JP2004257770A - High-frequency electric potential detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To bring a sharp probe into contact with each part to be measured including a via detection terminal on a circuit board surface layer, and to easily detect the high-frequency potential quantity thereon. <P>SOLUTION: When a sharp probe 311 of a primary side cylindrical metal conductor 31 is brought into contact with a potential detection terminal 21, a via detection terminal 21 or the like on the circuit board 1, an antenna current flows in the primary side cylindrical metal conductor 31. A current proportional to the antenna current is detected by a secondary side balanced shield loop coil 33 through a ferrite ring 32, and the current is observed by a measuring device 4 through a cable 34, for example, as a state converted into a voltage. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a high-frequency potential detecting device for detecting a high-frequency potential amount at each part to be measured.
[0002]
[Prior art]
2. Description of the Related Art Recently, circuit boards mounted on various electronic devices have been further densified and multilayered. Therefore, once problems such as EMI (electromagnetic interference) and EMS (electromagnetic Susceptibility) occur, In fact, it is extremely difficult to solve these problems. This means that when the phenomenon is observed, it is necessary to measure the current and voltage at various measurement site positions on the circuit board. This is because it is necessary to perform operations such as cutting the current, inserting an ammeter, or replacing parts.
[0003]
Incidentally, Patent Document 1 discloses an annular core through which a line to be measured passes, a current detection coil wound around the annular core, and a load resistor connected to both ends of the current detection coil. There is described a current detection device including an output line provided with a common mode choke filter for guiding a voltage generated at the load resistance to a measurement device.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 10-185962
[Problems to be solved by the invention]
However, in practice, the measurement probe is large, and therefore cannot be inserted between two points, or the circuit may be damaged or destroyed due to erroneous operation, or in the worst case, it may not be repairable. . Observing phenomena inside the multilayer circuit board in addition to such defects on the surface layer has become even more difficult, and much time and labor has been required.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a high-frequency potential amount in each of the measured portions easily by simply bringing a sharp probe into contact with each of the measured portions on the circuit board without changing the mounting state on the circuit board. It is an object of the present invention to provide a high-frequency potential detecting device that can be detected and observed / measured.
[0007]
[Means for Solving the Problems]
The high-frequency potential detecting device according to the present invention includes a thin primary-side bar-shaped metal conductor corresponding to an antenna, one end of which is a sharp probe contacted with a portion to be measured, and a ferrite ring connected to the primary-side bar-shaped metal conductor. A converter that directly and indirectly detects a physical quantity proportional to the antenna current by means of a secondary-side balanced shield loop coil that is magnetically coupled to the measuring device while the physical quantity detected by this converter is kept shielded. And a guiding cable, so as to be configured as a high-frequency potential probe.
[0008]
For example, even if the measured portion is inside the circuit board, if the measured portion is formed in advance as a detection via terminal on the surface layer via a via wire, the primary-side bar-shaped metal conductor has a sharp probe. Simply contacting the detection via terminal as well as the portion to be measured and the potential detection terminal on the surface layer will function as an antenna. As a result, a physical quantity (current or voltage) proportional to the antenna current is easily detected from the converter, and is observed by a measuring device via a cable, so that it is easy to take measures against radiated disturbance and susceptible disturbance, and the like. It can be dealt with promptly.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
First, the outline of the high-frequency potential detecting device according to the present invention will be described. FIG. As shown in the figure, the high-frequency potential detecting device is used as a state interposed between a circuit board (in this example, a multilayer circuit board) 1 and a measuring device (for example, a spectrum analyzer) 4. Although a detailed configuration will be described later, a thin primary-side bar-shaped metal conductor (its axial length is variable) 31, a ferrite ring 32, a secondary-side balanced shield loop coil 33, and a cable (a low-impedance coaxial cable) 34 And so on. Incidentally, the ferrite ring 32 and the secondary-side balanced shield loop coil 33 are configured as a converter for detecting a physical quantity proportional to the antenna current.
[0010]
When the sharp probe 311 of the primary rod-shaped metal conductor 31 is brought into contact with the potential detection terminal 21 on the circuit board 1, an antenna current flows through the primary rod-shaped metal conductor 31, but is proportional to the antenna current. The current is detected by the secondary-side balanced shield loop coil 33 via the ferrite ring 32. The current is observed by the measuring device 4 via the cable 34 in a state where the current is further converted to a voltage by a resistor, for example.
[0011]
FIG. 1 (B) also shows the primary side even if the measured part is inside the circuit board 1 and the measured part is formed in advance as a detection via terminal 22 on the surface layer via a via wire. Just by bringing the sharp probe 311 of the rod-shaped metal conductor 31 into contact with the detection via terminal 22, the state at the site to be measured inside the circuit board 1 is observed by the measuring device 4 in the same manner as in the case of FIG. It is possible.
[0012]
Now, specifically explaining the high-frequency potential detecting device, FIGS. 2A and 2B show a front view and a plan view of one example. As shown in the drawing, the primary-side bar-shaped metal conductor 31 has one end formed as a sharp probe 311, and the converter 5 has a state in which the primary-side bar-shaped metal conductor 31 penetrates the inside thereof, The primary-side bar-shaped metal conductor 31 is mounted on the primary-side bar-shaped metal conductor 31 so that the mounting position in the axial direction is variable. In other words, the relative position of the converter 5 and the primary-side bar-shaped metal conductor 31 in the axial direction is variable, so that the current distribution in the axial direction of the primary-side bar-shaped metal conductor 31 is observed. It is possible. Incidentally, in FIGS. 2A and 2B, reference numeral 341 denotes a connector for connecting the cable 34 to the measuring device 4.
[0013]
Here, the converter 5 will be described. FIGS. 3 (A) and 3 (B) respectively show schematic longitudinal and transverse cross sections of the inside. As shown in the drawing, a secondary-side balanced shield loop coil 33 composed of loop coils 3311, 3312, 3321, and 3322 is wound around the ferrite ring 32 (this balanced shield loop coil 33). For the principle of the antenna, refer to “Antenna Engineering Handbook” (see the shielded loop antenna described in Ohm Co., Ltd., Oct. 30, 1980, pages 62 and 63). Although the coil 33 and the primary-side bar-shaped metal conductor 31 are in an insulated state, they are magnetically coupled via the ferrite ring 32, and generate an induced electromotive force in the secondary-side balanced shield loop coil 33, thereby forming a loop. Part of the current is output to the cable 34. Actually, the current flows through the one-turn loop coil. Is passed through the low resistance 35, and the voltage drop at the low resistance 35 is observed by the measuring device 4 via the cable 34. Incidentally, the low resistance 35 functions to stabilize the sensitivity characteristic with respect to frequency. I have.
[0014]
Next, the inside of the converter 5 will be described. In the state where the guide pipe 36 accommodating the primary-side bar-shaped metal conductor 31 is directly and indirectly fixed to the ferrite ring 32, the primary-side bar-shaped metal conductor 31 is fixed. The relative positional relationship between the primary rod-shaped metal conductor 31 and the converter 5 can be made variable in the axial direction so that the distribution of current flowing on the primary-side rod-shaped metal conductor 31 can be observed. 5 can be fixed by screwing screws 37.
[0015]
The high-frequency potential detecting device according to the present invention has been described above. However, actually, there is a possibility that extraneous noise flows on the cable 34 and flows into the outer conductor, a part of which flows into the original signal line, and becomes an interference wave. As a countermeasure for this, as shown in FIG. 4, an appropriate number of ferrite rings 38 may be attached near the end of the cable 34 on the converter 5 side. This is because if a common mode current is to flow through the outer conductor of the cable 34, the impedance of the ferrite ring 38 increases and the common current is blocked. Therefore, by forming a common mode filter by the ferrite ring 38, unnecessary components are blocked and absorbed, and stabilization can be achieved.
[0016]
Here, the operation and action of the high-frequency potential detecting device of the present invention as a common mode high-frequency potential probe will be briefly described. Prior to this, it was confirmed that the high-frequency potential detecting device mainly functions as a potential probe. Keep it. As a potential probe, the length of the primary-side bar-shaped metal conductor 31 is shortened, made capacitive (capacitive), and used at high impedance. This is because the measured voltage is small and is measured stably.
[0017]
First, as shown in FIG. 5, the four-layered multilayer circuit board is illustrated as a modeled state, but if the sharp probe 311 is brought into contact with the detection via terminal 22 on the surface layer, the primary The current flowing through the side bar-shaped metal conductor 31 is detected by the converter 5 and is observed via a cable 34 by a spectrum analyzer as the measuring device 4. By the way, when describing the multilayer substrate, G is a beta land as the lowermost layer, s is a signal line as a microstrip line, P is a signal source, and U is a via from the signal line s to the detection via terminal 22. The line indicates the resistance, and r indicates the resistance.
[0018]
FIG. 6 also shows the output characteristics of the spectrum analyzer when the frequency sweep is performed with the voltage at the signal source P set to constant voltages P1 and P2 (> P1) in the state shown in FIG. Is shown. As shown in the figure, the peak point (maximum point) of the curve shows a state where the length of the primary-side bar-shaped metal conductor 31 resonates at approximately １ ／ wavelength and ／ wavelength, respectively.
[0019]
Similarly, in the state shown in FIG. 5, the output characteristics of the spectrum analyzer when the frequency sweep is performed with the length of the primary-side bar-shaped metal conductor 31 set to L1 and L2 (≒ 4L1), respectively. As shown in FIG. As shown in the figure, no resonance state is recognized when the length is L1, but when the length is set to L2, the peak point of the high-frequency current can be read, and the two points (points F1 and F2) can be read. From the resonance state, it can be seen that the primary rod-shaped metal conductor 31 is well represented as an antenna.
[0020]
From the above phenomena, it is possible to easily and quickly measure and observe the high-frequency potential amount simply by bringing the sharp probe 311 into contact with the measurement site.
[0021]
Finally, FIG. 8 shows a circuit configuration as an application example of the present invention. As shown, a circuit including resistors R1, R2, and R3, a capacitor C, an amplifier A, and a coil L is shown. When such a circuit is mounted at a high density, if the operation of the circuit is to be checked and the voltage or current at each of the points a to f is to be measured, there is no gap for inserting the measurement electrode, and the measurement is performed. Is extremely difficult. However, when the detection via terminal for each of the points a to f is previously provided on the surface layer at the stage of forming the circuit, the potential at each of the points a to f can be easily measured. That is, the measurement makes it possible to predict the voltage drop or the current from the potential difference, and therefore, it is also possible to easily estimate and judge the operation phenomenon, so that early measures and countermeasures can be taken.
[0022]
As described above, the high-frequency potential detecting device of the present invention is provided with the primary-side bar-shaped metal conductor as an antenna, and the sharp probe is brought into contact with a detection via terminal or the like as a part to be measured. The operating potential and the like at the measurement site can be easily observed without changing the mounting state of components and the like, so that not only the phenomenon can be quickly clarified but also a countermeasure can be taken promptly.
[0023]
In addition, if a sharp probe is brought into contact with components, conductor patterns, connector terminals, etc. on the surface layer, the potential etc. can be easily observed, and it is also possible to observe the potential etc. via the detection via terminal. It has become. In other words, when a pattern to be measured is present inside the substrate (inner layer) when designing the pattern of the circuit board, if the detection via terminal is provided on the surface layer via the via line from the measured position, the substrate itself or It is possible to easily observe the potential and outflow disturbance current at the measured part without causing any damage to the parts, and it is possible not only to estimate the phenomena in the inner layer, but also to take appropriate measures promptly. Become.
[0024]
Furthermore, in the resonance phenomenon inside the electronic device, radiation of electromagnetic interference is strong near the frequency, and some countermeasures are often required. Such phenomena include not only resonance in a lumped constant circuit, but also resonance between layers of a substrate, particularly between a ground and a power supply layer, and cavity resonance in a shield housing. In such a case, portions having different potentials are distributed on the metal conductor plate, but if the scanning is performed by moving the sharp probe, the ground is pulled out to a position where the radiation amount is small due to the situation of the potential peak or valley. Positions can also be provided.
[0025]
As described above, the use of the high-frequency potential detection device of the present invention makes it possible not only to detect abnormal phenomena in a short time and without waste, but also to reduce the amount of interference by taking appropriate measures. It becomes. It can be used not only for radiation disturbance phenomena, but also for analysis and elucidation of high-frequency phenomena at the time of susceptibility disturbance measures and development design of transceivers.
[0026]
As described above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be variously modified without departing from the gist thereof. Needless to say, there is.
[0027]
【The invention's effect】
Without changing the mounting state on the circuit board, the high-frequency potential at each of the measured parts can be easily detected and observed simply by bringing the sharp probe into contact with each of the measured parts on the circuit board. / A high-frequency potential detecting device capable of measurement is provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a use state of a high-frequency potential detecting device according to the present invention as a relationship between a measuring device and a circuit board.
FIG. 2 is a diagram showing a front view and a plan view of an example of the high-frequency potential detecting device.
FIG. 3 is a view schematically showing a vertical section and a horizontal section inside a converter as a component thereof.
FIG. 4 is a diagram showing a configuration of a high-frequency potential detecting device of the present invention in which measures against external noise are taken into consideration.
FIG. 5 is a diagram for explaining the operation and action of the high-frequency potential detecting device of the present invention as a common mode potential probe.
6 is a diagram illustrating output characteristics of the spectrum analyzer when frequency sweep is performed in a state where voltages at the signal source illustrated in FIG. 5 are set to different constant voltages.
7 is a diagram showing output characteristics of a spectrum analyzer when frequency sweep is performed in a state where the primary-side bar-shaped metal conductors shown in FIG. 5 are set to different lengths.
FIG. 8 is a diagram showing a circuit configuration as an application example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Multilayer board, 4 ... Measuring device, 5 ... Converter, 22 ... Potential detection terminal, 22 ... Via detection terminal, 31 ... Primary side bar-shaped metal conductor, 311 ... Sharp probe, 32, 38 ... Ferrite ring, 33 ... Secondary side balanced type shield loop coil, 34 ... Cable (low impedance coaxial cable), 35 ... Low resistance

Claims (4)

A primary rod-shaped metal conductor corresponding to an antenna, one end of which is a sharp probe that is in contact with a measurement site;
The primary rod-shaped metal conductor penetrates through the inside of the ferrite ring, and is entirely attachable to an arbitrary position in the axial direction of the primary rod-shaped metal conductor. A transducer configured to detect a physical quantity proportional to the antenna current by a secondary balanced shield loop coil magnetically coupled to the metal conductor;
A high-frequency potential detecting device including a cable for guiding the physical quantity detected by the converter to the measuring device in a shielded state. The high-frequency potential detecting device according to claim 1,
A high-frequency potential detection device in which the physical quantity is detected as a current or a voltage when the current flows through a resistor. The high-frequency potential detecting device according to claim 1,
A high-frequency potential detecting device in which the primary-side bar-shaped metal conductor has a variable axial length. The high-frequency potential detecting device according to claim 1,
A high-frequency potential detecting device having a ferrite ring attached near the converter end of the cable.

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