control circuit 13, a constant voltage circuit 15, a constant current circuit 16, a filter 17, and a demodulation circuit 18. Composed.
Similar to the Hall element 100, the Hall element 11 is a detection element that detects the strength of the magnetic field using the Hall effect.

The clock generation circuit 12 includes a process of modulating the gate voltage output to the Hall element 11 by the gate voltage control circuit 13 and a process of demodulating the output voltage output from the Hall element 11 through the filter 17 by the demodulation circuit 18. Generate a clock to synchronize.
The gate voltage control circuit 13 also serves as a modulation circuit, and modulates the gate voltage of a gate electrode described later in synchronization with the clock generated by the clock generation circuit 12. As a result, the potential difference output between the voltage output terminal pair TB-TB ′ of the Hall element 11 is also modulated.

The constant voltage circuit 15 is configured such that when the gate voltage input to the Hall element 11 is modulated by the gate voltage control circuit 13, the voltage flowing between the input current terminal pair TA-TA ′ of the Hall element 11 becomes a constant value. Control.
The constant current circuit 16 adjusts the current flowing between the input current terminal pair TA-TA ′ of the Hall element 11 to a constant value when the gate voltage input to the Hall element 11 is modulated by the gate voltage control circuit 13. Control. The constant current circuit 16 also controls the value of the gate voltage input to the Hall element 11.

The filter 17 removes the offset voltage (DC component) from the potential difference output between the voltage output terminal pair TB-TB ′ of the Hall element 11 and only the frequency component (AC component) of the modulated AC signal. Extract.
The demodulating circuit 18 demodulates the modulated AC signal in synchronization with the clock generated by the clock generating circuit 12 and outputs a potential difference proportional to the magnetic flux density of the magnetic field applied to the Hall element 11.

  The gate voltage control circuit 13, the constant voltage circuit 15, and the constant current circuit 16 function as a control circuit 19 that controls the operation of the Hall element 11. Further, the clock generation circuit 12, the filter 17, the demodulation circuit 18, and the control circuit 19 function as a signal processing circuit that performs signal processing of the Hall element 11. The Hall element 11 is formed on a semiconductor substrate (not shown) on which the signal processing circuit is formed. The size of the magnetic sensor 10 can be reduced as compared with the case where the Hall element 11 and the signal processing circuit are formed on separate semiconductor substrates.

(Laminated structure of Hall element 11)
Next, a stacked structure of the Hall elements 11 included in the magnetic sensor 10 will be described with reference to FIGS.
FIG. 2 is a top view when the Hall element 11 included in the magnetic sensor 10 according to the embodiment of the present invention is viewed from above. FIG. 3 is a cross-sectional view showing a cross section of the hall element 11 taken along a cross-sectional line AA.

2 and 3 includes a semiconductor substrate 21, an insulating film 22, a hole plate H, a gate electrode G, and input / output terminals TA, TA ′, TB, and TB ′. .
The semiconductor substrate 21 is formed using a material such as silicon (Si) or silicon carbide (SiC). The semiconductor substrate 21 can be formed using a general material used in the manufacture of semiconductor devices, but a silicon substrate formed using silicon is particularly preferable.

  The insulating film 22 is formed using a known material used in manufacturing semiconductor devices such as silicon oxide, silicon nitride, hexagonal boron nitride, alumina, hafnia, zirconia, and yttria. The insulating film 22 is particularly preferably a hexagonal boron nitride insulating film formed using hexagonal boron nitride. The insulating film 22 can be formed using a known manufacturing method used in manufacturing semiconductor devices such as a CVD method or a sputtering method. In order to control the polarity so that the polarity can be reversed with a lower gate voltage, it is preferable to increase the relative dielectric constant and reduce the thickness of the insulating film 22.

  The hall plate H is formed on the semiconductor substrate 21 via the insulating film 22. The Hall plate H is formed using a material having a Hall effect in the same manner as the general Hall element 100. However, the Hall plate H of the Hall element 11 is formed using a bipolar material that can change the type of carriers moving through the Hall plate H to either electrons or holes depending on the potential of the gate electrode. The

  A general Hall element 100 is formed of a semiconductor material. Therefore, the carriers moving through the Hall plate H become electrons when the Hall plate H is an n-type semiconductor, and become holes when the Hall plate H is a p-type semiconductor. Therefore, the phase of the output voltage output from the Hall element 100 when a magnetic field is applied is determined by the type of carrier that moves through the Hall plate H.

However, the Hall plate H of the Hall element 11 is formed of a bipolar material. In this case, the carriers moving through the hole plate H can be changed to either electrons or holes according to the potential of the gate electrode G.
Specific examples of the bipolar material include π-conjugated materials such as graphene and organic semiconductors, and among these, graphene is particularly preferable. For example, graphene composed of carbon is a semiconductor whose energy gap is zero in a single layer. However, in a field effect transistor using graphene as a channel, it is known that carriers induced in the channel have a polarity that becomes electrons or holes depending on the voltage applied to the gate electrode.

  When the hole plate H is formed as a graphene layer using graphene, for example, “W. Zhu, V. Pererbeinos, M. Freitag and P. Avouris: Carrier scattering, mobilities and electrostatic potential in mono-, bi- and tri The hole plate H can be formed by using a well-known manufacturing method used in manufacturing a semiconductor device as described in the document “-layer graphenes: Phys. Rev. B 80, 235402 (2009)”. The graphene layer can be formed of either a single layer or a plurality of layers, but a single layer or a double layer is particularly preferable.

  When the hole plate H is formed of a single graphene layer, the hole plate H is a semiconductor having a zero band gap. Therefore, the graphene layer can reverse the polarity of the potential difference output between the voltage output terminal pair TB-TB ′ by the voltage applied to the gate electrode G. In the graphene layer, the carrier concentration and the current amount with respect to the gate voltage can be made the same before and after the Dirac point where the electron and hole concentrations are equal.

  When the hole plate H is formed of two graphene layers, the hole plate H forms a band gap when an electric field is applied in a direction perpendicular to the surface of the graphene layer by two gate electrodes. Semiconductor. Thereby, the graphene layer can reduce the concentration of carriers at the charge neutral point. For this reason, the temperature characteristics of the output voltage of the magnetic sensor can be improved satisfactorily.

  The input / output terminals TA, TA ′, TB, TB ′ are formed so as to be electrically connected to the Hall plate H. The input / output terminals TA, TA ′, TB, TB ′ are formed using a metal having a relatively small contact resistance with the Hall plate H. The input / output terminals TA, TA ′, TB, TB ′ are preferably formed using a metal, and specifically, Cr, Ni, Ti, Co, Pd, Al, Ag, Cu, Au, Pt, etc. It is particularly preferred to be formed using The input / output terminals TA, TA ', TB, and TB' can be formed by using a known manufacturing method used in manufacturing semiconductor devices such as sputtering, plating, and solder resist screen printing.

  The gate electrode G is formed on the hall plate H with an insulating film 22 interposed therebetween. The gate electrode G is preferably formed using a semiconductor or metal. Specifically, the gate electrode G is formed using Si, Cr, Ni, Ti, Co, Pd, Al, Ag, Cu, Au, Pt, or the like. It is particularly preferable. The gate electrode G can be formed using a well-known manufacturing method used in manufacturing semiconductor devices such as sputtering, CVD, plating, and solder resist screen printing.

  In addition to the gate electrode G above the Hall plate H, the Hall element 11 can cause the semiconductor substrate 21 to function as a gate electrode below the Hall plate H. Accordingly, the gate voltage control circuit 13 individually controls the gate voltages of the portions functioning as the two gate electrodes formed on the upper and lower portions of the Hall plate H. As a result, the gate voltage control is performed on the voltage of the gate electrode with respect to the potential of the current input terminal TA or the current input terminal TA ′ electrically connected to the Hall plate H and the strength of the electric field perpendicular to the surface of the Hall plate H It can be individually controlled by the circuit 13. In addition to the semiconductor substrate 21, another gate electrode may be formed.

(Detection operation of the magnetic sensor 10)
Next, with reference to FIG. 4, the detection operation of the Hall element 11 provided in the magnetic sensor 10 will be described.
FIG. 4 shows the gate voltage Vg applied to the gate electrode G and the current Id flowing between the current input terminal pair TA-TA ′ when a voltage is applied between the current input terminal pair TA-TA ′ of the Hall element 11. It is a graph which shows the relationship.
As shown in the graph of FIG. 4, the potential of the semiconductor substrate 21 that functions in the same way as the gate electrode G has a minimum current Id flowing between the current input terminal pair TA-TA ′ when the gate voltage Vg = 0 (V). It is preferable to become a value. In this case, the semiconductor substrate 21 functions as another gate electrode that sets a charge neutral point. Therefore, the charge neutral point can be shifted by changing the potential of the semiconductor substrate 21.

  Further, as shown in the graph of FIG. 4, when the gate voltage Vg> 0 (V), the current Id flowing between the current input terminal pair TA-TA ′ is mainly due to electrons moving through the Hall plate H due to electrons. It is. Further, when the gate voltage Vg <0 (V), the current Id flowing between the current input terminal pair TA-TA 'is mainly due to the holes moving through the hole plate H due to the holes. The voltage applied between the current input terminal pair TA-TA ′ is fixed, and when the gate voltage Vg> 0 (V), the current Id flowing between the current input terminal pair TA-TA ′ becomes a predetermined current value Ib. The voltage is Vg1. Further, when the gate voltage Vg <0 (V), the gate voltage at which the current Id flowing between the current input terminal pair TA-TA ′ becomes a predetermined current value Ib is defined as Vg2.

In the Hall element 11 shown in FIG. 3, in an ideal state where the offset voltage Voff is zero when a magnetic field having a magnetic flux density B is applied from the upper side to the lower side in FIG. 3, the voltage output terminal pair TB-TB The potential difference Vh output between 'is as follows.
First, when the gate voltage Vg> 0 (V), the potential difference Vh = −Vh1 (V) output between the voltage output terminal pair TB−TB ′. Further, when the gate voltage Vg <0 (V), the potential difference Vh = Vh2 (V) output between the voltage output terminal pair TB-TB ′. At this time, the value of Vh1 (V) and the value of Vh2 (V) have the same sign. Therefore, when the offset voltage Voff exists and the voltage applied between the current input terminal pair TA-TA ′ is a constant value, the offset voltage when the gate voltage Vg> 0 (V) and the gate voltage Vg <0. The offset voltage at (V) is almost the same value.

When the gate voltage Vg> 0 (V), the potential difference Vh + output between the voltage output terminal pair TB−TB ′ can be expressed as the following equation (3). Further, when the gate voltage Vg <0 (V), the potential difference Vh− output between the voltage output terminal pair TB−TB ′ can be expressed as the following equation (4).
Vh + = − Vh1 + Voff (3)
Vh− = Vh2 + Voff ...... Formula (4)

At this time, if the difference between the equation (3) and the equation (4) is taken, the voltage Vh output between the voltage output terminal pair TB-TB ′ is expressed by the following equation (5). ).
Vh = Vh1 + Vh2 (5)
Therefore, the offset voltage Voff can be removed by taking the difference in potential difference output between the voltage output terminal pair TB-TB ′ before and after changing the type of carrier moving on the Hall plate H by the gate voltage Vg.

  Flicker noise is a noise component whose intensity is inversely proportional to the frequency of the output voltage output from the Hall element 11, and is caused by carrier trapping due to a defect in the crystal in the element. Note that the carrier moves through the same hole plate H whether it is an electron or a hole. Therefore, the flicker noise when the gate voltage Vg> 0 (V) and the flicker noise when the gate voltage Vg <0 (V) are substantially the same. Therefore, similarly to the offset voltage Voff, the potential difference corresponding to the magnetic field applied between the voltage output terminal pair TB-TB ′ before and after changing the type of carrier moving the Hall plate H by the gate voltage Vg applied to the gate electrode. The flicker noise can be removed by taking the difference between the two. Note that the frequency of the gate voltage Vg for switching to the gate voltage Vg> 0 (V) or the gate voltage Vg <0 (V) needs to be sufficiently larger than the frequency of flicker noise.

  In the Hall element 11 described in the present embodiment, the four input / output terminals TA, TA ′, TB, and TB ′ are arranged so as to be symmetric four times around the center of the Hall element 11. However, the four-fold symmetry is not essential, and the input / output terminals TB and TB ′ may be arranged so as to be line-symmetric with respect to a straight line passing through the input / output terminal TA and the input / output terminal TATA ′. .

  For example, by changing the arrangement of the input / output terminals to increase the width of current flow, more current flows than the current flowing for the voltage applied between the current input terminal pair TA-TA '. Thereby, since the output voltage output from the Hall element 11 becomes higher, the sensitivity with which the Hall element 11 detects the strength of the magnetic field can be further increased.

  The magnetic sensor of the present invention can be used as a magnetic sensor for detecting the strength of a magnetic field for various electronic devices.

DESCRIPTION OF SYMBOLS 10 ... Magnetic sensor 11 ... Hall element 12 ... Clock generation circuit 13 ... Gate voltage control circuit 15 ... Constant voltage circuit 16 ... Constant current circuit 17 ... Filter 18 ... Demodulation circuit 21 ... Semiconductor substrate 22 ... Insulating film G ... Gate electrode H ... Hall plate TA, TA ', TB, TB' ... Input / output terminal

Claims (9)

A Hall plate having a Hall effect; an input / output terminal formed to be electrically connected to the Hall plate; and a gate electrode formed on at least one of an upper portion or a lower portion of the Hall plate via an insulating film; Comprising a Hall element consisting of
The hole plate is formed using a bipolar material capable of changing the type of carriers moving through the hole plate to either electrons or holes according to the potential of the gate electrode,
The input / output terminals are two sets of input / output terminals facing each other in the plane of the hall plate, and one set of input / output terminals forms a current input terminal pair, and the other set of input / output terminals. Is a voltage output terminal pair, and the current input / output terminal pair and the voltage output terminal pair are formed at positions orthogonal to each other. A gate voltage control circuit for controlling the gate voltage of the gate electrode is provided.
The magnetic sensor according to claim 1. The gate electrode is composed of a gate electrode formed on the top of the hole plate and a gate electrode formed on the bottom of the hole plate so as to sandwich the hole plate,
The gate voltage control circuit individually controls a gate voltage of a gate electrode formed on an upper portion of the Hall plate and a gate voltage of a gate electrode formed on a lower portion of the Hall plate. The magnetic sensor according to claim 2. A clock generation circuit for generating a clock is provided.
A clock generated by the clock generation circuit is input to the gate voltage control circuit, and the gate voltage is modulated by the gate voltage control circuit in synchronization with the clock, so that it is output between the voltage output terminal pair. The potential difference is converted into an AC signal,
The magnetic sensor according to any one of claims 1 to 3. It comprises a constant voltage circuit for controlling the voltage applied between the current input terminal pair to be a constant value,
The magnetic sensor according to any one of claims 1 to 4. It comprises a constant current circuit for controlling the current flowing between the current input terminal pair to be a constant value,
The magnetic sensor according to any one of claims 1 to 5. The hole plate is a graphene layer formed using graphene as a material, wherein the number of the graphene layers is a single layer or a plurality of layers.
The magnetic sensor according to claim 1. The hole plate is a graphene layer formed using graphene as a material, and the number of the graphene layers is two.
The magnetic sensor according to claim 7. The signal processing circuit for performing signal processing of the Hall element and the Hall plate are formed on the same semiconductor substrate,
The magnetic sensor according to claim 1.

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