KR20160108169A - Magnetic sensor circuit - Google Patents

Abstract

The present invention provides a magnetic sensor circuit which does not output a voltage error on a spike to a signal processing circuit. The magnetic sensor circuit is configured to output an output signal to a signal processing circuit through a plurality of Hall devices driven by a first switch circuit and a second switch circuit controlled by a second control circuit. A first switch circuit controls timing, when a spike occurs on the output signal of each of the plurality of Hall devices, not to be identical; and the second switch circuit selectively outputs the output signal of the timing when the spike does not occur.

Description

[0001] MAGNETIC SENSOR CIRCUIT [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor circuit, and more particularly, to a magnetic sensor circuit capable of reducing a spike occurring at the time of terminal switching of a Hall element.

Although the magnetic sensor circuit includes a Hall element and a signal processing circuit, an offset voltage is generated in a Hall element or a signal processing circuit, and a non-zero voltage is output even in a zero magnetic field state in which no magnetic field is applied.

The cause of the offset voltage of the Hall element is manufacturing variation, stress, influence of the surrounding magnetic field, and the like. As to the problem of the offset voltage of the Hall element, a driving method called a spinning current method is generally used.

When a terminal is placed at four corners with a square Hall element, when a magnetic field is applied in the case where the driving current is supplied to the opposite terminal of 0 degree and the driving current is supplied to the opposite terminal of 90 degrees, (Reverse phase), and the voltages according to the magnetic field become the same phase. Therefore, these signals are added to obtain a significant signal in which the offset error is reduced, and signal processing is performed.

17 is a circuit diagram showing a conventional magnetic sensor circuit for spinning two times.

The Hall element 1 has four terminals (nodes N1 to N4) and is connected to the power supply voltage and the ground voltage through the first switch circuit 3 controlled by the first control circuit 5. [ The signal processing circuit 2 is connected to the Hall element 1 through the second switch circuit 4 controlled by the second control circuit 6. [

Fig. 18 shows a time chart of a conventional magnetic sensor circuit for spinning two times. In the figure, the control signal is switched on at the high level and the control signal is switched off at the low level. One spinning period is divided into two periods? 1 and? 2.

In the period? 1, the control signals SS1V, SS1G, SS1P, and SS1M become high level. Therefore, in the period? 1, the constant current source 15 is connected to the node N2, the ground voltage is connected to the node N4, and the node N1 is connected to the positive input terminal INP And the node N3 is connected to the negative input terminal INM.

In the period? 2, the control signals SS2V, SS2G, SS2P, and SS2M become high level. In the period? 2, the constant current source 7 is connected to the node N3, the ground voltage is connected to the node N1, the node N2 is connected to the positive input terminal INP, And the node N4 is connected to the node INM.

By the above connection, the differential signal INP-INM becomes the signal voltage Vsig corresponding to the magnetism in the period of? 1 and? 2. In the period? 1, the positive spike phase voltage is generated immediately after the switching, and the positive spike phase voltage is generated in the period? 2.

As a measure against the voltage error on the spike described above, for example, the methods of Patent Documents 1 and 2 are known. Patent Document 1 uses the fact that voltage errors on spikes occurring at the time of spinning switching in the clockwise direction and the counterclockwise direction occur at the inverse signs of the governor, and these are added or averaged to reduce errors. On the other hand, in Patent Document 2, a discrete signal processing circuit having a sample-and-hold circuit is premised on one Hall element. Immediately after spinning conversion, the Hall element and the signal processing circuit are separated, Since the signal processing is performed based on the held signal of the & hold circuit, the signal transmission in the error period of the spike phase immediately after the switching is masked, and the influence of the spike error on the signal processing accuracy is reduced.

U.S. Patent No. 6927572 U.S. Patent No. 5621319

In the method described in Patent Document 1, a method of canceling a positive spike phase error and a negative spike phase error is employed. However, the positive spike phase error and the negative spike phase error do not completely coincide with each other due to manufacturing variations, This is a residual error factor.

In the method of Patent Document 2, since there is a masked period in which the output signal of the Hall element is not transferred to the signal processing circuit on the premise of the discrete-time signal processing having the sample-and-hold circuit, It is not suitable for treatment.

It is an object of the present invention to provide a magnetic sensor circuit having a circuit for reducing a voltage error on a desired spike in both the continuous time signal processing circuit and the discrete time signal processing circuit .

The invention disclosed in the present invention is roughly constructed as follows for solving the problems.

A first switch circuit formed between a plurality of terminals of the plurality of Hall elements, a power supply terminal, and a ground terminal and having a plurality of Hall elements, A second switch circuit connected to a plurality of terminals of the plurality of hall elements for selectively outputting output signals of the plurality of hall elements, a first control circuit for outputting a first control signal to the first switch circuit, , A second control circuit for outputting a second control signal to the second switch circuit, and a signal processing circuit for receiving the output signal output from the second switch circuit and performing signal processing, wherein the first control circuit And controls the plurality of Hall elements so that the timing at which spikes occur in the output signals of the plurality of Hall elements is different, and the second control circuit controls the plurality of Hall elements The output signal of a predetermined period in which spikes are occurring is made non-selected and the output signal of the second switch circuit And the output of said second switch circuit selectively outputs one or more output signals of said plurality of Hall elements in all periods.

According to the present invention, the residual error occurring when the voltage error on the spike immediately after the spinning of the Hall element is directly canceled by the spike of the center does not occur. In addition, by selectively outputting a voltage value after a predetermined time after the voltage on the spike is lost by using a plurality of Hall elements, the spike phase voltage error caused by the Hall element capacitance can be greatly reduced. In addition, since the signal during the period in which the spike phase error is lost is always used, the spinning frequency can be increased.

Further, according to the present invention, each Hall element avoids a period of spike phase error, thereby making it possible to speed up the processing conversion rate of a signal processing circuit (for example, an analog-digital converter). It is also possible to continuously propagate the output signal voltage of the Hall element to the signal processing circuit, which is suitable for continuous signal processing. Further, when the signal processing circuit is used by multiplexing sampling to the first and second phases, the Hall output signal can be propagated without being interrupted. In addition, in the case of the discrete-time signal processing using the instrumentation amplifier, unnecessary charging / discharging does not occur, so that the consumption current of the instrumentation amplifier can be reduced.

1 is a circuit diagram of the magnetic sensor circuit of the first embodiment.
2 is a time chart showing the circuit operation of the magnetic sensor circuit of the first embodiment.
3 is a circuit diagram of the magnetic sensor circuit of the second embodiment.
4 is a circuit diagram showing an example of a first switch circuit of the magnetic sensor circuit of the second embodiment.
5 is a circuit diagram showing an example of a second switch circuit of the magnetic sensor circuit of the second embodiment.
6 is a time chart showing the circuit operation of the magnetic sensor circuit of the second embodiment.
7 is a circuit diagram of the magnetic sensor circuit of the third embodiment.
8 is a circuit diagram showing an example of a second switch circuit of the magnetic sensor circuit of the third embodiment.
9 is a time chart showing the circuit operation of the magnetic sensor circuit of the third embodiment.
10 is a circuit diagram of the magnetic sensor circuit of the fourth embodiment.
11 is a circuit diagram showing an example of a first switch circuit of the magnetic sensor circuit of the fourth embodiment.
12 is a circuit diagram showing an example of a second switch circuit of the magnetic sensor circuit of the fourth embodiment.
13 is a time chart showing the circuit operation of the magnetic sensor circuit of the fourth embodiment.
14 is a circuit diagram showing an example of the configuration of a Hall element of the magnetic sensor circuit of the present invention.
15 is a circuit diagram showing an example of the configuration of a Hall element of the magnetic sensor circuit of the present invention.
16 is a circuit diagram showing an example of the configuration of a drive circuit of the magnetic sensor circuit of the present invention.
17 is a circuit diagram showing a conventional magnetic sensor circuit for spinning two times.
18 is a time chart of a conventional magnetic sensor circuit for two spinning.

Embodiments of the magnetic sensor circuit of the present invention will be described below with reference to a circuit diagram.

≪ First Embodiment >

1 is a circuit diagram of the magnetic sensor circuit of the first embodiment.

The magnetic sensor circuit includes a first Hall element 1A, a second Hall element 1B, a first switch circuit 13, a second switch circuit 14, a first control circuit 11, A second control circuit 12, a constant current source 15, and a signal processing circuit 16. The signal processing circuit 16 corresponds to a chopping modulation / demodulation circuit, an adder, a filter processing circuit, an analog / digital converter, a comparator (magnetic switch circuit), and the like.

The first Hall element 1A has four terminals, and the nodes of the respective terminals are N1A to N4A. The second Hall element 1B has four terminals, and the nodes of the respective terminals are N1B to N4B. The signal processing circuit 16 has a normal phase input terminal INP and a negative phase input terminal INM.

The first Hall element 1A and the second Hall element 1B are connected to the power supply voltage and the ground voltage via the first switch circuit 13 controlled by the first control circuit 11, And is connected to the signal processing circuit 16 through the second switch circuit 14 controlled by the signal processing circuit 12.

The respective switches of the first switch circuit 13 are controlled by the control signals SS1VA, SS1VB, SS2VA, SS2VB, SS1GA, SS1GB, SS2GA, SS2GB. Each of the switches of the second switch circuit 14 is controlled by control signals SS1PA, SS1PB, SS2PA, SS2PB, SS1MA, SS1MB, SS2MA, SS2MB.

Next, the operation of the magnetic sensor circuit of the first embodiment will be described. 2 is a time chart showing the circuit operation of the magnetic sensor circuit of the first embodiment.

One spinning period is divided into a period (1) and a period (2). The period? 1 is divided into sub periods? 11 and? 12, and the period? 2 is divided into sub periods? 21 and? 22. The control signals SS1VA and SS1GA are at the high level in the period? 1 and the control signals SS2VA and SS2VG are at the high level in the period? 2 while the control signals SS1VB and SS1GB are at the high level in the periods? The control signals SS2VB and SS2GB become high level in the periods? 22 and? 11. The control signals SS1PA and SS1MA are at the high level in the period? 12 and the control signals SS2PA and SS2MA are at the high level in the period? 22 while the control signals SS1PB and SS1MB are at the high level in the period? The control signals SS2PB and SS2MB become high level in the period? 11.

Therefore, in the period? 11, the constant current source 15 is connected to the node N2A, the ground voltage is connected to the node N4A, the constant current source 15 is connected to the node N3B, N1B are connected to the ground voltage, and the two Hall elements are driven. The Hall element node N2B of the Hall element 1B is connected to the normal input terminal INP and the Hall element node N4B of the Hall element 1B is connected to the floating input terminal INM. In this period, since the spinning switching timing of the Hall element 1B is at the start of the period? 22, the voltage error on the spike does not occur in the differential output signal INP-INM. The operation principle of the period? 12, the period? 21 and the period? 22 is also the same as in the case of the differential signal in the period in which no voltage error on any one of the spike of the Hall element 1A and Hall element 1B occurs , And is selectively output to the input signal INP-INM of the signal processing circuit 16.

Therefore, in the case of the magnetic sensor circuit of the first embodiment, there is an advantage that an error in the spike is not generated at the input of the signal processing circuit 16. [ In addition, in the present embodiment, since the period of the spike phase error is masked and the voltage in the stable period is selected, the spinning frequency and the signal processing conversion rate of the signal processing circuit 16 (for example, Can be increased. Therefore, the S / N of the magnetic sensor circuit can be kept constant.

Further, the output signal voltage of the Hall element can be continuously propagated to the signal processing circuit 16, which is preferable for continuous signal processing.

Further, in the case of the discrete-time signal processing using the instrumentation amplifier, unnecessary charging / discharging does not occur and the consumption current of the instrumentation amplifier is not increased.

≪ Second Embodiment >

3 is a circuit diagram of the magnetic sensor circuit of the second embodiment.

The magnetic sensor circuit of the present embodiment has a first Hall element 1A, a second Hall element 1B, a third Hall element 1C, a fourth Hall element 1D, a first switch circuit 33, a second switch circuit 34, a first control circuit 31, a second control circuit 32, and a signal processing circuit 36.

The third Hall element 1C and the fourth Hall element 1D have four terminals in the same manner as the first Hall element 1A and the second Hall element 1B and the nodes of the respective terminals are N1C to N4C And N1D to N4D. The signal processing circuit 36 has normal input terminals INPA, INPB, INPC, INPD and floating input terminals INMA, INMB, INMC, INMD.

The Hall element is formed by adding the third Hall element 1C and the fourth Hall element 1D from the magnetic sensor circuit of the first embodiment and adding the same between the first switch circuit 33 and the second switch circuit 34 Respectively.

A switch is added to the first switch circuit 33 in accordance with the same four Hall elements. 4 is a circuit diagram showing an example of the first switch circuit 33. As shown in Fig. Each input terminal, each output terminal, and each switch are connected and controlled in the relationship as shown.

The second switch circuit 34 has eight output terminals corresponding to the respective input terminals of the signal processing circuit 36. 5 is a circuit diagram showing an example of the second switch circuit 34. As shown in Fig. Each input terminal, each output terminal, and each switch are connected and controlled in the relationship as shown.

Four signals are input to each of the normal input terminals INPA, INPB, INPC and INPD and the floating input terminals INMA, INMB, INMC and INMD, To a voltage level or a current level, and performs addition signal processing.

Next, the operation of the magnetic sensor circuit of the second embodiment will be described. 6 is a time chart showing the circuit operation of the magnetic sensor circuit of the second embodiment.

One spinning period is divided into a period? 1 and a period? 2, a period? 3 and a period? 4. The period? 1 is divided into sub periods (? 11 and? 12 and? 13 and? 14), the period? 2 is divided into sub periods (? 21 and? 22 and? 23 and? 24) 32 and? 33 and? 34), and the period? 4 is divided into sub periods (? 41 and? 42 and? 43 and? 44). The control signals SS1VA and SS1GA are at the high level in the period? 1 and the control signals SS2VA and SS2VG are at the high level in the period? 2 while the control signals SS3VA and SS3VG are at the high level in the period? (SS4VA, SS4VG) become high level in the period? 4, and these become control signals for driving the Hall element 1A. Similarly, the driving signals of the other Hall elements 1B, 1C, and 1D have four phases. However, as shown in Fig. 6, the phases of the clocks are shifted by one sub period.

The control signals SS1PA and SS1MA are at the high level in the periods phi 12 to phi 14 and the control signals SS2PA and SS2MA are at the high level in the periods phi 22 to phi 24 with respect to the control signal regarding the output signal of the Hall element 1A. The control signals SS3PA and SS3MA are at the high level in the periods? 32 to? 34 and the control signals SS4PA and SS4MA are at the high level during the period? 42 to? 44, respectively. As shown in Fig. 6, the other Hall elements 1B, 1C and 1D also have control signals having the same phase relationship, but the phases of the clocks are shifted by one Hall element for each sub period.

Therefore, although spike occurs in the Hall element 1A in the sub period? 11, three signals of the Hall elements 1B, 1C, and 1D are input to the signal processing circuit 36. [ In the other sub periods as well, the output signals of the three Hall elements that do not generate spikes are transferred to the signal processing circuit 36 and added.

Therefore, in the case of the magnetic sensor circuit of the present embodiment, there is an advantage that an error in the spike is not generated at the input of the signal processing circuit 36. [ Further, the output signal voltage of the Hall element can be continuously propagated to the signal processing circuit 36, which is preferable for continuous signal processing.

≪ Third Embodiment >

7 is a circuit diagram of the magnetic sensor circuit of the third embodiment.

The magnetic sensor circuit of the present embodiment has a first Hall element 1A, a second Hall element 1B, a third Hall element 1C, a fourth Hall element 1D, a first switch circuit 33, a second switch circuit 74, a first control circuit 31, a second control circuit 72, and a signal processing circuit 16.

The second embodiment differs from the second embodiment in that the configuration of the second switch circuit 74 is different from the control signal of the second control circuit 72 and the point that the signal processing circuit 16 is connected to the normal input terminal INP and the floating input And a pair of terminals INM.

Fig. 8 is a circuit diagram showing an example of the second switch circuit 74. Fig. Each input terminal, each output terminal, and each switch are connected and controlled in the relationship as shown.

Next, the operation of the magnetic sensor circuit of the third embodiment will be described. 9 is a time chart showing the circuit operation of the magnetic sensor circuit of the third embodiment.

The time chart of the present embodiment differs from the time chart of the second embodiment in that the control signal of the second switch circuit 72 is different. The control signals SS1PA and SS1MA are high level and the control signals SS2PA and SS2MA are high level during the period? 24 and the period? 34 for the first hall element 1A, The control signals SS4PA and SS4MA are at the high level and the control signals SS4PA and SS4MA are at the high level during the period? The control signals for the second Hall element 1B to the fourth Hall element 1D are also in the same phase relationship, but the phases of the clocks are shifted by one sub-period between the Hall elements. Therefore, the signal processing input INP-INM is a signal for inputting the signal of the second Hall element 1B in the period? 11, the signal of the third Hall element 1C in the period? 12, the signal of the fourth Hall element 1D The signal of the first Hall element 1A is selected in the period of? 14. The input signal to the signal processing circuit 16 is determined on the same principle in other sub periods as well.

Therefore, the magnetic sensor circuit of the present embodiment has an advantage that an error in the spike is not generated at the input of the signal processing circuit 16. In addition, since four Hall elements are used in this embodiment, the period of the spike phase error is masked and a stable period can be divided into three sub periods. Therefore, the voltage error on the spike due to the Hall element capacitance becomes an exponential function It becomes infinitely small. Therefore, it is possible to further improve the spinning frequency and the signal processing conversion rate (for example, the sampling rate of the analog-to-digital converter) of the signal processing circuit 16. Therefore, since the S / N ratio can be kept constant as a system of the magnetic sensor circuit, the loss can be avoided by increasing the clock rate. Further, the output signal voltage of the Hall element can be continuously propagated to the signal processing circuit 16, which is preferable for continuous signal processing.

≪ Fourth Embodiment &

10 is a circuit diagram of the magnetic sensor circuit of the fourth embodiment.

The magnetic sensor circuit of this embodiment is the same as the circuit configuration of the second embodiment, but the circuits of the first switch circuit 103 and the second switch circuit 104 are different.

11 is a circuit diagram showing an example of the first switch circuit 103. As shown in Fig. Each input terminal, each output terminal, and each switch are connected and controlled in the relationship as shown. Thus, the Hall element 1A is spun clockwise, the Hall element 1B is spun in a counterclockwise direction, the Hall element 1C is spun in a clockwise direction, and the Hall element 1D is spun in a counterclockwise direction. So that the connection is made.

12 is a circuit diagram showing an example of the second switch circuit 104. As shown in Fig. Each input terminal, each output terminal, and each switch are connected and controlled in the relationship as shown. The second switch circuit 104 also has a connection corresponding to the same spinning as that of the first switch circuit 103.

Next, the operation of the magnetic sensor circuit of the fourth embodiment will be described. 13 is a time chart showing the circuit operation of the magnetic sensor circuit of the fourth embodiment.

The time chart of this embodiment is the same as the time chart of the second embodiment except that the control signal is the same and the sign of the voltage error on the spike of the differential signal between the Hall element 1B and Hall element 1D is negative have. This is because the method of spinning of the Hall element is different.

In the magnetic sensor circuit of the present embodiment, a period in which there is no spike is selected as the output. However, in an actual circuit, the time constant τ is expressed as A × exp (-T / τ) And the masked correction time). Therefore, a minute error (-T /?) Actually occurs for the Hall elements 1A and 1C and a small error (-1) for the Hall elements 1B and 1D. × A × exp (-T / τ)) actually occurs. Therefore, by canceling the influence of the residual error of the signal correction, the error component of the signal can be made smaller.

Since the magnetic sensor circuit of the present embodiment selectively outputs the corrected voltage after the disappearance of the spike, the influence due to the waveform shape difference between the positive and negative spike voltages can hardly be felt.

Fig. 14 and Fig. 15 are circuit diagrams showing an example of the configuration of a Hall element of the magnetic sensor circuit of the present invention.

14, two Hall elements 1a and 1b are connected to terminals N1 to N4 so as to be one Hall element 1 as shown in the drawing. The Hall elements 1a and 1b are connected so that each of the terminals differs by 0 degree and 90 degrees so as to be a Hall element 1. By configuring the Hall element 1 in this way, it is possible to suppress the influence of manufacturing variations and stresses caused by the layout.

The configuration of the Hall element 1 in Fig. 15 is also the same.

16 is a circuit diagram showing an example of the configuration of a drive circuit for a Hall element of the magnetic sensor circuit of the present invention.

The driving circuit of Fig. 16 forms four constant current sources 15A, 15B, 15C and 15D for driving the four Hall elements 1A, 1B, 1C and 1D. Then, the first switch circuit 163 performs control so as to switch the constant current source for driving the Hall element for each spinning. By configuring the drive circuit in this manner, it is possible to further suppress the slight signal fluctuation occurring in the drive stage at the time of spinning switching.

In the case of the magnetic sensor circuit having four Hall elements as shown in Fig. 16, the constant current source for driving the Hall element is switched by four cycles of four spins. By performing such spinning control, the influence of the deviation of the current values of the constant current sources 15A, 15B, 15C and 15D can be suppressed.

According to the drive circuit of Fig. 16, the magnetic sensor circuit of the present invention can suppress a slight signal fluctuation occurring in the drive stage at the time of spinning switching. Further, according to the above-described driving method, the current deviation of each constant current source can be suppressed.

In the above description of the embodiment of the present invention, the shape of the Hall element, the terminal and the positional relationship (0 degrees, 90 degrees, 180 degrees, 270 degrees) and the like are not limited to those shown in the drawings, Are also included in the scope of the present invention.

It is needless to say that the present invention is not limited to the above-described embodiments but includes various modifications and modifications that can be attained by those skilled in the art within the scope of the present invention.

1A, 1B, 1C, 1D: Hall element
11, 31: a first control circuit
12, 32: a second control circuit
13, 33, 103: first switch circuit
14, 34, 104: second switch circuit
15, 15A, 15B, 15C, 15D: constant current source
16, 36: signal processing circuit

Claims (4)

A plurality of Hall elements having a plurality of terminals,
A first switch circuit formed between a plurality of terminals of the plurality of Hall elements, a power supply terminal and a ground terminal, for switching and supplying a driving current to the plurality of Hall elements;
A second switch circuit connected to a plurality of terminals of the plurality of Hall elements and selectively outputting output signals of the plurality of Hall elements;
A first control circuit for outputting a first control signal to the first switch circuit;
A second control circuit for outputting a second control signal to the second switch circuit,
And a signal processing circuit for receiving an output signal output from the second switch circuit and performing signal processing,
The first control circuit controls the plurality of Hall elements so that the timing at which spikes occur in output signals of the plurality of Hall elements is different,
The second control circuit selects an output signal of a predetermined period in which spikes are occurring among the output signals of the plurality of hall elements as a non-selection signal, and selects, as output signals of the plurality of Hall elements, Controls the second switch circuit to select an output signal of a predetermined period,
And the output of said second switch circuit is selected and output by any one or more output signals of said plurality of Hall elements in all periods. The method according to claim 1,
And a constant current source is formed between the first switch circuit and the power supply terminal. 3. The method of claim 2,
The constant current source is formed corresponding to the plurality of Hall elements,
And said first switch circuit is connected to said plurality of Hall elements by switching every spinning. 4. The method according to any one of claims 1 to 3,
Wherein the Hall element comprises:
And the plurality of Hall elements are connected to the terminals of the Hall elements so as to be one Hall element.

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