JP2015078949A - Hall electromotive force signal detection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Hall electromotive force addition/subtraction circuit in which characteristics deterioration of a Hall element due to a substrate bias effect is reduced.SOLUTION: First and second Hall elements 11, 12 include a first terminal, a second terminal, a third terminal and a fourth terminal. A first amplifier 31 includes: an inverted input terminal connected to the first terminal of the first Hall element 11; a non-inverted input terminal connected to a common voltage; and an output terminal connected to the second terminal of the first Hall element 11. A second amplifier 32 includes: an inverted input terminal connected to the third terminal of the second Hall element 12; a non-inverted input terminal connected to a common voltage; and an output terminal connected to the second terminal of the second Hall element 12. An output is detected from the third terminal of the first Hall element 11 and the first terminal of the second Hall element 12.

Description

  The present invention relates to a Hall electromotive force signal detection circuit for adding and subtracting Hall electromotive force, and more particularly to a Hall electromotive force signal detection circuit that significantly reduces the influence of characteristic deterioration of a Hall element due to a substrate bias effect factor.

Conventionally, magnetic sensors using Hall elements are not only used for proximity sensors, linear position sensors, rotation angle sensors, etc., as sensors for detecting magnet position information, but also induced by current flowing through a current conductor. It is also widely used in applications of current sensors that measure the amount of current flowing through a current conductor in a non-contact manner by detecting magnetic fields.
In particular, in a current sensor used for detecting an inverter current of a motor, it is required to detect an inverter current switching at a high frequency with high accuracy for the purpose of improving the efficiency of motor control.

This type of Hall element is widely used as a magnetic sensor because it has a magnetoelectric conversion function for generating a Hall electromotive force signal corresponding to the intensity of an input magnetic field. However, the Hall element has an offset voltage (unbalanced voltage) in which a finite voltage that is not zero is output even in a state where the magnetic field is zero, that is, in a state where there is no magnetic field.
Therefore, in a magnetic sensor using a Hall element, for the purpose of canceling an offset voltage possessed by the Hall element, a Hall element driving method generally known by a name such as a spinning current method or a Connection comment method is used. Exists. This method is an operation of periodically switching between the position of a terminal pair for flowing a drive current to the Hall element and the position of a terminal pair for detecting a Hall electromotive force signal according to a clock called a chopper clock. (For example, see Non-Patent Document 1 and Patent Document 1)
Hereinafter, the Spinning current method of the Hall element will be described based on FIGS. 1A and 1B (see, for example, Patent Document 2).

FIGS. 1A and 1B show a case where the direction of the drive current for biasing the Hall element is switched between 0 degree and 90 degrees each time the phase of the chopper clock is switched between two values of φ1 and φ2. It is a figure explaining the Hall electromotive force detection of.
The Hall element in the figure is modeled as a four-terminal element composed of four resistors (R1, R2, R3, R4), and is driven at a constant current.

  In the Hall element model shown in FIGS. 1A and 1B, it should be noted that the resistance values of these four resistors (R1, R2, R3, R4) are not fixed values. When the Hall element is formed as an N-well in a semiconductor substrate, an impurity concentration distribution is generally generated inside each Hall element due to a process gradient during semiconductor manufacturing. For this reason, the potential distribution in the Hall element (N well) varies depending on which of the four terminals (terminal 1, terminal 2, terminal 3, and terminal 4) the drive current is injected into, so that the Hall element (N The occurrence of depletion layers inside the wells also changes. Accordingly, the resistance values of the four resistors R1, R2, R3, and R4 in the Hall element model are such that the driving current is injected from any of the four terminals (terminal 1, terminal 2, terminal 3, and terminal 4) of the Hall element. Depending on whether or not, each value will change.

  1A and 1B, measurement is performed when the phase of the chopper clock is φ1 (the driving direction of the Hall element is 0 degrees) and when the phase of the chopper clock is φ2 (the driving direction of the Hall element is 90 degrees). The voltage signals Vhall (φ1) and Vhall (φ2) to be generated are the Hall electromotive force signal Vsig (B) and the Hall corresponding to the magnetic field B to be detected by the magnetic sensor using the Hall element as shown in the following Equation 1. It is expressed as the sum of the offset voltage Vos (Hall) of the element.

  Here, the polarity of the Hall electromotive force signal Vsig (B) corresponding to the magnetic field to be detected by periodically switching the bias current direction of the Hall element between 0 degree and 90 degrees according to the phase of the chopper clock. Since Vsig (B) can be frequency-modulated to the frequency f_chop of the chopper clock.

On the other hand, the DC offset voltage Vos (Hall) of the Hall element has the same polarity value even if the driving direction of the Hall element is switched between 0 degrees and 90 degrees, so Vos (Hall) is the frequency of the chopper clock. Not modulated.
From the above, when the operation of switching the direction of the driving current of the Hall element between 0 degree and 90 degrees according to the phase of the chopper clock is performed, the signal Vhall generated in the Hall element is as shown in FIG. The waveform is as shown in (d). Since the spectrum of the signal generated in the Hall element is a spectrum as shown in FIG. 3, the Hall electromotive force signal Vsig (B) corresponding to the magnetic field to be detected and the offset voltage Vos (Hall) of the Hall element. Are separated in the frequency domain. This is the principle of the offset cancellation of the Hall element by the spinning current method.

  FIG. 4 is a circuit configuration diagram for explaining a conventional Hall electromotive force signal detection circuit, and shows an example of a circuit that connects two Hall elements and adds the signals. In the figure, reference numeral 1 denotes a chopper clock generation circuit, 2 denotes a drive current generation circuit, 3 denotes a first Hall element, 4 denotes a first switch circuit, 5 denotes a second Hall element, 6 denotes a second switch circuit, 7 Indicates a Hall electromotive force signal adding circuit.

In the Hall electromotive force signal detection circuit shown in FIG. 4, Hall electromotive force signals Vhall1 and Vhall2 generated in the first Hall element 3 and the second Hall element 5 which are two Hall elements are added to the Hall electromotive force signal adding circuit 7. To generate an output signal Vhall_sum12.
Each of the first Hall element 3 and the second Hall element 5 includes four terminals (terminal 1, terminal 2, terminal 3, and terminal 4), and the first Hall element 3 and the second Hall element. In the first switch circuit 4 and the second switch circuit 6 connected to each of the circuit 5, according to the phase φ (φ1, φ2) of the two-phase chopper clock signal generated in the chopper clock generation circuit 1, By switching between a terminal pair for injecting a drive current for driving the element and a terminal pair for detecting the Hall electromotive force signal, Hall electromotive force signals Vhall1 and Vhall2 generated in the first Hall element 3 and the second Hall element 5, respectively. Is detected. In other words, the first Hall element 3 and the second Hall element 5 are each subjected to offset cancellation by the spinning current method.

  The Hall electromotive force signals Vhall1 and Vhall2 described above are added by the Hall electromotive force signal adding circuit 7 to obtain an output signal Vhall_sum12.

U.S. Pat. No. 4,435,653 (A) JP 2013-178229 A

R S Popovic, Hall Effect Devices (ISBN-10: 0750300965) Inst of Physics Pub, Inc. , (1991/05)

However, in the configuration as shown in FIG. 4, the output common voltage of the Hall electromotive force varies depending on the operating temperature. This is because, as shown in FIG. 5, the output common voltage (Vcom) of the Hall electromotive force greatly varies due to the temperature variation of the Hall element resistance.
As a result of fluctuations in the output common voltage of the Hall electromotive force, the magnetic sensitivity of the Hall element fluctuates not only due to the characteristic of the Hall element, but also due to the substrate bias effect, resulting in nonlinearity in the temperature characteristic of the output sensitivity. .

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a Hall electromotive force signal detection circuit that significantly reduces the influence of Hall element characteristic deterioration due to a substrate bias effect factor. There is to do.

The present invention has been made to achieve such an object. The invention according to claim 1 is a first terminal having a first terminal, a second terminal, a third terminal, and a fourth terminal. Hall element (11), a second Hall element (12) having a first terminal, a second terminal, a third terminal and a fourth terminal, and the first Hall element (11) 4, a current source (21, 22) for causing a drive current to flow to the fourth terminal of the second Hall element (12), and an inverting input terminal (−) include the first Hall element (11). A first amplifier having a non-inverting input terminal (+) connected to a common voltage and an output terminal connected to a second terminal of the first Hall element (11). (31) and an inverting input terminal (−) are connected to a third terminal of the second Hall element (12), and a non-inverting input terminal ( ) Is connected to a common voltage, and an output terminal includes a second amplifier (32) connected to a second terminal of the second Hall element (12). It is a power signal detection circuit. (FIG. 6; Example 1)
According to a second aspect of the present invention, in the first aspect of the present invention, the current source (21, 22) supplies a driving current to the fourth terminal of the first Hall element (11). 1 current source (21) and a second current source (22) for flowing a drive current to the fourth terminal of the second Hall element (12).

According to a third aspect of the present invention, in the first or second aspect of the present invention, the third terminal of the first Hall element (11) and the first terminal of the second Hall element (12) are provided. The output is detected from the terminal.
According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, the chopper clock generation circuit (51) that generates a chopper clock signal and the first circuit according to the chopper clock signal are provided. A first switch circuit (41) for switching the connection of each terminal of the Hall element (11) and a second switch circuit (for switching the connection of each terminal of the second Hall element (12) in accordance with the chopper clock signal) 42), each terminal of the first Hall element (11), and the first amplifier (31) and the first current source (21) are connected to the first switch circuit (41). Each terminal of the second Hall element (12), the second amplifier (32) and the second current source (22) are connected to each other by the second switch circuit (42). Connected through And said that you are. (FIG. 7; Example 2)
According to a fifth aspect of the present invention, in the first, second, or third aspect of the invention, each terminal of the first Hall element (11) is a first terminal and a fourth terminal clockwise. And the third terminal and the second terminal are switched in this order, and each terminal of the second Hall element (12) is counterclockwise, the first terminal, the second terminal, the third terminal, and the fourth terminal It is characterized by switching in the order of terminals. (Fig. 9)

According to a sixth aspect of the present invention, in the first, second, or third aspect of the present invention, each terminal of the first Hall element (11) includes a first terminal, a second terminal, and a fourth terminal. The terminal of the second Hall element (12) is switched in the order of the fourth terminal, the third terminal, the first terminal, and the second terminal. It is characterized by. (Fig. 10)
According to a seventh aspect of the present invention, in the first, second or third aspect of the present invention, the direction of the magnetic field input to the first Hall element (11) and the second Hall element (12). Are arranged in the opposite direction, and each terminal of the first Hall element (11) is arranged in a clockwise direction with a first terminal, a second terminal, a third terminal, and a fourth terminal. The terminals of the second Hall element (12) are arranged in a counterclockwise direction with a first terminal, a second terminal, a third terminal, and a fourth terminal. (FIG. 11; Example 3)

  The invention according to claim 8 is the invention according to claim 1, wherein the third Hall element (13) having the first terminal, the second terminal, the third terminal, and the fourth terminal is provided. A fourth Hall element (14) having a first terminal, a second terminal, a third terminal, and a fourth terminal, a fourth terminal of the first Hall element (11), and the first terminal Current flowing through the fourth terminal of the second Hall element (12), the fourth terminal of the third Hall element (13), and the fourth terminal of the fourth Hall element (14) A source (21, 22, 23, 24) and an inverting input terminal (−) are connected to a first terminal of the third Hall element (13), and a non-inverting input terminal (+) is connected to the first terminal. A third terminal connected to the third terminal of the third Hall element (11) and an output terminal connected to the second terminal of the third Hall element (13). An amplifier (33) and an inverting input terminal (−) are connected to a third terminal of the fourth Hall element (14), and a non-inverting input terminal (+) is connected to the second Hall element (12). A fourth amplifier (34) connected to a second terminal of the fourth Hall element (14) and having an output terminal connected to a second terminal of the fourth Hall element (14), and the third Hall element (13 ) And the first terminal of the fourth Hall element (14) to detect the output. (FIG. 12; Example 4)

  According to a ninth aspect of the invention, in the eighth aspect of the invention, the current source (21, 22, 23, 24) is driven to a fourth terminal of the first Hall element (11). A first current source (21) for supplying current, a second current source (22) for supplying a drive current to the fourth terminal of the second Hall element (12), and the third Hall element (13). ) Of the fourth terminal of the fourth Hall element (14) and a fourth current source (24) of the fourth Hall element (14). It is characterized by that.

According to the present invention, by maintaining the output common voltage of the Hall electromotive force constant, it is possible to remarkably reduce characteristic deterioration (for example, non-linearity of temperature characteristics of magnetic sensitivity) due to the variation factor of the substrate bias effect of the Hall element. Become.
Further, addition / subtraction of a plurality of Hall electromotive force signals can be realized only by the drive circuit. That is, magnetic fields having different polarities and magnitudes can be detected, and the signals can be added and subtracted. For example, it can be suitably used for detecting a transverse magnetic field using a magnetic converging plate.

(A) and (b) show the holes when the direction of the drive current for biasing the Hall element is switched between 0 degrees and 90 degrees each time the phase of the chopper clock is switched between two values of φ1 and φ2. It is a figure explaining electromotive force detection. (A) thru | or (d) is a figure which shows the signal waveform which generate | occur | produces in the Hall element shown in FIG. It is a figure which shows the signal spectrum of signal Vhall which generate | occur | produces in a Hall element. It is a circuit block diagram for demonstrating the conventional Hall electromotive force signal detection circuit. It is a figure for demonstrating that the output common voltage of Hall electromotive force output changes with temperature in FIG. It is a circuit block diagram for demonstrating Example 1 of the Hall electromotive force signal detection circuit based on this invention. It is a circuit block diagram for demonstrating Example 2 of the Hall electromotive force signal detection circuit based on this invention. In (a) to (d), when the phase φ of the chopper clock is switched between φ1, φ2, φ3, and φ4 in the first Hall element and the second Hall element, the drive current of the Hall element is energized. It is the figure shown about two terminals and two terminals which detect a Hall electromotive force signal. FIG. 9 is a circuit configuration diagram for explaining a driving method in Embodiment 2 of the Hall electromotive force signal detection circuit according to the present invention shown in FIG. 7. FIG. 9 is a circuit configuration diagram for explaining another driving method in Embodiment 2 of the Hall electromotive force signal detection circuit according to the present invention shown in FIG. 7. It is a circuit block diagram for demonstrating Example 3 of the Hall electromotive force detection circuit based on this invention. It is a circuit block diagram for demonstrating Example 4 of the Hall electromotive force detection circuit based on this invention. It is the figure which showed the relationship between temperature and Hall electromotive force common voltage.

  First, the output common voltage of the Hall electromotive force, which is a premise of the present invention, will be described below with reference to FIG. In this configuration, the drive current is supplied from the terminal 2 biased to Vref to the terminal 4 connected to the drive current generation circuit 2, so that the potential difference between the terminal 1 and the terminal 3 is detected as the Hall electromotive force. Is. The Hall element 1 includes first to fourth terminals and generates a Hall electromotive force signal voltage Vhall.

  When the Hall element is formed as an N-type semiconductor and the direction of the magnetic field B applied to the Hall element 1 is a direction perpendicular from the back side surface to the front side surface of the paper surface, between the terminal 2 and the terminal 4 The generated Hall electromotive force signal is generated as a voltage signal having a positive potential + Vsig (B) at the terminal 2 and a negative potential -Vsig (B) at the terminal 4. Therefore, since the Hall electromotive force signal Vhall1 is defined as the potential of the terminal 2 measured with respect to the terminal 4, the Hall electromotive force signal Vhall1 generated in the Hall element 1 is detected as + 2Vsig (B). become.

In FIG. 1A, when each bridge resistance of the Hall element is Rh, the driving current is Id, and the driving voltage is Vd, the Hall electromotive force common voltage Vc (= (Vhall (+) − Vhall (−)) / 2) is represented by the following formula.
Vc = Vd−Rh · Id / 2
Here, assuming that Vd and Id are constant regardless of the temperature, and Rh (= R1 = R2 = R3 = R4) depends on the temperature T, the common voltage Vc varies with the temperature T.

The fact that the common voltage Vc fluctuates means that the substrate bias Vb of the Hall element fluctuates. Further, when the substrate bias Vb changes, the depletion layer formed in the well of the Hall element changes, and the sensitivity S of the Hall element also changes.
In summary, it can be seen that the sensitivity S varies as the common voltage Vc varies.

[Embodiment]
Hereinafter, embodiments of the Hall electromotive force signal detection circuit according to the present invention will be described.
The Hall electromotive force signal detection circuit according to the present embodiment includes a first Hall element having a first terminal, a second terminal, a third terminal, and a fourth terminal, a first terminal, a second terminal, A second Hall element having a third terminal and a fourth terminal; a fourth terminal of the first Hall element; and a current source for passing a drive current to the fourth terminal of the second Hall element. ing.
It is preferable that the first terminal and the third terminal face each other, and the second terminal and the fourth terminal face each other. In addition, it is preferable that the second terminal, the third terminal, and the fourth terminal are arranged clockwise or counterclockwise by 90 degrees in order from the first terminal. In addition, you may have a terminal. The current source may be provided for each Hall element or may be shared.

  In the Hall electromotive force signal detection circuit of the present embodiment, the inverting input terminal is connected to the first terminal of the first Hall element, the non-inverting input terminal is connected to the common voltage, and the output terminal is connected to the first terminal. A first amplifier connected to a second terminal of one Hall element, an inverting input terminal connected to a third terminal of the second Hall element, a non-inverting input terminal connected to a common voltage, The output terminal includes a second amplifier connected to the second terminal of the second Hall element. Examples of the amplifier include an operational amplifier.

With such a configuration, since the first terminal of the first Hall element and the third terminal of the second Hall element have a common voltage, the output common voltage of the Hall element is kept constant.
Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 is a circuit configuration diagram for explaining the first embodiment of the Hall electromotive force signal detection circuit according to the present invention. In the figure, reference numeral 11 denotes a first Hall element, 12 denotes a second Hall element, 21 denotes a first drive current generation circuit, 22 denotes a second drive current generation circuit, 31 denotes a first operational amplifier (amplifier), 32 Indicates a second operational amplifier (amplifier).
The first Hall element 11 has a first terminal, a second terminal, a third terminal, and a fourth terminal. The second Hall element 12 has a first terminal, a second terminal, a third terminal, and a fourth terminal.

In addition, the current sources 21 and 22 are configured to flow drive currents to the fourth terminal of the first Hall element 11 and the fourth terminal of the second Hall element 12, respectively.
The first amplifier 31 has an inverting input terminal (−) connected to the first terminal of the first Hall element 11 and a non-inverting input terminal (+) connected to the common voltage (Vcom). The output terminal is connected to the second terminal of the first Hall element 11.

The second amplifier 32 has an inverting input terminal (−) connected to the third terminal of the second Hall element 12, a non-inverting input terminal (+) connected to the common voltage, and an output terminal The second Hall element 12 is connected to the second terminal.
The current sources 21 and 22 include a first current source 21 that supplies a drive current to the fourth terminal of the first Hall element 11 and a first current source 21 that supplies a drive current to the fourth terminal of the second Hall element 12. Two current sources 22 are provided. Further, the output is detected from the third terminal of the first Hall element 11 and the first terminal of the second Hall element 12.

That is, in the first embodiment, the Hall electromotive force Vhall1 generated by supplying a drive current to the first Hall element 11 and the Hall electromotive force Vhall2 generated by supplying a drive current to the second Hall element 12 are used. Is configured to detect the voltage (Vhall) added.
The first Hall element (one Hall element) 11 includes first to fourth terminals and generates one Hall electromotive force signal voltage Vhall1.

The second Hall element (the other Hall element) 12 includes first to fourth terminals and generates one Hall electromotive force signal voltage Vhall2.
Each Hall element may have a plurality of Hall elements connected in parallel.
The first and second Hall drive current generation circuits 21 and 22 supply drive currents to the first and second Hall elements 11 and 12, respectively.

The first operational amplifier 31 applies negative feedback so that the terminal 1 of the first Hall element 11, that is, one terminal generating the Hall electromotive force is equal to the voltage Vcom supplied from the common voltage output circuit. It adjusts the output voltage (voltage at terminal 2).
The second operational amplifier 32 applies negative feedback so that the terminal 3 of the second Hall element 12, that is, one terminal generating the Hall electromotive force is equal to Vcom, and outputs the output voltage (voltage of the terminal 2). To be adjusted.

  Table 1 summarizes terminal pairs for detecting Hall electromotive force signals and Hall electromotive force signals Vhall1, Vhall2, and Vhall in the first Hall element 11 and the second Hall element 12.

  Here, the first Hall element and the second Hall element are two different Hall elements, but it is assumed that the magnetic sensitivity values are uniform between the first Hall element second and the Hall element. Thus, the common value Vsig (B) is used between the first Hall element and the second Hall element. With respect to this assumption, if the first Hall element and the second Hall element are formed using a semiconductor IC process and are arranged close to each other in the IC, the first Hall element and the second Hall element On the other hand, this assumption is a reasonable assumption because the process gradient at the time of manufacturing the semiconductor uniformly extends.

  The point to be particularly noted in the circuit shown in FIG. 6 is that the output common voltage of the Hall element is always kept at Vcom regardless of the fluctuation of the resistance Rh of the Hall element bridge model. Therefore, in this configuration, since the substrate bias effect of the Hall element is kept constant regardless of the variation of Rh, the variation of the sensitivity S originating from the substrate bias effect of the Hall element is compared with the configuration of FIG. In particular, the temperature characteristics can be significantly reduced. Table 2 shows the Hall electromotive force and the output common voltage of each Hall element.

  According to Table 2, when a magnetic field is applied to the Hall element, Hall electromotive force is generated, so that the output common voltage of the first Hall element 11 is not Vcom but Vcom-Vsig (B), and the substrate bias effect varies. Resulting in. However, since the output common voltage of the second Hall element 12 is Vcom + Vsig (B), the primary component depending on the substrate bias Vb of the sensitivity S is canceled out.

Assuming that the component of the sensitivity S that depends on the substrate bias Vb is only the first order, and considering its influence, the sensitivity S of the Hall element is expressed as S (1 + α · ΔVb). Here, ΔVb represents a change in Vb from the no magnetic field input state, and α represents a constant coefficient thereof.
When the magnetic field B is applied, from Table 2, the sensitivity S1 of the first Hall element is S (1−α · Vsig (B)), and the sensitivity S2 of the second Hall element is S (1 + α · Vsig ( B)) respectively. And since the whole sensitivity becomes the sum of each sensitivity, it becomes S1 + S2 = 2S, and the sensitivity can be kept constant irrespective of the applied magnetic field. For this reason, deterioration of the output linearity of sensitivity is not a problem.

Although it is assumed that the sensitivity S has only a primary component that depends on Vb, the actual Hall electromotive force is a very small value of about several mV to several tens of mV, so the primary component is almost dominant. This assumption is a reasonable assumption.
According to the first embodiment, as shown in FIG. 13, since the common voltage of the Hall electromotive force can be kept constant regardless of the temperature, it is possible to significantly reduce the influence of the back bias effect. In addition, since the common voltage is constant, there is an advantage that the input range of the subsequent circuit may be narrow, and a design with a higher degree of freedom is possible.

FIG. 7 is a circuit configuration diagram for explaining Example 2 of the Hall electromotive force signal detection circuit according to the present invention. In the figure, reference numeral 41 denotes a first switch circuit, 42 denotes a second switch circuit, and 51 denotes a chopper clock generation circuit. In addition, the same code | symbol is attached | subjected to the component which has the same function as FIG.
The difference from the first embodiment shown in FIG. 6 is that the second embodiment includes a switch circuit and a chopper clock generation circuit. Below, a different point from Example 1 mentioned above is demonstrated.

The Hall electromotive force signal detection circuit of the second embodiment is configured to detect a Hall electromotive force signal voltage by selecting a terminal position through which a drive current is supplied to the Hall elements 11 and 12 having a plurality of terminals. It is a power signal detection circuit.
The Hall electromotive force signal detection circuit according to the second embodiment includes a chopper clock generation circuit 51, a first switch circuit 41, and a second switch circuit 42. The chopper clock generation circuit 51 generates a chopper clock signal.

The first switch circuit 41 switches the connection of each terminal of the first Hall element 11 according to the chopper clock signal. The second switch circuit 42 switches the connection of each terminal of the second Hall element 12 according to the chopper clock signal.
Each terminal of the first Hall element 11 is connected to the first amplifier 31 and the first current source 21 via the first switch circuit 41, and each terminal of the second Hall element 12 is connected to the first Hall element 11. The second amplifier 32 and the second current source 22 are connected via a second switch circuit 42.

  The first and second switch circuits 41 and 42 switch the connection of each terminal of the Hall element according to the clock signal supplied from the chopper clock generation circuit. That is, the spinning current method is realized by switching two or more phases. There is no need for such a switch circuit, but a more accurate Hall electromotive force detection circuit can be realized by combining with the Spinning current method.

FIGS. 8A to 8D show two cases in which the driving current of the Hall element is supplied when the phase φ of the chopper clock is switched between φ1 and φ2 in the first Hall element and the second Hall element. It is the figure shown about two terminals which detect a terminal and a Hall electromotive force signal.
8A to 8D, it is possible to detect the Hall electromotive force with higher accuracy by combining the Spinning current method while keeping the output common voltage constant and suppressing the fluctuation due to the back bias effect. .

<0 ° -90 ° chopper>
By repeating FIG. 8A at the chopper clock phase φ1 and FIG. 8B at φ2, it is possible to cancel the offset by driving the chopper while keeping the output common voltage constant. Any driving method may be used as long as the driving has a phase difference of 90 ° between φ1 and φ2. For example, the driving direction of the Hall elements 11 and 12 may be rotated or the relative angle may be changed. In addition, since the chopper driving for the transition of the driving direction to be opposite to each other is combined between the two Hall elements 11 and 12, it is possible to cancel the spike at the time of chopper switching.

<0 ° -90 ° -180 ° -270 ° chopper>
By repeating FIG. 8 (a) at the chopper clock phase φ1, FIG. 8 (b) at φ2, FIG. 8 (c) at φ3, and FIG. 8 (d) at φ4, the output common voltage is made constant and the chopper driving is performed. Offset cancellation is possible. At this time, the Hall elements 11 and 12 are chopper driven clockwise and counterclockwise, respectively.

  In addition, according to the second embodiment, 360 ° chopper driving is performed, so that the offset of the Hall element can be canceled with higher accuracy. Further, since the reverse chopper drive is combined with the two Hall elements 11 and 12, it is possible to cancel the spike at the time of chopper switching. Any driving method may be used as long as it is a combination of clockwise driving and counterclockwise driving. For example, the driving directions of the Hall elements 11 and 12 may be rotated or the relative angles may be changed.

<0 ° -90 ° -270 ° -180 ° chopper>
By repeating FIG. 8 (a) at the chopper clock phase φ1, FIG. 8 (b) at φ2, FIG. 8 (d) at φ3, and FIG. 8 (c) at φ4, the output common voltage is made constant and the chopper driving is performed. Offset cancellation is possible. At this time, the first Hall element 11 is chopper-driven in the order of 8 in the order of 0 ° for φ1, 90 ° for φ2, 270 ° for φ3, and 180 ° for φ4, and the second Hall element 12 is φ1 The chopper is driven in the reverse direction of the figure 8 in the order of 270 ° at φ2, 180 ° at φ2, 0 ° at φ3, and 90 ° at φ4.

  In addition, according to the second embodiment, 360 ° chopper driving is performed, so that the offset of the Hall element can be canceled with higher accuracy. Further, since the reverse chopper drive is combined with the two Hall elements 11 and 12, it is possible to cancel the spike at the time of chopper switching. Any driving method may be used as long as it is a combination of driving in the shape of figure 8 and driving in the opposite direction. For example, the driving directions of the Hall elements 11 and 12 may be rotated or the relative angle may be changed. Absent.

FIG. 9 is a circuit configuration diagram for explaining a driving method in Embodiment 2 of the Hall electromotive force signal detection circuit according to the present invention shown in FIG.
The terminals of the first Hall element 11 are switched in the order of the first terminal, the fourth terminal, the third terminal, and the second terminal in the clockwise direction, and the terminals of the second Hall element 12 are switched to the left. The first terminal, the second terminal, the third terminal, and the fourth terminal are sequentially switched around. That is, this is a driving method in which clockwise driving and counterclockwise driving are combined.

FIG. 10 is a circuit configuration diagram for explaining another driving method in the second embodiment of the Hall electromotive force signal detection circuit according to the present invention shown in FIG.
Each terminal of the first Hall element 11 is switched in the order of the first terminal, the second terminal, the fourth terminal, and the third terminal, and each terminal of the second Hall element 12 is switched to the first terminal. And the second terminal, the fourth terminal, and the third terminal. In other words, this is a driving method that combines driving around the figure 8 and driving in the opposite direction.

  FIG. 11 is a circuit configuration diagram for explaining Example 3 of the Hall electromotive force signal detection circuit according to the present invention. The circuit configuration of FIG. 6 is different from that of FIG. 6 in that the connection between the first terminal and the third terminal, which are the Hall electromotive force output terminals of the first Hall element 11, is switched. The polarity of the Hall electromotive force output from each of 11 and the second Hall element 12 is opposite. In addition, a reverse magnetic field is applied to the first Hall element 11 and the second Hall element 12.

  That is, the configuration of FIG. 11 includes a magnetic convergence plate 15 in which the directions of the magnetic fields input to the first Hall element 11 and the second Hall element 12 are opposite, and each terminal of the first Hall element is The first terminal, the second terminal, the third terminal, and the fourth terminal are arranged clockwise, and each terminal of the second Hall element is arranged counterclockwise with the first terminal, the second terminal, and the second terminal. 3 is a Hall electromotive force signal detection circuit arranged with a third terminal and a fourth terminal.

The circuit configuration of FIG. 11 can obtain the addition result without canceling each Hall electromotive force even when a magnetic field in the opposite direction is applied to each Hall element. Can be used for magnetic field detection.
When the magnetic converging plate 15 is used, for example, the first Hall element 11 and the second Hall element 11 and the second Hall element 12 are provided with separate magnetic convergence plates. Since the direction of the magnetic field applied to the element 12 is reversed, the circuit configuration in FIG. 11 is connected so that the polarity of the Hall electromotive force is reversed.

  Also in the third embodiment, the output common voltage can be kept constant, the fluctuation of the back bias effect can be suppressed, and the linearity of sensitivity can be improved.

FIG. 12 is a circuit configuration diagram for explaining a fourth embodiment of the Hall electromotive force signal detection circuit according to the present invention. In the figure, reference numeral 13 is a third Hall element, 14 is a fourth Hall element, 23 is a third drive current generation circuit, 24 is a fourth drive current generation circuit, 33 is a third operational amplifier, and 34 is a fourth operation element. Shows an operational amplifier.
The Hall electromotive force signal detection circuit according to the fourth embodiment includes a third Hall element 13, a fourth Hall element 14, current sources 21, 22, 23, 24, a third amplifier 33, and a fourth amplifier 34. I have.

The third Hall element 13 has a first terminal, a second terminal, a third terminal, and a fourth terminal. The fourth Hall element 14 has a first terminal, a second terminal, a third terminal, and a fourth terminal.
The current sources 21, 22, 23, and 24 include a fourth terminal of the first Hall element 11, a fourth terminal of the second Hall element 12, and a fourth terminal of the third Hall element 13. Then, a drive current is passed through the fourth terminal of the fourth Hall element 14.

  In the third amplifier 33, the inverting input terminal (−) is connected to the first terminal of the third Hall element 13, and the non-inverting input terminal (+) is the third terminal of the first Hall element 11. The output terminal is connected to the second terminal of the third Hall element 13. In the fourth amplifier 34, the inverting input terminal (−) is connected to the third terminal of the fourth Hall element 14, and the non-inverting input terminal (+) is the first of the second Hall element 12. The output terminal is connected to the second terminal of the fourth Hall element 14. Further, the output is detected from the third terminal of the third Hall element 13 and the first terminal of the fourth Hall element 14.

  The current sources 21, 22, 23, and 24 are driven to the first current source 21 that supplies a drive current to the fourth terminal of the first Hall element 11 and the fourth terminal of the second Hall element 12. A second current source 22 for passing current, a third current source 23 for passing drive current to the fourth terminal of the third Hall element 13, and a drive current for the fourth terminal of the fourth Hall element 14 And a fourth current source 24 for flowing.

  That is, the Hall electromotive force signal detection circuit according to the fourth embodiment applies a Hall electromotive force Vhall1 generated by supplying a drive current to the first Hall element 11 and a drive current to the second Hall element 12. Of the Hall electromotive force Vhall2 generated by applying the drive current to the third Hall element 13, and the Hall electromotive force Vhall4 generated by supplying the drive current to the fourth Hall element 14. The added voltage (Vhall) is detected.

The first Hall element 11 includes first to fourth terminals and generates one Hall electromotive force signal voltage Vhall1. The second Hall element 12 includes first to fourth terminals and generates one Hall electromotive force signal voltage Vhall2.
The third Hall element 13 includes first to fourth terminals and generates one Hall electromotive force signal voltage Vhall3. The fourth Hall element 14 includes first to fourth terminals and generates one Hall electromotive force signal voltage Vhall4.

Each Hall element may have a plurality of Hall elements connected in parallel. The first to fourth Hall drive current generation circuits 21, 22, 23, and 24 supply drive currents to the first to fourth Hall elements 11, 12, 13, and 14, respectively.
The first operational amplifier 31 applies negative feedback so that the terminal 1 of the first Hall element 11, that is, one terminal that generates the Hall electromotive force is equal to Vcom, and outputs the output voltage (voltage of the terminal 2). To be adjusted.

The second operational amplifier 32 applies negative feedback so that the terminal 3 of the second Hall element 12, that is, one terminal generating the Hall electromotive force is equal to Vcom, and outputs the output voltage (voltage of the terminal 2). To be adjusted.
The third operational amplifier 33 applies negative feedback so that the terminal 1 of the third Hall element 13, that is, one terminal that generates the Hall electromotive force is equal to the potential of the terminal 3 of the first Hall element 11. The output voltage (the voltage at the terminal 2 of the third Hall element) is adjusted.

The fourth operational amplifier 34 applies negative feedback so that the terminal 3 of the fourth Hall element 14, that is, one terminal that generates the Hall electromotive force is equal to the potential of the terminal 1 of the second Hall element 12. The output voltage (the voltage at the terminal 2 of the fourth Hall element) is adjusted.
By adding the Hall electromotive force in series with the circuit configuration shown in FIG. 12, a larger Hall electromotive force can be obtained as an output. FIG. 12 shows an example in which four Hall electromotive forces are added in series, but it goes without saying that a larger number may be connected.

  Further, as shown in FIG. 12, the first Hall element, the second Hall element, the third Hall element, and the fourth Hall element are added in series. The Hall elements may be added in series, the third Hall element and the fourth Hall element may be added in series, and their outputs may be calculated in the subsequent stage.

DESCRIPTION OF SYMBOLS 11 1st Hall element 12 2nd Hall element 13 3rd Hall element 14 4th Hall element 15 Magnetic converging plate 21 1st drive current generation circuit 22 2nd drive current generation circuit 23 3rd drive current Generation circuit 24 Fourth drive current generation circuit 31 First operational amplifier (amplifier)
32 Second operational amplifier (amplifier)
33 Third operational amplifier (amplifier)
34 Fourth operational amplifier (amplifier)
41 First switch circuit 42 Second switch circuit 51 Chopper clock generation circuit

Claims (9)

A first Hall element having a first terminal, a second terminal, a third terminal, and a fourth terminal;
A second Hall element having a first terminal, a second terminal, a third terminal, and a fourth terminal;
A current source for passing a drive current through a fourth terminal of the first Hall element and a fourth terminal of the second Hall element;
An inverting input terminal is connected to a first terminal of the first Hall element, a non-inverting input terminal is connected to a common voltage, and an output terminal is connected to a second terminal of the first Hall element. A first amplifier,
An inverting input terminal is connected to the third terminal of the second Hall element, a non-inverting input terminal is connected to a common voltage, and an output terminal is connected to the second terminal of the second Hall element. A Hall electromotive force signal detection circuit comprising: a second amplifier.   The current source is a first current source for flowing a drive current to the fourth terminal of the first Hall element, and a second current source for flowing a drive current to the fourth terminal of the second Hall element. The Hall electromotive force signal detection circuit according to claim 1, wherein the Hall electromotive force signal detection circuit is provided.   The Hall electromotive force signal detection circuit according to claim 1, wherein outputs are detected from a third terminal of the first Hall element and a first terminal of the second Hall element. A chopper clock generation circuit for generating a chopper clock signal;
A first switch circuit that switches connection of each terminal of the first Hall element in response to a chopper clock signal;
A second switch circuit that switches connection of each terminal of the second Hall element according to a chopper clock signal,
Each terminal of the first Hall element, the first amplifier, and the first current source are connected via the first switch circuit,
The terminals of the second Hall element, the second amplifier, and the second current source are connected to each other through the second switch circuit. 4. The Hall electromotive force signal detection circuit according to 3. Each terminal of the first Hall element is switched clockwise in order of the first terminal, the fourth terminal, the third terminal, and the second terminal,
The terminals of the second Hall element are switched in the order of the first terminal, the second terminal, the third terminal, and the fourth terminal in the counterclockwise direction. The Hall electromotive force signal detection circuit as described. Each terminal of the first Hall element is switched in the order of the first terminal, the second terminal, the fourth terminal, and the third terminal,
4. The hall according to claim 1, wherein each terminal of the second Hall element is switched in the order of a fourth terminal, a third terminal, a first terminal, and a second terminal. Electromotive force signal detection circuit. A magnetic converging plate in which the directions of magnetic fields input to the first Hall element and the second Hall element are opposite to each other;
Each terminal of the first Hall element is arranged clockwise with a first terminal, a second terminal, a third terminal, and a fourth terminal,
4. Each terminal of the second Hall element is arranged in a counterclockwise direction with a first terminal, a second terminal, a third terminal, and a fourth terminal. The Hall electromotive force signal detection circuit according to 1. A third Hall element having a first terminal, a second terminal, a third terminal, and a fourth terminal;
A fourth Hall element having a first terminal, a second terminal, a third terminal, and a fourth terminal;
A fourth terminal of the first Hall element; a fourth terminal of the second Hall element; a fourth terminal of the third Hall element; and a fourth terminal of the fourth Hall element. A current source for driving current to
An inverting input terminal is connected to a first terminal of the third Hall element, a non-inverting input terminal is connected to a third terminal of the first Hall element, and an output terminal is connected to the third Hall element. A third amplifier connected to the second terminal of the element;
An inverting input terminal is connected to the third terminal of the fourth Hall element, a non-inverting input terminal is connected to the third terminal of the second Hall element, and an output terminal is connected to the fourth Hall element. A fourth amplifier connected to the second terminal of the device;
2. The Hall electromotive force signal detection circuit according to claim 1, wherein outputs are detected from a third terminal of the third Hall element and a first terminal of the fourth Hall element.   The current source includes a first current source that causes a drive current to flow to a fourth terminal of the first Hall element, and a second current source that causes a drive current to flow to a fourth terminal of the second Hall element. A third current source for flowing a drive current to the fourth terminal of the third Hall element, and a fourth current source for flowing a drive current to the fourth terminal of the fourth Hall element. The Hall electromotive force signal detection circuit according to claim 8.

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