A high frequency near field current sensor and probe

Abstract

The present invention provides a high-frequency near-field current sensor and probe, including: a measuring coil, a shielding shell and a signal processing module, wherein: the measuring coil is used to closely contact the device to be tested to obtain a high-frequency induction signal, wherein the placement angle of the measuring coil is perpendicular to the working current direction of the device to be tested; the shielding shell is arranged outside the measuring coil to insulate and protect the measuring coil; the signal processing module is connected to the output end of the measuring coil to eliminate the error of the high-frequency induction signal to obtain the working current parameters of the device to be tested in the first time. It can directly measure the high-frequency current of the wiring of the circuit board and the pins of the patch device, and obtain the working current parameters of the device to be tested in the first time, which has great practical value for the optimization design of the device to be tested. It has a simple structure, easy operation and wide applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor design and application, and in particular to a high-frequency near-field current sensor and a probe. Background Art

[0002] Current probes are electrical devices used to measure direct current and alternating current, such as high-speed transient, pulse current or industrial frequency sinusoidal current. Current probes include ultra-high frequency and high bandwidth coaxial non-inductive shunts, Pearson coils, oscilloscope AC and DC high frequency probes, Hall devices and Rogowski coils (coils named after German physicist Walter Rogowski). Among them, the advantage of high frequency and high bandwidth coaxial non-inductive shunts is that they have excellent performance and can measure DC signals at the GHz bandwidth level. The disadvantage is that they must be connected in series to the circuit to be tested, which restricts the test environment; the advantage of Pearson coils is that they do not need to be connected in series to the circuit to be tested and have good isolation. The disadvantage is that they are too large and difficult to measure micro-circuit systems; the disadvantage of oscilloscope AC and DC high frequency probes is that they are too large and difficult to measure micro-circuit systems, and the range is limited; Hall devices are difficult to use in high frequency environments; Rogowski coils are currently the most flexible and convenient high-frequency current measurement tools, with a minimum wire diameter of 1 mm, which can be easily covered on the wires or semiconductor pins of most devices to be tested. However, for the wiring of printed circuit boards and the test environment of the pins of surface mount devices, Rogowski coils cannot perform high-frequency current measurements.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a high-frequency near-field current sensor and probe to solve the problem in the prior art that it is difficult to measure high-frequency current on the wiring of the circuit board and the pins of the surface-mount device.

[0005] To achieve the above-mentioned object and other related objects, the present invention provides a high-frequency near-field current sensor, which at least includes: a measuring coil, a shielding shell and a signal processing module, wherein:

[0006] The measuring coil is used to closely contact the device under test to obtain a high-frequency induction signal, wherein the placement angle of the measuring coil is perpendicular to the working current direction of the device under test;

[0007] The shielding shell is arranged outside the measuring coil to provide insulation protection for the measuring coil;

[0008] The signal processing module is connected to the output end of the measuring coil and performs error elimination on the high-frequency induction signal to obtain the working current parameters of the device under test in the first place.

[0009] Optionally, the measuring coil comprises an air-core coil.

[0010] Optionally, the measuring coil The maximum width of the cross section is between 0.5 mm and 1.5 mm.

[0011] Optionally, the number of turns of the measuring coil is between 100 and 1000 turns.

[0012] Optionally, the cross-section of the measuring coil has a shape including: circle, rectangle, regular hexagon, regular octagon, and ellipse.

[0013] Optionally, the bandwidth of the high frequency induction signal is between 10 Hz and 200 MHz.

[0014] Optionally, the device under test includes: wiring of a printed circuit board and pins of a surface mount device.

[0015] Optionally, the allowable operating temperature of the shielding shell is greater than or equal to 105 degrees Celsius.

[0016] Optionally, the signal processing module includes an integration processing circuit.

[0017] To achieve the above-mentioned object and other related objects, the present invention provides a probe, which includes the high-frequency near-field current sensor and is used to measure the working current parameters of the device to be measured.

[0018] As described above, a high-frequency near-field current sensor and a probe of the present invention have the following beneficial effects:

[0019] 1) The high-frequency near-field current sensor and probe of the present invention can directly measure the high-frequency current of the wiring of the circuit board and the pins of the surface-mount device, and obtain the working current parameters of the device to be tested in the first time, which has great practical value for the optimization design of the device to be tested.

[0020] 2) The high-frequency near-field current sensor and probe of the present invention have simple structure, easy operation and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown is a schematic structural diagram of an exemplary Rogowski coil of the present invention.

[0022] Figure 2 Shown is a schematic diagram of a high-frequency near-field current sensor of the present invention.

[0023] Figure 3 Shown is a schematic diagram of the measured waveform of the high-frequency near-field current sensor of the present invention.

[0024] Figure 4 Shown is a schematic diagram of the measured waveform of the probe of the present invention.

[0025] Description of Reference Numerals

[0026] 11 Rogowski coil

[0027] 2 High frequency near field current sensor

[0028] 21 Measuring coil

[0029] 22 Signal Processing Module

[0030] 23 Device under test DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] See also Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are only schematic illustrations of the basic concept of the present invention. The illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0033] Figure 1The schematic diagram of the structure of the Rogowski coil is shown. The conventional Rogowski coil is set in the form of uniform coil winding on a non-magnetic frame of constant cross-sectional area. The non-magnetic frame and the coil wound on the non-magnetic frame together form a Rogowski coil 11. The coil returns to the starting point along the central axis of the non-magnetic frame. The starting point of the coil outputs an induction signal, and the device to be tested is a conductor. The alternating or pulsed current in the conductor generates a magnetic field, and the interaction between the magnetic field and the Rogowski coil causes the Rogowski coil to generate an induction signal, which is proportional to the rate of change of the current generated by the conductor to be tested. In order to obtain an output voltage proportional to the induction signal, an integrator is usually connected at the starting point. The integrator integrates the induction signal to obtain the output voltage. The output voltage proportional to the induction signal is linear in the entire broadband, and the broadband is defined as the frequency range from the starting frequency to the cutoff frequency. At low frequencies, the gain of the integrator increases. In theory, as the frequency approaches zero, the gain of the integrator becomes infinite, which will lead to unacceptable DC drift and low-frequency noise; therefore, the gain of the integrator needs to be limited to low frequencies, and this limitation is achieved by connecting a low-pass filter in parallel with the integrating capacitor. Due to the distributed inductance and distributed capacitance of the Rogowski coil, the Rogowski coil is in a high-frequency bandwidth, which is usually 10MHz or higher, so it can measure high-frequency induced signals. The output voltage generated by the integrator is usually detected by a test device, including an oscilloscope. By detecting the output voltage, the operating current parameters of the device under test (such as current waveform and other parameters) are obtained, so as to analyze the performance of the device under test and optimize the device under test. However, the Rogowski coil cannot measure the wiring of the printed circuit board and the pins of the surface mount device.

[0034] Therefore, the present invention provides a high-frequency near-field current sensor and a probe, which are specifically implemented as follows:

[0035] like Figure 2 As shown, this embodiment provides a high-frequency near-field current sensor 2, the high-frequency near-field current sensor 2 comprising: a measuring coil 21, a shielding shell (the shielding shell is not Figure 2 ) and a signal processing module 22, wherein:

[0036] like Figure 2 As shown, the measuring coil 21 is used to closely contact the device under test 23 to obtain a high-frequency induction signal, wherein the placement angle of the measuring coil 21 is perpendicular to the working current direction of the device under test 23. It should be noted that the placement angle of the measuring coil 21 is perpendicular to the working current direction of the device under test 23 in order to enable the measuring coil 21 to obtain the maximum induced magnetic field, and then obtain the maximum induced electric field, so as to perform parameter measurement through the test equipment. The measuring coil 21 is in emergency contact with the device under test 23 in order to minimize the attenuation of the induced magnetic field.

[0037] Specifically, as an example, the measuring coil 21 includes an air-core coil; the maximum width of the cross section of the measuring coil 21 is between 0.5 mm and 1.5 mm. It should be noted that the coil is usually cylindrical, that is, the cross section of the coil is circular, then the maximum width of the cross section of the measuring coil 21 is equal to the outer diameter of the cylinder × 2; if the cross section of the coil is a square, then the maximum width of the cross section of the measuring coil 21 is equal to the side length of the square; if the cross section of the coil is a regular hexagon, then the maximum width of the cross section of the measuring coil 21 is equal to the height of the regular hexagon; the number of turns of the measuring coil 21 is between 100 and 1000 turns; the shape of the cross section of the measuring coil includes: circular, rectangular, regular hexagonal, regular octagonal, elliptical. It should be noted that the air-core coil refers to a coil that does not rely on magnetic materials. Since there is no magnetism, there is almost no core loss in the air-core coil, which makes the air-core coil have low distortion, is not easy to saturate, and has an excellent quality factor (the quality factor can reach 190. Quality factor, that is, Quality Factor is a parameter that describes the performance of the resonator. It refers to the ratio between the storage capacity and capacity of the resonator. The quality factor is a physical quantity used to describe the energy consumption characteristics of a resonant circuit or mechanical system. In a circuit, the quality factor refers to the quality of a capacitor, inductor or resistor. The higher the value, the better the device can store and release energy without loss, which means that the sharper the circuit response is. In a mechanical system, the quality factor describes the vibration response capability of the system. The higher the value, the slower the vibration decay rate of the system and the longer the vibration duration. Furthermore, the quality factor is an important parameter to describe the performance of a resonator. The larger the quality factor, the narrower the response bandwidth when the resonator resonates, that is, it is difficult to carry signals that are too broadband. The quality factor can directly affect the performance indicators of the resonant circuit, such as bandwidth, impedance matching, and output purity. In an electronic circuit system, it is usually necessary to select a suitable quality factor according to specific needs, and adopt corresponding technical means to improve or control the quality factor to achieve better circuit performance) and other characteristics, which are suitable for high-frequency applications. It should be noted that the measuring coil 21 includes but is not limited to an air-core coil, and a high-frequency choke may also be used. As long as it can be used to closely contact the device under test to obtain a high-frequency induction signal, any setting form of the measuring coil 21 is applicable and is not limited to this embodiment.

[0038] Within the constrained range, the mutual inductance and self-inductance of the measuring coil 21 will increase linearly with the increase of the wire diameter (the wire diameter refers to the diameter of the wire of the measuring coil). When it exceeds a certain range, the rate of increase will slow down. At the same time, as the wire diameter of the measuring coil 21 increases, its internal resistance will also increase linearly, and the increase multiples of the mutual inductance and self-inductance are greater than the multiples of the increase of the internal resistance. The equivalent capacitance of the measuring coil 21 will gradually increase with the increase of the wire diameter. When the wire diameter of the measuring coil 21 is small, the number of turns will also be small. The mutual inductance, internal resistance, and self-inductance of the measuring coil 21 first increase and then decrease with the increase of the wire diameter. This is caused by two factors. First, as the wire diameter increases, the cross-sectional area of ​​the measuring coil 21 decreases; second, the increase in wire diameter will gradually increase the number of turns. The reduction in cross-sectional area will reduce the mutual inductance, internal resistance, and self-inductance; the increase in the number of turns will increase the mutual inductance, internal resistance, and self-inductance. The combined effect of these two aspects will first increase and then decrease the mutual inductance, internal resistance, and self-inductance of the measuring coil 21. The equivalent capacitance decreases with the increase of the wire diameter, and the speed of change is getting faster and faster. Therefore, the wire diameter of the measuring coil 21 includes but is not limited to between 0.5 mm and 1.5 mm; the number of turns of the measuring coil 21 includes but is not limited to between 100 turns and 1000 turns. The wire diameter and the number of turns of the measuring coil 21 need to be set according to the actual environment, which will not be described here one by one.

[0039] The shape of the measuring coil 21 affects the uniformity of the induced magnetic field. The more regular its shape is, the better the uniformity of the magnetic field is, and the more stable the intensity of the generated high-frequency induction signal is. Therefore, the shape of the measuring coil 21 includes but is not limited to: circular, rectangular, regular hexagonal, regular octagonal, elliptical. As long as a uniform magnetic field can be generated, any shape of the measuring coil 21 is applicable and is not limited to this embodiment.

[0040] Specifically, as an example, the bandwidth of the high-frequency induction signal is between 10 MHz and 200 MHz. It should be noted that the range of the high-frequency bandwidth is usually 10 MHz or higher, and the frequency of the induction signal is determined by the working current of the device under test and the parameters of the measuring coil 21. The specific working process will not be described here one by one.

[0041] Specifically, as an example, the device to be tested includes: wiring of a printed circuit board, pins of a patch device. It should be noted that due to the special setting of the Rogowski coil, it is impossible to directly measure the wiring of the printed circuit board and the pins of the patch device, thereby limiting the application of the Rogowski coil in a micro integrated circuit system. The high-frequency near-field current sensor of this embodiment can obtain a high-frequency induction signal in the first time by closely contacting the measuring coil 21 with the device to be tested 23, and has great application value.

[0042] The shielding shell is arranged outside the measuring coil 21 to insulate and protect the measuring coil 21. Figure 2. Specifically, as an example, the allowable operating temperature of the shielding shell is greater than or equal to 105 degrees Celsius. It should be noted that the measurement indicator of the shielding shell is the insulation level, and the insulation level specifically refers to the heat resistance level of the shielding shell. The insulation levels are arranged according to the temperature size: Y level, A level, E level, B level, F level, H level and C level, and their allowable operating temperatures are: 90 degrees Celsius, 105 degrees Celsius, 120 degrees Celsius, 130 degrees Celsius, 155 degrees Celsius, 180 degrees Celsius and above 180 degrees Celsius. In addition to being related to the material, the shielding shell is also related to the thickness of the material. Different materials and thicknesses will affect the induced magnetic field that the measuring coil 21 can generate, and then affect the high-frequency induced signal. Therefore, the shielding shell should be set according to the actual situation, and is not limited to this embodiment.

[0043] like Figure 2 As shown, the signal processing module 22 is connected to the output end of the measuring coil 21, and performs error elimination on the high-frequency induction signal to obtain the working current parameters of the device under test in the first time. Specifically, as an example, the signal processing module 22 includes an integration processing circuit. It should be noted that the integration processing circuit is used to integrate the high-frequency induction signal to obtain an output voltage, and its output voltage is proportional to the high-frequency induction signal, and the output signal is easier to observe through the test equipment. Furthermore, the signal processing module 22 can also be set using a fitting circuit, and the specific operation process will not be repeated here one by one. As long as the high-frequency induction signal can be error eliminated to obtain the working current parameters of the device under test in the first time, any setting form of the signal processing module 22 is applicable, and is not limited to this embodiment.

[0044] As an example, Figure 3 The schematic diagram of the measured waveform of the high-frequency near-field current sensor of this embodiment is shown, wherein channel 3 shows the standard waveform when the device under test is working, the device under test is a power device in a patch package, and its standard waveform is fitted by an oscilloscope; channel 1 shows the waveform of the device under test obtained by the high-frequency near-field current sensor described in this embodiment at the first time, which is acquired by an oscilloscope; channel 2 shows the waveform of the device under test acquired by a 30MHz Rogowski coil, wherein, when using the Rogowski coil, the device under test cannot be soldered on the printed circuit board, and it is necessary to measure by extending the three pins of the device under test. It can be seen that the waveform obtained by using the high-frequency near-field current sensor is more similar to the standard waveform, that is, the performance of the high-frequency near-field current sensor described in this embodiment is better than that of the Rogowski coil.

[0045] This embodiment further provides a probe, which includes the high-frequency near-field current sensor described in this embodiment, and is used to measure the working current parameters of the device under test. It should be noted that the device under test includes: wiring of a printed circuit board and pins of a surface mount device.

[0046] As an example, Figure 4 The schematic diagram of the measured waveform of the probe of this embodiment is shown. It can be seen that the waveform of the device under test measured by the probe is almost consistent with the standard waveform, so the probe described in this embodiment has a wide range of application value.

[0047] In summary, a high-frequency near-field current sensor and probe of the present invention include: a measuring coil, a shielding shell and a signal processing module, wherein: the measuring coil is used to closely contact the device to be tested to obtain a high-frequency induction signal, wherein the placement angle of the measuring coil is perpendicular to the working current direction of the device to be tested; the shielding shell is arranged outside the measuring coil to insulate and protect the measuring coil; the signal processing module is connected to the output end of the measuring coil to eliminate the error of the high-frequency induction signal to obtain the working current parameters of the device to be tested in the first time. The high-frequency near-field current sensor and probe of the present invention can directly measure the high-frequency current of the wiring of the circuit board and the pins of the patch device, obtain the working current parameters of the device to be tested in the first time, and have great practical value for the optimization design of the device to be tested. The high-frequency near-field current sensor and probe of the present invention have a simple structure, easy operation, and wide applicability. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A high frequency near-field current sensor, characterized in that: The high-frequency near-field current sensor at least includes: a measuring coil, a shielding shell and a signal processing module, wherein: The measuring coil is close to the device under test in a non-sheathed manner and is located on the side of the device under test; wherein the axial direction of the measuring coil is perpendicular to the working current direction of the device under test, and the axial directions of multiple coils of the measuring coil overlap, so that the measuring coil obtains the maximum induced magnetic field; the bandwidth of the high-frequency induced signal is between 10MHz and 200MHz; The shielding shell is arranged outside the measuring coil to provide insulation protection for the measuring coil; The signal processing module is connected to the output end of the measuring coil, and performs error elimination on the high-frequency induction signal to obtain the working current parameters of the device under test in the first place; The device under test includes: wiring of a printed circuit board and pins of a patch device; the measuring coil includes a plurality of coils wound evenly along a constant cross-sectional area; and the measuring coil is an air-core coil to generate a uniform magnetic field.

2. The high-frequency near-field current sensor according to claim 1, characterized in that: The maximum width of the cross section of the measuring coil is between 0.5 mm and 1.5 mm.

3. The high frequency near-field current sensor according to claim 1, characterized in that: The number of turns of the measuring coil is between 100 turns and 1000 turns.

4. The high frequency near-field current sensor according to claim 1, characterized in that: The cross-section of the measuring coil may have a shape including: circle, rectangle, regular hexagon, regular octagon, and ellipse.

5. The high frequency near-field current sensor according to claim 1, characterized in that: The allowable operating temperature of the shielding shell is greater than or equal to 105 degrees Celsius.

6. The high frequency near-field current sensor according to claim 1, characterized in that: The signal processing module includes an integration processing circuit.

7. A probe, characterized in that: The probe comprises the high-frequency near-field current sensor according to any one of claims 1 to 6, and is used to measure the operating current parameters of the device to be measured.

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