JP7075121B2 - Evaluation method and evaluation device for electronic products - Google Patents

Description

The present invention relates to an evaluation method and an evaluation device for an electronic product configured by using an electronic device.

In an electronic product in which an electronic circuit or the like using a semiconductor element or the like is configured, for example, noise generated during the operation of a motor or the like may be superimposed on a power supply line, a signal line, or the like, causing a malfunction.
As noise that causes a malfunction in an electronic circuit or the like, for example, there is first transient burst noise (hereinafter referred to as EFT / B noise).
This EFT / B noise is a voltage fluctuation that occurs between the reference potential (reference ground) and the circuit wiring in the circuit unit or the like, and is the high potential side wiring constituting the circuit unit or the like and the low potential side such as the signal ground. It is noise superimposed on both wirings. Therefore, for example, a common mode filter or the like is provided at an appropriate portion of the circuit wiring and reduced.

In order to suppress the influence of EFT / B noise, some power supplies for communication devices are provided with a surge absorption nonlinear element or the like (see, for example, Patent Document 1). In this technique, a surge absorption nonlinear element is interposed between the G wire of the return wire of the DC power supply and the E wire of the ground wire, and the noise voltage generated between the G wire and the E wire is clamped. Further, it has a capacitance that delays the rise time of the fast transient noise, thereby effectively absorbing and suppressing the fast transient noise superimposed on or contained in the electric power supplied to the communication device.

Further, in the EMC evaluation of devices such as ICs and LSIs, the DPI (Direct Power injection) method is standardized, and a high frequency noise signal (differential mode noise) is input to the above device, and the device is in accordance with the DPI method. There is a technique for evaluating the malfunction durability of the above (see, for example, Patent Document 2).
In this technology, did the controller that controls the DPI test oscillate a high-frequency signal and inject it into the device, causing pulse omission, frequency disturbance, output voltage out-of-specification, communication error, etc. in the operation of the device? It determines whether or not it is.
In the DPI test, the above controller sweeps the frequency of the high-frequency signal to obtain the calculation result of the injection power (high-frequency signal) at the time when the above-mentioned malfunction occurs, and obtains the frequency of the high-frequency signal and the injection power when the malfunction occurs. The malfunction power frequency characteristic associated with is sought.

Japanese Patent No. 3329987 Japanese Patent No. 6283174

When using the above-mentioned common mode filter, there is no index as to how much the common mode noise should be suppressed. Therefore, there are many cases where a wide variety of noise attenuation filter elements and the like are provided in the circuit, which causes a problem that it becomes difficult to miniaturize electronic products as the cost increases.

The present invention has been made in view of the above problems, and uses an electronic product evaluation method and a method for clarifying a noise frequency that causes a malfunction of an electronic product and determining a level index for reducing noise. It is an object of the present invention to provide an evaluation device.

The method for evaluating an electronic product according to the present invention includes a first process in which a noise source injects a common mode noise frequency into a transmission line provided in the electronic product while sweeping, and prepares the electronic product via the transmission line. The second process of measuring the frequency characteristic indicating the noise level of the common mode noise injected into the terminal of the device at each frequency and the durability characteristic indicating the noise level at each noise frequency at which the device malfunctions are acquired. It is characterized by having a third process and a fourth process of specifying a frequency band of the common mode noise that causes a malfunction in the electronic product from the frequency characteristics and the durability characteristics.

Further, in the fourth process, when the characteristic curve showing the frequency characteristic and the characteristic curve showing the durability characteristic are shown in the graph of frequency on the horizontal axis and noise level on the vertical axis, the frequency characteristic curve is the durability characteristic. It is characterized in that a frequency band having a noise level equal to or higher than a curve is specified as a frequency band that causes a malfunction in the electronic product.

Further, in the first process, common mode noise having the same amplitude and the same phase is injected into the two transmission lines of the electronic product from the noise source, and the second process is connected to the two transmission lines, respectively. It is characterized in that the frequency characteristic is acquired by measuring the potential difference between the two terminals of the device.

Further, the evaluation device according to the present invention includes a noise source that injects a common mode noise frequency into a transmission line provided in the electronic product while sweeping, and a terminal of the device provided in the electronic product via the transmission line. The measuring unit includes a measuring unit that measures the common mode noise injected into the device, and the measuring unit has an input unit that inputs common mode noise from the terminal of the device and converts it into data of a predetermined format, and an output unit from the input unit. A control unit that performs predetermined arithmetic processing using the generated data is provided, and the control unit acquires data representing frequency characteristics indicating the noise level at each frequency of common mode noise input from the terminal of the device. At the same time, data representing the durability characteristics indicating the noise level at each noise frequency at which the device malfunctions is acquired, and the data representing the frequency characteristics and the data representing the durability characteristics are used to obtain the electron. It is characterized in that the frequency band of the common mode noise that causes a malfunction in the product is specified.

Further, when the control unit shows the characteristic curve indicating the frequency characteristic and the characteristic curve indicating the durability characteristic in a graph in which the horizontal axis is the frequency and the vertical axis is the noise level, the frequency characteristic curve is the durability characteristic curve. The frequency band having the above noise level is extracted by the calculation using each of the above data, and is specified as the frequency band that causes the electronic product to malfunction.
It is characterized by that.

Further, the noise source injects common mode noise having the same amplitude and the same phase into the two transmission lines of the electronic product, and the measuring unit is the two devices of the device connected to the two transmission lines, respectively. It is characterized in that the frequency characteristic is acquired by measuring the potential difference between the terminals.

According to the present invention, it is possible to identify a frequency that causes a malfunction of an electronic product, and it is possible to efficiently reduce noise by taking measures suitable for the frequency.

It is explanatory drawing which shows the schematic structure of the evaluation apparatus according to the Example of this invention. It is explanatory drawing which shows the frequency characteristic measured by the evaluation apparatus of FIG. It is explanatory drawing which shows the durability characteristic of the device of FIG. It is explanatory drawing which shows the frequency band specified as the cause of malfunction of an electronic product.

Hereinafter, an embodiment of the present invention will be described.
(Example)
FIG. 1 is an explanatory diagram showing a schematic configuration of an evaluation device according to an embodiment of the present invention. This evaluation device uses a noise source 12 such as an oscillator that outputs high-frequency signals of each frequency, and a measuring device 11 that detects noise signals and the like from each part of the electronic product 10 and converts them into data in a predetermined format for arithmetic processing. It is configured.
The noise source 12 is configured to output two high frequency signals, the above high frequency signals can be adjusted to a desired amplitude magnitude (signal level), and the phases of the two signals can be adjusted. It is configured to be able to. Further, it is configured so that the frequency of the high frequency signal can be swept in a desired frequency band.

The measuring device 11 includes a probe 20 that detects (inputs) a high-frequency noise signal from a desired portion of the electronic product 10. The probe 20 is a high withstand voltage differential probe corresponding to, for example, a common mode voltage of 2 [kV].
The measuring device 11 has, for example, a spectrum analyzer function, and includes an input unit 21, a CPU, a DSP (Digital Signal Processor), and the like that convert high-frequency signals such as common mode noise input using the probe 20 into data in a predetermined format. A control unit 22 equipped with a processor to perform predetermined data processing, calculation, etc., a storage unit that stores data, control programs, etc. used for calculation processing of the control unit 22, and also stores calculation results, etc. performed by the control unit 22. It is equipped with 23 and so on.

For example, the control unit 22 processes data sequentially input from the input unit 21, generates data representing each characteristic described later, and performs arithmetic processing using these data to obtain the above characteristic curve. It is configured to obtain a predetermined area or the like.
The operation processing related to each characteristic curve or the like, which will be described later, is performed by the control unit 22 by arithmetic processing or the like using data representing each characteristic or the like.

The electronic product 10 to be evaluated includes an electronic circuit in which a circuit element or the like such as a device 30 is mounted on a substrate (not shown) and the above circuit elements or the like are connected by a wiring pattern or the like formed on the substrate. There is.
The device 30 is a semiconductor integrated circuit element such as an IC or an LSI, and is configured to include a plurality of terminal pins.
The device 30 illustrated in FIG. 1 includes a Vd pin 31 of a power supply terminal pin for inputting electric power from the outside, an SG pin 32 connected to a ground portion (signal ground) of an internal circuit of the device 30, and the like. The Vd pin 31 is connected to a transmission line 121 provided inside the electronic product 10. Further, the SG pin 32 is connected to a transmission line 122 provided inside the electronic product 10. Neither the transmission lines 121 nor 122 are connected to the reference ground 120.

Next, the operation will be described.
When evaluating the electronic product 10, first, when EFT / B noise invades the electronic product 10, the potential difference generated on the above-mentioned substrate on which the device 30 or the like is mounted or inside the electronic product 10 is measured. Observe.
As shown in FIG. 1, the observation of this potential difference is a noise source on the transmission lines 121 and 122 (transmission lines of the common mode voltage inside the electronic product 10) connected to the Vd pin 31 and the SG pin 32 of the device 30, respectively. 12 is connected. Further, the probe 20 is brought into contact with or connected to the Vd pin 31 and the SG pin 32.

As described above, each part is connected to put the electronic product 10 into an operating state, a noise signal is output from the noise source 12, and the potential difference between the terminal pins (potential difference V3 shown in FIG. 1) is input to the measuring device 11. The waveform is observed and the magnitude of the potential difference is measured.
In the measurement of this potential difference, the frequency of the noise signal generated by the noise source 12 is swept, and the signal strength at which the electronic product 10 malfunctions is measured at each frequency.
When this measurement is performed, noise signals of the same phase with the same magnitude are output from the noise source 12 to the transmission line 121 and the transmission line 122, and common mode noise is injected into the electronic product 10.

In the evaluation device illustrated in FIG. 1, the noise signal of the voltage V1 is output from the noise source 12 to the transmission line 121, and the noise signal of the voltage V2 is output to the transmission line 122.
Here, the voltage V1 and the voltage V2 output from the noise source 12 are potential differences generated between each output terminal of the noise source 12 and the reference ground 120, and have the same amplitude at the output terminal of the noise source 12. The magnitude (same noise level).

FIG. 2 is an explanatory diagram showing frequency characteristics measured by the evaluation device of FIG. In this figure, the amplitude of the noise signal input to the transmission lines 121 and 122 is set to a predetermined magnitude (constant magnitude), and when the frequency of the noise signal is swept, the Vd pin 31 of the device 30 observed at each frequency is 31. It shows the potential difference V3 between and SG pin 32.
In the figure, the horizontal axis shows the frequency of the noise signal output from the noise source 12, and the vertical axis shows the potential difference V3 (noise level injected into the device 30) observed between the Vd pin 31 and the SG pin 32. Shows.

Further, in the figure, the characteristic curve a shows the above-mentioned pin spacing of the device 30 when a noise signal (EFT / B noise) having an amplitude magnitude (noise level) that causes a malfunction in the electronic product 10 is input to each transmission line. The frequency characteristics measured in are shown.
Further, the characteristic curve b is measured between the above-mentioned pins of the device 30 when a noise signal (EFT / B noise) having an amplitude that allows the electronic product 10 to operate normally is input to each of the above-mentioned transmission lines. The frequency characteristics are shown.

When evaluating the electronic product 10, the frequency characteristics described above are acquired, and the durability characteristics (immunity characteristics) of the device 30 by the DPI method described below are acquired.
When measuring the durability characteristics of the device 30 against noise, for example, an evaluation board of the device 30 (not shown) is used. The evaluation board is provided with a predetermined terminal or the like, and an external power supply device is connected to the predetermined terminal so as to supply power to the device 30. Further, for example, a noise source 12 (for example, a noise source 12 (directive coupler) is inserted into a predetermined terminal of the evaluation board so that a high frequency signal (EFT / B noise) is injected into the Vd pin 31 of the device 30. RF modulator etc.) is connected. Further, for example, the measuring device 11 (RF power meter or the like) is connected to the evaluation board via the above-mentioned directional coupler.

Each part is connected as described above, and a high frequency signal is directly injected from the noise source 12 to, for example, the Vd pin 31 and the SG pin 32 of the device 30. At this time, the potential difference V3 between the Vd pin 31 and the SG pin 32 is measured.
Specifically, first, without operating the device 30 of the evaluation board, for example, a noise signal having a predetermined intensity is supplied to a noise input terminal (noise injection port or the like) provided on the evaluation board, and at this time, the measuring device 11 Gets the measured value indicated by. This measured value is obtained at each noise frequency, and the transmission characteristics of the transmission line from the noise input terminal of the evaluation board to the measuring device 11 via the directional coupler are measured.

After that, power is supplied to the evaluation board or the like to put the device 30 into an operating state, the strength (noise level) of the noise signal output from the noise source 12 is changed, and the noise level at which the device 30 malfunctions is measured. ..
The noise level at which the device 30 acquired here causes a malfunction is a value obtained by adding the above-mentioned transmission characteristics to the measured value.

FIG. 3 is an explanatory diagram showing the durability characteristics of the device 30 of FIG. This figure shows the characteristic curve c of the durability characteristic against noise of the device 30 measured by the DPI method as described above. For example, the common mode is applied to the Vd pin 31 and the SG pin 32 of the device 30 mounted on the evaluation board. The vertical axis shows the noise level when noise is injected and a malfunction occurs in the device 30, and the horizontal axis shows the noise frequency when a malfunction occurs at the noise level.
For example, the control unit 22 of the measuring device 11 shown in FIG. 1 measures the frequency characteristics of the electronic product 10 as described above, and acquires, for example, data representing the characteristic curve a of the frequency characteristics shown in FIG. In addition, data representing the characteristic curve c of the durability characteristic is acquired by the above-mentioned DPI method.

The durability characteristics of the device 30 may be actually measured using the measuring device 11 or the like as described above, but data representing the durability characteristics can be acquired from the outside of the measuring device 11 and, for example, a storage unit 23 or the like. It may be stored in advance and read from the storage unit 23 when the control unit 22 is used for arithmetic processing.
After acquiring the durability characteristics of the device 30, the control unit 22 uses the data representing the frequency characteristics (characteristic curve a) and the durability characteristics (characteristic curve c) described above to use the noise frequency band for which noise countermeasures are required for the electronic product 10. Performs processing (arithmetic processing, etc.) to specify.

FIG. 4 is an explanatory diagram showing a frequency band specified as a cause of malfunction of the electronic product 10. This figure is a graph showing the characteristic curves a and b in FIG. 2 and the characteristic curves c in FIG. 3 with the same scales on the vertical axis and the horizontal axis.
For example, when each characteristic curve is shown in the above graph, the control unit 22 extracts a frequency band in which the characteristic curve a is equal to or higher than the characteristic curve c with respect to the noise level, and specifies this as a frequency band requiring noise countermeasures. ..

That is, the control unit 22 obtains the region d shown in FIG. 4 by arithmetic processing or the like, and extracts the frequency band corresponding to the region d.
The region d is a region where the noise level that causes the electronic product 10 to malfunction exceeds the durability characteristics of the device 30 acquired by the DPI method.

Since the EFT / B noise in the frequency band indicated by this region d causes a malfunction in the electronic product 10, an element or the like (for example, a bypass capacitor) that emits common mode noise in the frequency band to, for example, the reference ground 120. May be provided at an appropriate position on the electronic product 10.
Further, when noise countermeasures are applied to the electronic product 10, it is preferable to suppress the noise level in the frequency band of the region d to be lower than the noise level indicated by the characteristic curve c (durability characteristic of the device 30). In this way, when the control unit 22 obtains the region d, it is possible to determine the level index when noise reduction of the electronic product 10 is performed.

10 Electronic products 11 Measuring equipment 12 Noise source 20 Probe 21 Input unit 22 Control unit 23 Storage unit 30 Device 31Vd pin 32SG pin 120 Reference ground 121,122 Transmission line

Claims (6)

The first process in which the noise source injects the frequency of common mode noise into the transmission line provided in the electronic product while sweeping it.
The second process of measuring the frequency characteristic indicating the noise level at each frequency of the common mode noise injected into the terminal of the device provided in the electronic product via the transmission line, and the second process.
The third process of acquiring the durability characteristic indicating the noise level at each noise frequency at which the device malfunctions, and
A fourth process of identifying the frequency band of the common mode noise that causes a malfunction in the electronic product from the frequency characteristics and the durability characteristics, and
A method for evaluating an electronic product, which comprises. The fourth process is
When the frequency characteristics are shown in the first graph in which the horizontal axis is each frequency of the common mode noise and the vertical axis is the noise level at each frequency of the common mode noise, the characteristic curve shown in the first graph. Is the frequency characteristic curve,
The second graph shows the durability characteristics when the horizontal axis represents each noise frequency at which the device malfunctions and the vertical axis represents the noise level at each frequency at which the device malfunctions. When the characteristic curve shown in is taken as the durability characteristic curve,
A frequency band in which the frequency characteristic curve has a noise level higher than or higher than the durability characteristic curve is specified as a frequency band that causes a malfunction in the electronic product.
The method for evaluating an electronic product according to claim 1. The first process is
The common mode noise having the same amplitude and the same phase is injected from the noise source into the two transmission lines of the electronic product.
The second process is
The frequency characteristic is acquired by measuring the potential difference between the two terminals of the device connected to each of the two transmission lines.
The method for evaluating an electronic product according to claim 1 or 2, wherein the method is characterized by the above. A noise source that injects the frequency of common mode noise into the transmission line provided in electronic products while sweeping it.
A measuring unit that measures the common mode noise injected into the terminals of the device provided in the electronic product via the transmission line, and a measuring unit.
Equipped with
The measuring unit
An input unit that inputs the common mode noise from the terminal of the device and converts it into data in a predetermined format.
A control unit that performs predetermined arithmetic processing using the data output from the input unit, and
Equipped with
The control unit
The data showing the noise level at each frequency of the common mode noise input from the terminal of the device is acquired, and the durability characteristic showing the noise level at each noise frequency at which the device malfunctions is shown. Get the data,
Using the data representing the frequency characteristics and the data representing the durability characteristics, the frequency band of the common mode noise that causes a malfunction in the electronic product is specified.
An evaluation device characterized by that. The control unit
When the frequency characteristics are shown in the first graph in which the horizontal axis is each frequency of the common mode noise and the vertical axis is the noise level at each frequency of the common mode noise, the characteristic curve shown in the first graph. Is the frequency characteristic curve,
The second graph shows the durability characteristics when the horizontal axis represents each noise frequency at which the device malfunctions and the vertical axis represents the noise level at each frequency at which the device malfunctions. When the characteristic curve shown in is taken as the durability characteristic curve,
A frequency band in which the frequency characteristic curve has a noise level higher than or higher than the durability characteristic curve is extracted by an operation using the respective data, and is specified as a frequency band that causes a malfunction in the electronic product.
The evaluation device according to claim 4, wherein the evaluation device is characterized by the above. The noise source is
The common mode noise having the same amplitude and the same phase is injected into the two transmission lines of the electronic product.
The measuring unit
The frequency characteristic is acquired by measuring the potential difference between the two terminals of the device connected to each of the two transmission lines.
The evaluation device according to claim 4 or 5.

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