A fully integrated closed-loop Hall sensor device

Abstract

The present invention discloses a fully integrated closed-loop Hall sensor device, which includes: a first signal detection module, a second signal detection module, a signal superposition module, and a signal feedback module; the first signal detection module and the second signal detection module respectively obtain the magnetic signal variation at a preset position and convert it into a first voltage signal and a second voltage signal; the signal superposition module receives the first voltage signal and the second voltage signal, and calculates the voltage difference between the first voltage signal and the second voltage signal; the signal feedback module receives the voltage difference and obtains a feedback current value according to the voltage difference, and performs feedback compensation on the first signal detection module and the second signal detection module through the feedback current. The effective magnetic field of the closed-loop feedback coil is amplified by the Hall sensor branches with different gains, so as to solve the problem that the entire closed-loop Hall sensor cannot be integrated into a single chip due to the limitation of current and effective magnetic field strength.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a fully integrated closed-loop Hall sensor device. Background Art

[0002] A Hall sensor is a device that converts changes in a magnetic field into changes in an output voltage. The most basic application of a Hall sensor is to measure the strength of a magnetic field. In addition, it can also be used to measure physical quantities that generate and affect a magnetic field, such as proximity switches, position measurement, speed measurement, and current measurement. Due to the large dynamic range, good linearity, and ease of integration of Hall sensors, they are widely used in automotive, industrial, and daily consumer products. Hall sensors can be divided into two categories based on their working principles: open-loop Hall and closed-loop Hall. Open-loop Hall sensors (see Figure 1 ) consists of a Hall element and a linear amplifier. Its output voltage is proportional to the magnetic field strength passing through the Hall element. Its output voltage rises or falls according to the magnetic field characteristics and strength: As the magnetic field strength increases, the output voltage of the sensor also increases, so the corresponding magnetic field strength can be inferred by measuring the output voltage:

[0003] B=V out / G BtoV ,

[0004] Where B is the measured magnetic field strength, V out is the output voltage of the Hall sensor, G BtoV is the magnetic field to voltage conversion coefficient (including the linear amplifier gain).

[0005] Closed-loop Hall sensor (see Figure 2 ) is also called a compensated sensor, that is, the magnetic field detected by the Hall element is compensated by the magnetic field generated by a secondary coil current, so that the Hall device is in a working state of detecting zero magnetic flux. Therefore, the closed-loop Hall sensor can achieve high linearity and temperature stability, which is very attractive for high-precision and high-stability applications.

[0006] Existing closed-loop Hall sensors are mainly implemented at the system level. Figure 2 As shown in the figure, the closed-loop Hall is mainly composed of an open-loop Hall sensor, an integrator, and a feedback coil. When a magnetic field passes through the Hall device, the generated voltage output is converted into a current through the integrator to drive the feedback coil to generate an opposite magnetic field, thereby achieving compensation and making the output of the Hall element zero. In this way, the magnitude of the measured magnetic field can be inferred by measuring the current intensity of the feedback coil.

[0007] because Figure 2The magnetic field strength generated by the coil in the system is limited, and usually the coil requires a very large current to achieve the compensation effect. To solve this problem, the traditional closed-loop Hall sensor introduces a magnetic core ( Figure 3 ) to achieve the effect of magnetic field amplification, thereby reducing the current required in the coil.

[0008] The existing closed-loop Hall technology has the following problems: First, the measurement range of the integrated closed-loop Hall based on the existing technology is extremely low: since the standard integrated circuit process cannot integrate the magnetic core, the feedback magnetic field is completely realized by the feedback coil inside the chip. Due to the current limitation in the chip, the magnetic field measurement range of the integrated closed-loop Hall sensor chip is less than 10mT (milli-Tesla, 10 -3 ). In reality, most applications require measuring magnetic fields of tens or even hundreds of mT. Therefore, there are currently no fully integrated closed-loop Hall sensors on the market. Second, system-level closed-loop Hall has problems such as cost, volume, and production cycle: Due to the above reasons, all current closed-loop Hall sensors are implemented by adding magnetic cores and coils to the open-loop Hall chip ( Figure 3 ). This is costly, the large size is not conducive to integration, and the mass production period is long. Third, the traditional closed-loop Hall sensor has great uncertainty in the performance requirements of the open-loop Hall sensor chip in the loop: Since the traditional closed-loop Hall sensor product design is independent of the Hall sensor chip design in the loop, the uncertainty of chip performance has a serious impact on the entire closed-loop Hall sensor system, including yield, consistency, etc. Fourth, the traditional closed-loop Hall sensor uses a magnetic core, which has defects such as linearity and hysteresis: the traditional closed-loop Hall sensor uses a magnetic core to enhance the signal strength, but the magnetic core will cause the system linearity to decrease when it is close to saturation; at the same time, the use of the magnetic core will introduce a hysteresis effect, resulting in an increase in system errors, and a demagnetization circuit is required to solve the response problem. Summary of the invention

[0009] The purpose of the embodiment of the present invention is to provide a fully integrated closed-loop Hall sensor device, which forms an amplification effect on the effective magnetic field of the closed-loop feedback coil through two Hall sensor branches with different gains, thereby solving the problem that the entire closed-loop Hall sensor cannot be integrated into a single chip due to the limitations of current and effective magnetic field strength.

[0010] To solve the above technical problems, an embodiment of the present invention provides a fully integrated closed-loop Hall sensor device, including: a first signal detection module, a second signal detection module, a signal superposition module, and a signal feedback module;

[0011] The first signal detection module and the second signal detection module respectively obtain the magnetic signal variation at the preset position and convert it into a first voltage signal and a second voltage signal;

[0012] The signal superposition module receives the first voltage signal and the second voltage signal, and calculates a voltage difference between the first voltage signal and the second voltage signal;

[0013] The signal feedback module receives the voltage difference and obtains a feedback current value according to the voltage difference, and performs feedback compensation on the first signal detection module and the second signal detection module through the feedback current.

[0014] Further, the first signal detection module includes: a first coil and a first Hall sensor unit, and the second signal detection module includes: a second coil and a second Hall sensor unit;

[0015] The first coil and the second coil are connected in series and then connected to the signal feedback module;

[0016] The first Hall sensor unit is arranged at a position corresponding to the first coil, and the second Hall sensor is arranged at a position corresponding to the second coil;

[0017] The difference in amplification factor between the first Hall sensor unit and the second Hall sensor unit is a preset value.

[0018] Furthermore, the first coil and the second coil have the same size and opposite polarities.

[0019] Further, the first Hall sensor unit includes: a first Hall element and a first amplifier connected in series, the first Hall element is arranged at a corresponding position of the first coil, and an output end of the first amplifier is connected to the signal superposition module;

[0020] The second Hall sensor unit comprises: a second Hall element and a second amplifier connected in series, the second Hall element is arranged at a corresponding position of the second coil, and the output end of the second amplifier is connected to the signal superposition module;

[0021] The first Hall element is the same as the second Hall element, and the difference in amplification factor between the first amplifier and the second amplifier is the preset value.

[0022] Furthermore, the voltage difference output by the signal superposition module is:

[0023]

[0024] Wherein, B is the magnetic field strength of the magnetic field to be tested, R is the resistance value in the feedback loop, G1 is the amplification factor of the first Hall sensor unit, G2 is the amplification factor of the second Hall sensor unit, S 12B is the conversion factor from current to magnetic field.

[0025] Further, the first voltage signal value output by the first Hall sensor unit is:

[0026]

[0027] The second voltage signal value output by the second Hall sensor unit is:

[0028]

[0029] Further, the signal feedback module includes: an integrator and a feedback resistor;

[0030] The integrator input end is connected to the signal superposition module, and the output end is connected to the first signal detection module and the second signal detection module;

[0031] The feedback resistor is arranged in a feedback loop.

[0032] Furthermore, the resistance of the feedback resistor is adjustable, and the feedback current value can be changed by adjusting the resistance of the feedback resistor.

[0033] Furthermore, the temperature coefficient of the feedback resistor is smaller than a preset temperature coefficient.

[0034] Furthermore, the fully integrated closed-loop Hall sensor device further comprises: a signal driving module;

[0035] The signal driving module is arranged in series between the signal superposition module and the signal feedback module.

[0036] The above technical solution of the embodiment of the present invention has the following beneficial technical effects:

[0037] Through two Hall sensor branches with different gains, an effective magnetic field amplification effect is formed for the closed-loop feedback coil, which solves the problem that the entire closed-loop Hall sensor cannot be integrated into a single chip due to the limitations of current and effective magnetic field strength; in addition, the advantages of the closed-loop system are fully utilized, so that the entire system is not affected by the external environment, such as chip process angle, power supply voltage fluctuation, and temperature changes, making the entire system more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic diagram of an open-loop Hall sensor provided by an embodiment of the present invention;

[0039] Figure 2 is a schematic diagram of a traditional closed-loop Hall sensor provided by an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of a traditional closed-loop Hall sensor with a magnetic core provided in an embodiment of the present invention;

[0041] Figure 4 The fully integrated closed-loop Hall sensor device provided by the embodiment of the present invention is Figure 1 ;

[0042] Figure 5 The fully integrated closed-loop Hall sensor device provided by the embodiment of the present invention is Figure 2 . DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0044] Please refer to Figure 4 An embodiment of the present invention provides a fully integrated closed-loop Hall sensor device, including: a first signal detection module, a second signal detection module, a signal superposition module, and a signal feedback module; the first signal detection module and the second signal detection module respectively obtain the magnetic signal change at a preset position and convert it into a first voltage signal and a second voltage signal; the signal superposition module receives the first voltage signal and the second voltage signal, and calculates the voltage difference between the first voltage signal and the second voltage signal; the signal feedback module receives the voltage difference and obtains a feedback current value based on the voltage difference, and performs feedback compensation on the first signal detection module and the second signal detection module through the feedback current.

[0045] The system-level closed loop requires additional magnetic cores and coils, which leads to high costs and large size that are not conducive to integration. In addition, the mass production cycle is relatively long. However, if a closed-loop Hall is made inside the chip under the existing technology, it will be limited by the measurement range. If a closed-loop Hall is made inside the chip under the existing technology, it will be limited by the measurement range. Since there is no need to carry a magnetic core, the closed-loop Hall sensor device using the technology of the present invention solves the defects of linearity and hysteresis of the system-level closed-loop Hall at the same time.

[0046] The embodiment of the present invention solves the problem that the closed-loop Hall sensor cannot be integrated due to chip limitations through circuit technology improvements, improves the performance of the closed-loop Hall sensor in the chip to the level of the system-level closed-loop Hall, and achieves the purpose of compensating for a larger measured magnetic field with a smaller feedback current inside the chip. This solves the major problem that restricts the integration of Hall sensors in the chip.

[0047] In a specific embodiment of the present invention, the first signal detection module includes: a first coil and a first Hall sensor unit, and the second signal detection module includes: a second coil and a second Hall sensor unit; the first coil and the second coil are connected in series and connected to the signal feedback module; the first Hall sensor unit is arranged at a corresponding position of the first coil, and the second Hall sensor is arranged at a corresponding position of the second coil; the difference in amplification factor between the first Hall sensor unit and the second Hall sensor unit is a preset value.

[0048] Specifically, the first coil and the second coil have the same size and opposite polarities.

[0049] Furthermore, the first Hall sensor unit includes: a first Hall element and a first amplifier connected in series, the first Hall element is arranged at a corresponding position of the first coil, and the output end of the first amplifier is connected to the signal superposition module; the second Hall sensor unit includes: a second Hall element and a second amplifier connected in series, the second Hall element is arranged at a corresponding position of the second coil, and the output end of the second amplifier is connected to the signal superposition module; wherein, the first Hall element is the same as the second Hall element, and the difference in amplification factor between the first amplifier and the second amplifier is a preset value.

[0050] The voltage difference at the output of the signal superposition module is:

[0051]

[0052] Wherein, B is the magnetic field strength of the magnetic field to be tested, R is the resistance value in the feedback loop, G1 is the amplification factor of the first Hall sensor unit, G2 is the amplification factor of the second Hall sensor unit, S 12B is the conversion factor from current to magnetic field.

[0053] Furthermore, the magnetic field strength of the magnetic field to be tested is:

[0054]

[0055] Among them, B comp is the compensation magnetic field strength value formed by the first coil and the second coil.

[0056] Specifically, the signal feedback module includes: an integrator and a feedback resistor; the integrator input end is connected to the signal superposition module, and its output end is connected to the first signal detection module and the second signal detection module; the feedback resistor is set in the feedback loop.

[0057] The subtractor subtracts the output signals of the two Hall sensor units, and the integrator converts the output of the subtractor into a current to drive the feedback coil to generate a compensation magnetic field.

[0058] Furthermore, the resistance of the feedback resistor is adjustable, and the feedback current value can be changed by adjusting the resistance of the feedback resistor. By setting the feedback resistor as an adjustable resistor, it is used to adjust and read the feedback compensation current, so as to adjust the measurement sensitivity and dynamic range, so that the entire system can be integrated into the chip.

[0059] Furthermore, the temperature coefficient of the feedback resistor is less than the preset temperature coefficient. The temperature coefficient of the entire fully integrated Hall sensor device is mainly determined by the temperature coefficient of the feedback resistor. In practical applications, resistors with very low temperature coefficients can be found, thereby ensuring that the temperature coefficient of the entire test system is very low.

[0060] In addition, the fully integrated closed-loop Hall sensor device further includes: a signal driving module; the signal driving module is arranged in series between the signal superposition module and the signal feedback module.

[0061] The working principle of the fully integrated Hall sensor device is described below:

[0062] When the chip is exposed to a magnetic field, the first Hall element and the second Hall element will convert the magnetic field into voltage and output it to the corresponding first amplifier and second amplifier.

[0063] First, ignoring the influence of the feedback coil, the outputs of the two branches are:

[0064] V o1 =B·G1 (1)

[0065] V o2 =B·G2 (2)

[0066] Where: G1 and G2 are the magnifications of the two branches respectively. This magnification includes the conversion rate of the Hall element and the gain of the amplifier. B is the magnetic field strength of the magnetic field to be tested.

[0067] Since the amplification factors of the two branches are different, a non-zero voltage will be generated at the output of the subtractor. This voltage will be superimposed on the feedback resistor R after passing through the integrator to generate a feedback current. This feedback current will drive the first coil and the second coil to generate a corresponding compensation magnetic field. Since the coils of the two branches are in opposite directions, the compensation magnetic fields generated are also opposite. Therefore, the following will be obtained at the output ends of the two branches:

[0068]

[0069]

[0070] Where S I2Bis the conversion coefficient from current to magnetic field (this coefficient is related to the physical size of the coil and the size of the Hall element). At the same time, since the entire system is a negative feedback loop, under ideal conditions, the negative feedback will make the outputs of the two branches tend to be equal, making the input of the integrator zero. When the negative feedback loop is stable, it can be deduced that:

[0071]

[0072] Therefore, the output voltage Vout of the integrator in the stable state of the loop is:

[0073]

[0074] Therefore, the driving current in the feedback coil can be deduced as:

[0075]

[0076] Under this driving current, we can calculate the compensation magnetic field strength formed by the feedback coil as:

[0077]

[0078] Then the strength of the measured magnetic field is:

[0079]

[0080] From the above formula, we can see that due to The existence of the coefficient allows this system to test a larger external magnetic field with only a smaller coil drive current. For example: if the amplifier gain is designed so that If the value is 0.1, the on-chip coil generates a 10mT magnetic field, which allows the entire system to test an external magnetic field of 100mT. The fully integrated closed-loop Hall sensor can be used to test a larger magnetic field range. By adjusting the value of the resistor R, the current intensity of the feedback coil can be adjusted to ensure that the current in the chip is maintained within a reasonable range. This effectively solves the problem of being unable to integrate a closed-loop Hall sensor due to the limitation of the magnetic field intensity that can be generated in the chip, making a fully integrated closed-loop Hall sensor possible.

[0081] In addition to the above advantages, since the entire system of this invention can be integrated into a single chip, the circuit design and layout matching can ensure The coefficient maintains a very high stability under different conditions (process, voltage, temperature), so that the performance of the entire test system is not affected by PVT (process angle, voltage, temperature). From formula (9), we can see that the temperature coefficient of the entire system is mainly determined by the temperature characteristics of the resistor R. In practical applications, we can find resistors with very low temperature coefficients, thereby ensuring that the temperature coefficient of the entire test system is very low.

[0082] Please refer to Figure 5 , the subtraction function after the two voltage amplifiers G1 and G2 is realized by an integrator. After the integrator, an additional output stage operational amplifier provides sufficient driving capability for the feedback coil. The driving resistor R0 is located in the feedback loop of the system. From this circuit, the transfer function of the complete output voltage can be further derived as follows:

[0083]

[0084] When the frequency of the magnetic field to be measured is direct current (DC), simplifying the formula can obtain the same result as formula (5).

[0085] The bandwidth of this circuit can be derived from formula (10):

[0086]

[0087] It can be seen from formula (6) and formula (11) that this invention not only realizes the closed-loop Hall system in the chip, but also successfully disconnects the DC gain (mainly determined by the ratio of G1 and G2) and bandwidth of the system, so that these two parameters can be designed relatively independently.

[0088] The above process forms an amplification effect on the effective magnetic field of the closed-loop feedback coil through two Hall sensor branches with different gains. For details, see the derivation process of formula (1)-formula (9), which solves the problem that the entire closed-loop Hall sensor cannot be integrated into a single chip due to the limitation of current and effective magnetic field strength. In addition to the advantages of integration, the present invention also gives full play to the advantages of the closed-loop system, so that the entire system is not affected by the external environment, such as chip process angle, power supply voltage fluctuation, and temperature change, making the entire system more stable.

[0089] The embodiment of the present invention aims to protect a fully integrated closed-loop Hall sensor device, including: a first signal detection module, a second signal detection module, a signal superposition module, and a signal feedback module; the first signal detection module and the second signal detection module respectively obtain the magnetic signal change at a preset position and convert it into a first voltage signal and a second voltage signal; the signal superposition module receives the first voltage signal and the second voltage signal, and calculates the voltage difference between the first voltage signal and the second voltage signal; the signal feedback module receives the voltage difference and obtains a feedback current value based on the voltage difference, and performs feedback compensation on the first signal detection module and the second signal detection module through the feedback current. The above technical solution has the following effects:

[0090] Through two Hall sensor branches with different gains, an effective magnetic field amplification effect is formed for the closed-loop feedback coil, which solves the problem that the entire closed-loop Hall sensor cannot be integrated into a single chip due to the limitations of current and effective magnetic field strength; in addition, the advantages of the closed-loop system are fully utilized, so that the entire system is not affected by the external environment, such as chip process angle, power supply voltage fluctuation, and temperature changes, making the entire system more stable.

[0091] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A fully integrated closed-loop Hall sensor device, characterized in that: include: A first signal detection module, a second signal detection module, a signal superposition module, and a signal feedback module; The first signal detection module and the second signal detection module respectively obtain the magnetic signal variation at the preset position and convert it into a first voltage signal and a second voltage signal; The signal superposition module receives the first voltage signal and the second voltage signal, and calculates a voltage difference between the first voltage signal and the second voltage signal; The signal feedback module receives the voltage difference and obtains a feedback current value according to the voltage difference, and performs feedback compensation on the first signal detection module and the second signal detection module through the feedback current; The first signal detection module includes: a first coil and a first Hall sensor unit, and the second signal detection module includes: a second coil and a second Hall sensor unit; The first coil and the second coil are connected in series and then connected to the signal feedback module; The first Hall sensor unit is arranged at a position corresponding to the first coil, and the second Hall sensor is arranged at a position corresponding to the second coil; The difference in amplification factor between the first Hall sensor unit and the second Hall sensor unit is a preset value.

2. The fully integrated closed-loop Hall sensor device according to claim 1, characterized in that: The first coil and the second coil have the same size and opposite polarities.

3. The fully integrated closed-loop Hall sensor device according to claim 1, characterized in that: The first Hall sensor unit comprises: a first Hall element and a first amplifier connected in series, the first Hall element is arranged at a corresponding position of the first coil, and an output end of the first amplifier is connected to the signal superposition module; The second Hall sensor unit comprises: a second Hall element and a second amplifier connected in series, the second Hall element is arranged at a corresponding position of the second coil, and the output end of the second amplifier is connected to the signal superposition module; The first Hall element is the same as the second Hall element, and the difference in amplification factor between the first amplifier and the second amplifier is the preset value.

4. The fully integrated closed-loop Hall sensor device according to claim 1, characterized in that: The voltage difference output by the signal superposition module is: , Where B is the magnetic field strength of the magnetic field to be tested, R is the resistance value in the feedback loop, is the amplification factor of the first Hall sensor unit, is the amplification factor of the second Hall sensor unit, is the conversion factor from current to magnetic field.

5. The fully integrated closed-loop Hall sensor device according to claim 4, characterized in that: The first voltage signal value output by the first Hall sensor unit is: ， The second voltage signal value output by the second Hall sensor unit is: ； Where B is the magnetic field strength of the magnetic field to be tested, R is the resistance value in the feedback loop, is the amplification factor of the first Hall sensor unit, is the amplification factor of the second Hall sensor unit, is the conversion factor from current to magnetic field.

6. The fully integrated closed-loop Hall sensor device according to claim 1, characterized in that: The signal feedback module includes: an integrator and a feedback resistor; The integrator input end is connected to the signal superposition module, and the output end is connected to the first signal detection module and the second signal detection module; The feedback resistor is arranged in a feedback loop.

7. The fully integrated closed-loop Hall sensor device according to claim 6, characterized in that: The resistance value of the feedback resistor is adjustable, and the feedback current value can be changed by adjusting the resistance value of the feedback resistor.

8. The fully integrated closed-loop Hall sensor device according to claim 6, characterized in that: The temperature coefficient of the feedback resistor is less than a preset temperature coefficient.

9. The fully integrated closed-loop Hall sensor device according to any one of claims 1 to 8, characterized in that: Also includes: Signal driver module; The signal driving module is arranged in series between the signal superposition module and the signal feedback module.

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