JP2020143898A - Common mode noise transmission path estimation device - Google Patents

Abstract

To provide a common mode noise transmission path estimation device capable of estimating a common mode noise transmission path with less time and effort.SOLUTION: A common mode noise transmission path estimation device estimates a transmission path of common mode noise that enters each terminal of an electronic device 80, and includes: an impedance measuring unit 10 that measures impedance between each pair of terminals 0, 1, 2, and 3; a circuit analysis unit 20 that substitutes impedance into an equivalent circuit model and calculates a current value flowing through each element of the equivalent circuit model; an input/output path estimation unit 30 that estimates the transmission path through which common mode noise is easily transmitted based on a distribution rate of the current value calculated by the circuit analysis unit 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for evaluating common mode noise that invades an input / output port of an electronic device.

Conventionally, a method of measuring a magnetic field generated from a semiconductor such as an IC or an LSI has been proposed for the purpose of measuring and visualizing a transmission path of common mode noise invading from the outside in an internal inner path of an electronic device. (For example, Non-Patent Document 1). This method is a method of measuring the magnetic field strength by a magnetic field probe arranged in the vicinity of the target electronic device at the timing when common mode noise is applied from a specific port.

By repeating as many times as the number of measurement points and mapping the magnetic field strength at each measurement point, the transmission path of the invading common mode noise is visualized. Common mode noise is noise in which a noise source exists between the signal line and the ground and affects both the signal line and the ground line.

Etsuhiro Shiratori, 3 others, "EMC Visualization Solution: Visualization of Noise and Static Electricity", Electromagnetic Environmental Engineering Information, EMC. No. 341, pp.103-113, 2016

In the method disclosed in Non-Patent Document 1, it is necessary to repeat the application of noise and the magnetic field measurement for the number of measurement points. When evaluating the relationship between the noise application timing and the magnetic field strength, it takes more time to evaluate because the processing on the spatial and time axes also overlaps.

For example, for an electronic device with a size of 20 cm x 20 cm, the measurement range of the magnetic field probe is 5 cm x 5
Even if the Cm is roughly set, 24 measurements are required, which is a problem that requires a lot of time and effort.

The present invention has been made in view of this problem, and an object of the present invention is to provide a common mode noise transmission path estimation device capable of estimating a common mode noise transmission path with less time and effort.

The common mode noise transmission path estimation device according to one aspect of the present invention is a common mode noise transmission path estimation device that estimates the transmission path of common mode noise that penetrates into each terminal of the electronic device, and is a common mode noise transmission path estimation device for each of the terminals. An impedance measuring unit that measures the impedance between them, a circuit analysis unit that substitutes the impedance into the equivalent circuit model and calculates the current value flowing through each element of the equivalent circuit model, and a current value calculated by the circuit analysis unit. The gist is to include an input / output path estimation unit that estimates a transmission path in which common mode noise is easily transmitted based on the distribution rate of.

According to the present invention, the transmission path of common mode noise can be estimated with less time and effort.

It is a figure which shows the functional structure example of the common mode noise transmission path estimation apparatus which concerns on 1st Embodiment of this invention. It is a flowchart which shows the schematic processing procedure of the common mode noise transmission path estimation apparatus shown in FIG. It is a figure which shows the equivalent circuit model of the electronic device shown in FIG. It is a figure which shows typically the state of measuring the impedance between terminals of an equivalent circuit model with an impedance analyzer. It is a figure which shows the modification of the equivalent circuit model shown in FIG. It is a figure which shows typically the output example of the input / output path estimation part shown in FIG. It is a functional block diagram which shows the structural example of a part of the impedance measuring apparatus which made it possible to automatically measure each impedance which constitutes the equivalent circuit model shown in FIG. It is a figure which shows the functional structure example of the common mode noise transmission path estimation apparatus which concerns on 2nd Embodiment of this invention. It is a functional block diagram which shows the specific configuration example of the electronic device shown in FIG. It is a figure which shows typically the plurality of paths formed by the functional block shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are given to the same objects in a plurality of drawings, and the description is not repeated.

[First Embodiment]
FIG. 1 is a diagram showing a functional configuration example of the common mode noise transmission path estimation device according to the first embodiment of the present invention. The common mode noise transmission path estimation device 100 shown in FIG. 1 is a device that estimates the transmission path of common mode noise (hereinafter, may be abbreviated as noise) invading each terminal of the electronic device 80.

Each terminal is a positive power supply terminal 1, a negative power supply terminal 0, an input terminal 2, and an output terminal 3 of the electronic device 80. The common mode noise transmission path estimation device 100 includes an impedance measurement unit 10, a circuit analysis unit 20, and an input / output path estimation unit 30. The positive power supply terminal 1 and the negative power supply terminal 0 may be referred to as power supply terminals or terminals. Further, the input terminal 2 and the output terminal 3 may be referred to as input / output terminals or terminals.

The impedance measuring unit 10 can be replaced with a general impedance analyzer. The circuit analysis unit 20 and the input / output path estimation unit 30 can be realized by, for example, a computer including a ROM, a RAM, a CPU, and the like. That is, the common mode noise transmission path estimation device 100 can be realized by a configuration in which an impedance analyzer and a personal computer are combined. In that case, the processing content of the function that the common mode noise transmission path estimation device 100 should have is described by a program. This also applies to other embodiments described later.

FIG. 2 is a flowchart showing a schematic processing procedure of the common mode noise transmission path estimation device. The impedance measuring unit 10 measures the impedance between the terminals of the electronic device 80 (step S1).

The circuit analysis unit 20 substitutes the impedance measured by the impedance measurement unit 10 into the equivalent circuit model, and calculates the current value flowing through each impedance of the equivalent circuit model (step S2).

The input / output path estimation unit 30 estimates that the common mode noise is easily transmitted based on the distribution rate of the current value calculated by the circuit analysis unit 20 (step S3).

FIG. 3 is a diagram showing an equivalent circuit model of the electronic device 80. As shown in FIG. 2, the electronic device 80 can be represented by six impedances. The six impedances are impedance Z ₁₂ between the positive power supply terminal 1 and the input terminal 2, impedance Z ₁₃ between the positive power supply terminal 1 and the output terminal 3, impedance Z ₀₂ between the negative power supply terminal 0 and the input terminal 2. Impedance Z ₀₃ between the negative power supply terminal 0 and the output terminal 4, impedance Z ₀₁ between the negative power supply terminal 0 and the positive power supply terminal 1, and impedance Z ₂₃ between the input terminal 2 and the output terminal 3. In the following, the impedance position in the equivalent circuit model will be indicated by a subscript, and the description between what and what will be omitted.

The equivalent circuit model shown in FIG. 2 can be replaced with the equivalent circuit model shown in FIG. Each impedance shown in FIG. 2 and each impedance shown in FIG. 3 are represented by the relationship shown in the following equation.

(Impedance measurement method)
FIG. 4 is a diagram schematically showing how the value of impedance Z ₁₂ is measured. When measuring the value of impedance Z ₁₂ as shown in FIG. 4, for example, an impedance analyzer is connected between the positive power supply terminal 1 and the input terminal 2 for measurement. The circuit symbol of the signal source shown in FIG. 4 is a signal generator 11 that generates a known signal included in the impedance analyzer.

In this case, the path of the signal emitted by the signal generator 11 is only the impedance Z ₁₂ . Therefore, the value of impedance Z ₁₂ can be accurately measured without being affected by other impedances. In addition, the values of impedances Z ₂₃ and Z ₀₁ can also be measured.

In this way, an impedance analyzer is connected between the terminals of the electronic device 80, and the impedance between the terminals is measured.

The impedance measuring unit 10 obtains the value of each impedance constituting the equivalent circuit model (FIG. 2) of the electronic device 80 by the above measuring method. The impedance measuring unit 10 and the electronic device 60 may be connected by an operator or automatically. The automatic method will be described later.

The circuit analysis unit 20 substitutes the impedance measured by the impedance measurement unit 10 into the equivalent circuit model, and calculates the current value flowing through each impedance of the equivalent circuit model. Each current value is obtained by calculating the amount of scalar input / output at each branch point on the circuit by the contact method based on the circuit theory (Kirchhoff's first and second laws, etc.).

The input / output path estimation unit 30 estimates that the common mode noise is easily transmitted based on the distribution rate of the current value calculated by the circuit analysis unit 20.

As described above, the common mode noise transmission path estimation device 100 according to the present embodiment is a common mode noise transmission path estimation device that estimates the transmission path of common mode noise that penetrates into each terminal of the electronic device 80. An impedance measuring unit 10 that measures the impedance between the terminals of the electronic device 80, a circuit analysis unit 20 that substitutes the impedance into the equivalent circuit model and calculates the current value flowing through each element of the equivalent circuit model, and a circuit. It is provided with an input / output path estimation unit 30 that estimates a transmission path through which common mode noise is easily transmitted based on the distribution rate of the current value calculated by the analysis unit 20. As a result, the transmission path of common mode noise can be estimated with less time and effort.

Common mode noise transmits many paths with low impedance. For example, it is assumed that the impedance Z ₀₂ is a very small value, the impedance Z ₁₃ is a very large value, and the other impedances Z ₁₂ , Z ₀₁ , Z ₂₃ , and Z ₀₃ are medium values.

FIG. 6 is a diagram schematically showing a noise transmission path. The thickness of the arrow shown in FIG. 6 schematically indicates the magnitude of the common mode noise.

As shown in FIG. 6, in the case of this example, since the value of impedance Z ₀₂ is very small, the common mode noise is mainly transmitted between the input terminal 2 and the negative power supply terminal 0. The input / output route estimation unit 30 may display an image schematically showing a transmission route as shown in FIG. 8 on a display device (not shown) of a personal computer. Alternatively, the value of each impedance may be displayed numerically.

Next, a case where the measurement performed by the impedance measuring unit 10 is automatically performed will be described. When the above impedance measurement is automatically performed, a multiplexer that switches the connection between the signal generator 11 of the impedance analyzer and each terminal of the electronic device 80 is required.

FIG. 7 is a diagram showing a part of functional blocks of an impedance measuring device capable of automatically measuring each impedance constituting an equivalent circuit model of the electronic device 80. In this case, the impedance measuring unit 10 includes a multiplexer 12.

The multiplexer 12 connects a signal source (signal generator 11) that generates a known signal for measuring impedance between the power supply terminals 1 and 0 and the input / output terminals 2 and 3 of the electronic device 80. The multiplexer 12 is composed of, for example, a plurality of relays for switching and connecting the signal generator 11 to each terminal of the electronic device 80.

The multiplexer 12 connects the signal generator 11 to terminals 1-2, terminals 2-0, terminals 3-0, terminals 1-3, terminals 1-0, and terminals 2-3, respectively. Switching of the multiplexer 12 is performed by a control unit (not shown). The control unit can be easily realized by a program implemented in a personal computer constituting the common mode noise transmission path estimation device 100.

As described above, the impedance measuring unit 10 includes a multiplexer 12 for connecting a signal source for generating a known signal for measuring impedance between each of the power supply terminal and the input / output terminal of the electronic device 80. This makes it possible to automate the measurement of impedance between each of the terminals of the electronic device 80.

[Second Embodiment]
FIG. 8 is a diagram showing a functional configuration example of the common mode noise transmission path estimation device according to the first embodiment of the present invention. The common mode noise transmission path estimation device 200 shown in FIG. 8 is different from the common mode noise transmission path estimation device 100 (FIG. 1) in that the transmission path estimation unit 40 is provided.

The transmission path estimation unit 40 acquires the information of the functional configuration block of the electronic device 80 and the information corresponding to the impedance values of the functional configuration blocks from the outside, and the two terminals estimated by the input / output path estimation unit. A plurality of paths are formed to connect each of them with a functional configuration block, the impedance of each formed path is obtained, the current distribution rate is calculated from the obtained impedance, and the path having the maximum current distribution rate is the transmission path. And.

Information on the functional configuration block of the electronic device 80 is obtained from a spec sheet or the like of the electronic device 80. Further, the impedance value of each functional configuration block may be obtained from, for example, the current consumption value of each functional configuration block described in the spec sheet.

FIG. 9 is a diagram showing an example of a specific functional configuration block of the electronic device 80. As shown in FIG. 9, the electronic device 80 includes a power supply circuit 81, a communication IC 82, a CPU 83, a memory 84, and a communication IC 85.

FIG. 10 is a diagram showing a plurality of paths between the input terminal 2 and the negative power supply terminal 0 by the impedance of each functional configuration block. Z _CIC1 is the impedance of the communication IC82. The Z _CPU is the impedance of the _CPU 83. Z _Mem is the impedance of the memory 84. Z _CIC2 is the impedance of the communication IC 82. The impedance of each of these functional blocks is obtained from a spec sheet or the like.

As shown in FIG. 10, between the input terminal 2 and the negative power supply terminal 0, a path passing only the communication IC ₈₂ indicated by Z _CIC1-1 , and a path passing through the communication IC ₈₂ and the _{CPU 83 in} which Z _CIC1-2 and Z _{CPU_1} are connected in series. , Z _CIC1-2 , Z _{CPU_2,} and Z _Mem are connected in series, and Z _CIC1-2 , Z _{CPU_3,} and Z _CIC1-2 are connected in series.

The transmission path estimation unit 40 obtains the impedance for each path, calculates the current distribution rate from the obtained impedance, and sets the path having the maximum current distribution rate as the transmission path. For example, it is assumed that the impedance Z CIC1 of the communication IC ₈₂ is the smallest. In this case, the common mode noise transmits a path passing only through the communication IC ₈₂ indicated by Z _CIC1-1 . The route may be displayed on a display device or the like with the size of an arrow or the like as shown in FIG.

As described above, the common mode noise transmission path estimation device 200 according to the present embodiment includes a transmission path estimation unit 40. The transmission path estimation unit 40 acquires information on the functional configuration block of the electronic device and information corresponding to each impedance value of the functional configuration block from the outside, and the two terminals estimated by the input / output path estimation unit. A plurality of paths are formed by connecting the intervals with the functional configuration blocks, the impedance of each formed path is obtained, the current distribution rate is calculated from the obtained impedance, and the path having the maximum current distribution rate is described. Estimated as a transmission path. As a result, the path transmitted by the common mode noise can be estimated in detail.

As described above, according to the common mode noise transmission path estimation devices 100 and 200 according to the present embodiment, the common mode noise transmission path can be estimated with less time and effort.

It goes without saying that the present invention includes various embodiments not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention relating to the reasonable claims from the above description.

0, 1, 2, 3: Terminal 10: Impedance measurement unit 11: Signal source (signal generator)
20: Circuit analysis unit 30: Input / output route estimation unit 40: Transmission route estimation unit 80: Electronic device 100, 200: Common mode noise transmission path estimation device

Claims (3)

It is a common mode noise transmission path estimation device that estimates the transmission path of common mode noise that enters each terminal of an electronic device.
An impedance measuring unit that measures the impedance between each of the terminals,
A circuit analysis unit that substitutes the impedance into the equivalent circuit model and calculates the current value flowing through each element of the equivalent circuit model.
A common mode noise transmission path estimation device including an input / output path estimation unit that estimates a transmission path in which common mode noise is easily transmitted based on a current value distribution rate calculated by the circuit analysis unit. Information on the functional configuration block of the electronic device and information corresponding to each impedance value of the functional configuration block are acquired from the outside, and the functional configuration block is located between the two terminals estimated by the input / output path estimation unit. A plurality of paths to be connected to each other are formed, the impedance of each of the formed paths is obtained, the current distribution rate is calculated from the obtained impedance, and the path having the maximum current distribution rate is estimated to be the transmission path. The common mode noise transmission route estimation device according to claim 1, further comprising a route estimation unit. The impedance measuring unit
The common according to claim 1 or 2, wherein a multiplexer for connecting a signal source for generating a known signal for measuring impedance is provided between the power supply terminal and the input / output terminal of the electronic device. Mode noise transmission path estimation device.

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