BG65231B1 - Magnetosensitive sensor - Google Patents

Abstract

The magnetosensitive sensor has parallel axis of magnetic sensitivity, functioning on the basis of the principle of Hall. By it, electric control (including setting to zero) of the inevitable offset by changing the current values across the first and the second current source is possible. It has two equivalent outputs, reduced temperature drift of the outputs and improved measuring precision. The two separate outputs allow taking out the inverted output signals, which results in doubling the initial voltage and to serious reduction of the offset value and its temperature drift. The sensor comprises a semiconductor substrate (1), on one of its sides of which four ohmic contacts of rectangular shape are formed, positioned parallel to their long sides. The contacts are suitably connected with two independent current sources (6, 7), which operate in current generation mode. Outputs of the magnetic sensitive sensor are the second (3) and the third (4), and the first (2) and fourth (5) ohmic contacts, and the external magnetic field (10) is applied perpendicularly to the cross section of the substrate (1).

Description

Technical field

The invention relates to a magnetic-sensitive sensor, applicable in the control-measuring technique, magnetometry, control systems, microsystems, sensors, contactless automation, positioning of objects in space, landscaping, military affairs and the energy field.

BACKGROUND OF THE INVENTION

A magnetically sensitive sensor is known, comprising a semiconductor substrate of impurity type, on one side of which four rectangular ohmic contacts, first, second, third and fourth, parallel to their long sides, are formed on one side at a distance. The first and third ohmic contacts are power and connected to the terminals of the power source, and the second and fourth ohmic contacts are the output of the sensor. The external magnetic field is applied perpendicular to the cross-section of the support [1,2].

The disadvantage of this magnetically sensitive sensor is the inability to electrically reset (or control) the inevitable residual parasitic output signal in the absence of a magnetic field (offset), which significantly reduces the measurement accuracy and increases the temperature drift of the output.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a magnetically sensitive sensor with electrically removable (or controllable) offset, minimized temperature drift at the outlet and with increased measurement accuracy.

This problem is solved by a magnetic-sensing sensor containing a semiconductor substrate with impurity type, on one side of which four rectangular ohmic contacts - first, second, third and fourth, parallel to their long sides - are formed on one side at a distance. . The first and third ohmic contacts are connected through a first current source in a mode current generator. The second and fourth ohmic contacts are connected through a second current source in current generator mode. The polarity of the power supply of the second and third ohmic contacts is the same. The outputs of the magnetosensitive sensor are respectively the second and third, and the first and fourth ohmic contacts. The external magnetic field is applied perpendicular to the cross-section of the substrate.

Advantages of the invention are the possibility of electrically controlling (including resetting) the inevitable offset by changing the values of the two currents in the first and second sources, the presence of two equivalent outputs, reduced offset and temperature drift, and increased measurement accuracy.

Description of the attached figures

The invention is illustrated in more detail with the accompanying drawings, where figure 1 is an exemplary embodiment thereof and figure 2 illustrates a schematic solution that minimizes both the offset value and its temperature drift.

Examples of carrying out the invention

The magnetosensitive sensor comprises a semiconductor support 1 with impurity conductivity, on one side of which four rectangular ohmic contacts - first 2, second 3, third 4 and fourth 5, parallel to its long sides - are formed on one side at a distance. The first 2 and the third 4 ohmic contacts are connected through a first current source 6 in current generator mode. The second 3 and fourth 5 ohmic contacts are connected through a second current source 7 in current generator mode. The polarity of the power supply of the second 3 and third 4 ohm contacts is the same. Outputs 8 and 9 are respectively the second 3 and third 4, and the first 2 and fourth 5 ohmic contacts. The external magnetic field 10 is applied perpendicular to the cross-section of the substrate 1.

The action of the magnetosensitive sensor according to the invention is as follows. When the first 6 and second 7 sources are included in the volume of structure 1, two currents 1 _{2 4} and 1 ₃₅ occur. Due to the equipotentiality of the supply ohmic contacts 2.3,4 and 5., the trajectories of currents through them are initially perpendicular to the surface of the substrate 1 and penetrate deeply into its volume. Therefore, the kinetic processes in the sensor are volumetric. The two supply currents 1 _{2 4} and 1 _{3 5} are independent of each other, although they flow in the same region. This is achieved through current generator modes. The external magnetic field 10 induces a Hall effect on the boundary planes by the Lorentz force acting on the two independent currents 1 ₂₄ and 1 _{3 5} . As a result, electrical loads with opposite sign occur simultaneously on the upper surface of the substrate 1, in the zones where contacts 3 and 4, and 2 and 5 are respectively located. Their physical registration is done with the outputs 8 and 9. A specific feature of this converter is that all the sensor contacts 2,3,4 and 5 are both power supply. In order to fully develop the Hall voltages generated in structure 1, the directions of currents must be parallel, i.e. contacts 3 and 4 have the same polarity. The realization of this condition automatically results in the same polarity for the other two ohmic contacts 2 and 5.

In addition to the Hall effect, a magnetoresistive effect occurs in box 1 in structure 1, which is a quadratic and even function of field B. This phenomenon for the Hall sensor should be regarded as parasitic, introducing: strong nonlinear transmission characteristics. However, the two differential outputs 8 and 9 neutralize the common-mode (with the same sign) magnetoresistive signal. Therefore, the equivalent output voltages V, ₄ (B) and V _{2 3} (B) of the new sensor are linear and their sign depends simultaneously on the directions of the magnetic field 10 and the two currents 1 ₂₄ and 1 _{3> 5} . Another important feature of both outputs 8 and 9 is that at fixed directions of the magnetic field 10 and currents 1 _{2 4} and 1 _33, they are inverted, i.e. their polarities are opposite.

The unexpected positive effect of the proposed technical solution is the possibility of neutralizing (zeroing) the completely spurious offset in the absence of the two independent currents 1 ₂ , ₄ and 1 _{3 5} through the supply / Hall contacts 3 and 4 and 2 and 5. magnetic field 10. The main reason for the occurrence of the offset is the inevitable geometric errors in the symmetrical arrangement of the contacts in the technological implementation of the Hall elements. The experiments performed show that the two output characteristics of the new magnetosensitive sensor at the parameter supply currents 1 _{2 4} and 1 _{3 5} realized on the basis of n-Si substrate 1 with a dopant concentration η ~ 10 ¹⁵ sit ³ are linear and odd functions of the magnetic field 10. This proves unambiguously that the action of the new converter is the Hall effect. Both independent currents 1 _{2 4} and 1 _{3 5} make it easy to reset the imminent offset of both outputs 8 and 9. If a particular application requires a fixed offset value (for example, for the purposes of contactless key devices), it is easily established by varying the two currents through current sources 6 and 7. Resetting the offset of both outputs 8 and 9 increases the measurement accuracy of the magnetic induction 10, which is a major advantage for low-field magnetometry. Since the temperature drift of the differential outputs of the magnetic-sensitive semiconductor sensors is proportional to the value of the offset itself, the ability to reset this parasitic residual signal improves by more than an order the temperature stability of outputs 8 and 9.

The presence of two equal but opposite poles outputs 8 and 9 give each other an unexpected opportunity to minimize both its offset and its temperature drift. For the two Hall voltages from outputs 8 and 9, the currents V ₂₄ (B) = '- V ₂₅ (lt) are determined by the currents 1 ₂₄ and 1 ₃₅ . In addition, the generation of the two output signals comes from the same sensor area. For this reason, the offsets of both outputs 8 and 9 are almost the same value. For them, the ratio V _{3 4} (B = 0) V _{2 5} (B = 0) is valid and their temperature drifts are perfectly uniform. In the final output signal, the offset is indistinguishable from the useful magnetic-sensitive signal. Therefore, if the other V _{2 5} (B) is subtracted schematically from one output voltage V ₃₄ (B), then a double running voltage with almost eliminated offset will be obtained: V _H = V _{3 4} (B) - (-V _{3 4} ( B)) = 2V ₃₄ (B) + (V ₃₄ (B = 0) - V ₂₅ (B = 0)). Therefore, the residual offset after subtraction of two output signals is expected to be too low in value. The scheme by which this problem is solved is shown in Figure 2. It comprises the magnetosensitive sensor described above, the two outputs 8 and 9 of which are connected respectively to the two inputs of two operational amplifiers 11 and 12. Outputs 13 and 14 of these operational amplifiers 11 and 12 are connected to the input of a third operational amplifier 15, the output 16 of which is the output of the magnetosensitive sensor. The experiments show that the residual offset of the output 16 of the operational amplifier 15 is about two orders of magnitude lower than that of the output 8 or 9, and the temperature behavior of the output 16 is about 20-30 microU / ° C, which is also about two orders of magnitude lower than the sensor's own output drift 8 or 9.

The industrial implementation of the new Hall sensor with a parallel axis of magnetic sensitivity is based on standard silicon planar technology. Various modifications to CMOS processes and micromachining can also be used, limiting the active conversion region and leading to the further miniaturization of the magnetosensitive sensor. A promising semiconductor material is also n-GaAs.

Claims (2)

Claims 1. A magnetic sensing sensor comprising a semiconductor conductor of impurity type mixed on one side of which four rectangular ohmic contacts, first, second, third and fourth, parallel to their long sides, are formed alternately at distances from one another. the first and third ohmic contacts are connected through a first current source and the external magnetic field is applied perpendicular to the cross-section of the substrate, characterized in that the second (3) and fourth (5) ohmic contacts are connected or through a second power source (7), the power source (6) and (7) being in the current generator mode, where the polarity of the power supply of the second (3) and third (4) ohmic contacts coincide and the outputs (8) and ( 9) of the magnetosensitive sensor are respectively the second (3) and third (4), and the first (2) and fourth (5) ohmic contacts. A magnetosensitive sensor according to claim 1, characterized in that its two outputs (8 and 9) are connected respectively to the two inputs of two operational amplifiers (11 and 12), such as the outputs (13 and 14) of these operational amplifiers (11 and 12) are connected to the input of a third operational amplifier (15), the output (16) of which is the output of the magnetosensitive sensor.