KR20130068354A - Channel switching device, impedance measuring system, and controlling method thereof - Google Patents

Abstract

PURPOSE: A channel switch device, an impedance measurement system, and a controlling method thereof are provided to check signal transfer capability by measuring the impedance of a device under test. CONSTITUTION: A channel switch device(30) includes a first connection units(33,34) which receive an input signal for measurement; a second connection unit(a1-d1,a2-d2) which is comprised of multiple channels which are connected with a measured electronic component; a control unit(31) outputs the input signal for measurement through one of the multiple channels of the second connection unit by an instruction which is received from a host machine; and a communication unit which transmits an instruction by being connected with the host machine. [Reference numerals] (31) Control unit; (32) Level shifter; (33) First switch; (34) Second switch; (AA) First connection unit; (BB) First channel; (CC) Second channel; (DD) Third channel; (EE) Fourth channel; (FF) Second connection unit

Description

CHANNEL SWITCHING DEVICE, IMPEDANCE MEASURING SYSTEM, AND CONTROLLING METHOD THEREOF}

The present invention relates to a channel switching device, an impedance measuring system, and a method of controlling the same, which are used to measure the impedance of a device under measurement to confirm signal transmission capability.

There are several methods of measuring impedance, but in general, the instrument transmits a signal to the transmission line of the device under measurement and measures the time of the signal reflected back from the PCB. By converting the time difference when the signal is reflected back from the PCB, the impedance of the signal line of the device under measurement can be calculated.

It has taken considerable time to ascertain the signal transfer characteristics of the device under measurement through a conventional impedance measurement device. This is because in order to measure the impedance of the device under measurement through various channels, the user has to measure the impedance by manually changing each channel, and each channel needs to be calibrated for each channel change. . In particular, in changing the channel, a measuring jig having a plurality of channel terminals was used, and the channel terminal of the measuring jig could be physically damaged due to frequent channel changes. In addition, there is a time distortion and a DC offset in the impedance measurement method. To compensate for this, there are measurement errors for each measurement device and each measurement time, while the user manually adjusts the toggle cursor of the impedance measurement device. In addition, there is an inconvenience in that the user has to check the impedance measurement data while manually adjusting the scale of the graph displayed on the monitor of the impedance measuring device.

One aspect of the present invention provides a channel switching device for automatically switching a channel connecting the impedance measuring device and the device under measurement. In addition, an aspect of the present invention is an impedance measuring the impedance of the device under measurement while automatically switching channels, performing a calibration measurement to automatically correct the time distortion and DC offset, and outputs a user-friendly graph according to the measurement result A measurement system and a control method thereof are provided.

The channel switching device according to an embodiment of the present invention for this purpose transmits the measurement input signal to the electronic component to be mounted on the printed circuit board of the device to be measured, and by using the feedback signal fed back A channel switching device of an impedance measurement device for generating impedance measurement data, the channel switching device comprising: a first connection portion for receiving the measurement input signal, a second connection portion including a plurality of channels connected to the electronic component under measurement, and received from a host device And a control unit for causing the measurement input signal to be output through one of a plurality of channels of the second connection unit by an instruction, and a communication unit connected with the host device to transmit the instruction.

In addition, the first connection unit transmits the feedback signal to the impedance measuring device, and the impedance measuring device generates the measurement data based on the feedback signal.

The first connection unit receives a plurality of measurement input signals from a plurality of measurement ports of the impedance measuring device.

The communication unit is a general-purpose serial bus, and supplies driving power for the channel switching device.

The measurement data may be generated based on a time difference between the time when the input signal for measurement is transmitted and a time when the feedback signal is received.

In the impedance measurement system according to an embodiment of the present invention, in the impedance measurement system, the measurement input signal is transmitted to the electronic component to be mounted on the printed circuit board of the device under measurement, and the feedback signal is returned using the feedback signal fed back. An impedance measuring apparatus for generating impedance measurement data of a measuring electronic component, one terminal of which receives a measuring input signal of the impedance measuring apparatus, and the other terminal of the channel switching apparatus connected to the measuring electronic component through a plurality of channels; And controlling the channel switching device to connect the impedance measuring device and the electronic component under measurement through one of the plurality of channels, and measuring the impedance to measure the impedance of the electronic component under measurement through the connected channel. It includes a host device for controlling the device.

The host device is connected to the impedance measuring device through a local area network, the host device transmits setting information to the impedance measuring device, and the impedance measuring device transmits measurement data to the host device.

The host device is connected to the impedance measuring device through a universal interface bus, the host device transmits a control command to the impedance measuring device, and the impedance measuring device transmits measurement data and status information to the host device. do.

The host device is also connected with the channel switching device via a universal serial bus, and the host device sends a control command to the channel switching device and supplies driving power.

The host device may further include a display configured to display a graph corresponding to the measured data of the impedance measuring device.

In addition, the host device automatically adjusts the scale of the graph and displays an effective section of the measurement data.

In the control method of the impedance measuring system according to an embodiment of the present invention, an impedance measuring apparatus, one terminal of which receives an input signal for measuring the impedance measuring apparatus, and the other terminal of which is connected to the electronic component under measurement through a plurality of channels. A control method of an impedance measurement system comprising a channel switching device, and a host device for controlling the impedance measuring device and the channel switching device, wherein the channel switching device is connected to the impedance measuring device through one of the plurality of channels. And the electronic component to be measured, the impedance measuring apparatus measures the impedance of the electronic component under measurement through the connected channel, and the host device displays a graph according to the measurement data of the impedance measuring apparatus.

In addition, measuring the impedance automatically corrects the time distortion of the impedance measurement data measured by the impedance measuring device by the host device.

In addition, measuring the impedance automatically corrects the DC offset of the impedance measurement data measured by the impedance measuring device by the host device.

In addition, displaying the graph calculates a design value of a signal line formed on a printed circuit board on which the electronic component under measurement is mounted according to the measurement data.

In addition, displaying the graph may cause the host device to adjust the scale of the graph based on the length of the signal line according to the design value, and display a valid section of the measurement data.

According to one aspect of the present invention described above it is possible to automatically switch the channel connecting the impedance measuring device and the device under measurement, so that the measurement time is reduced than when the user manually changes the channel. In addition, the time required for measuring impedance through all channels is reduced by performing the calibration at the first time without the user having to perform the calibration every time each channel is changed. In addition, since the channel is automatically switched while the measuring jig is connected to the channel switching device, the risk of physically breaking the measuring jig due to the channel change is reduced. In addition, since the impedance measuring apparatus is set according to the setting information, and the time distortion and the DC offset are automatically corrected, the measurement error for each operator and each measurement cycle can be reduced. In addition, a user-friendly graph is output according to the measurement result, so that the user can quickly check the valid section and the measurement data of the device under measurement.

1 is a schematic connection diagram of an impedance measurement system according to an embodiment of the present invention
2 is a schematic block diagram of a host device according to an embodiment of the present invention;
3 is a schematic block diagram of a channel switching apparatus according to an embodiment of the present invention;
4 is a schematic flowchart of a control method of an impedance measurement system according to an embodiment of the present invention;
5 is a schematic diagram illustrating a method of correcting time distortion and a DC offset according to an embodiment of the present invention.
6 to 7 are schematic diagrams for explaining a method of displaying an effective section of measurement data according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a schematic connection diagram of an impedance measurement system according to an embodiment of the present invention.

Referring to FIG. 1, the impedance measuring system includes an impedance measuring device 10 measuring impedance of the device under measurement 40, a channel switching device 30 connected to the impedance measuring device 10 and the device under measurement 40. And a host device that controls the channel switching device 30 and the impedance measurement device 10.

The impedance measuring apparatus 10 may measure the impedance of the device under measurement 40 through an oscilloscope and a sampling module and generate impedance measurement data. The impedance measuring device 10 transmits a signal to a signal line of the device under measurement 40, for example, a printed circuit board (PCB), in order to measure the impedance of the device under measurement 40. This is a method of measuring the time when the signal is reflected back from the device under measurement 40. Here, the position and the degree of failure of the PCB can be known through the position of the signal reflected and the degree of change in impedance. More specifically, the sampling module of the impedance measuring apparatus 10 includes a function generator to transmit a step pulse having a fast rise time. And the oscilloscope of the impedance measuring apparatus 10 measures the reflected wave reflected by the measuring apparatus 40 and returning. In general, the impedance measurement through the impedance measuring device 10 is made to confirm the signal transmission capability in the complex circuit of the device under measurement 40 through the impedance distortion of the signal line.

In other words, the impedance measuring apparatus 10 transmits the measurement input signal to the component under measurement mounted on the printed circuit board of the apparatus under measurement 40, and measures the impedance of the electronic component under measurement using the feedback signal fed back. Generate data. In this case, the measurement data is generated based on the time difference between the time when the input signal for measurement is transmitted and the time when the feedback signal is received.

Looking at the impedance measurement results, the measured impedance of the device to be measured 40 is matched with the output impedance of the impedance measuring device 10 so that smooth signal transmission is performed without reflection of a square wave and excessive capacitance component of the signal line. Due to the inductance component, the section where the impedance deviates from the reference value can be identified. That is, the signal is reflected at the discontinuous point of the impedance and causes interference with the transmission signal, resulting in signal distortion. In addition, a part or all of the signal transmitted by the impedance measuring apparatus 10 is reflected at the point where the signal line of the measuring apparatus 40 is opened.

The device 40 to measure impedance through the impedance measuring device 10 includes a high-definition multimedia interface (HDMI), a digital video interactive (DVI), and a universal serial bus (USB). ), A PCB, a connector, a cable, and the like, and a probe used in the impedance measuring apparatus 10 includes a single-end method and a differential method.

The channel switching device 30 is for measuring the impedance of the device under measurement 40 through a plurality of channels. Accordingly, one terminal of the channel switching device 30 is connected to the measurement port of the impedance measuring device 10 to receive the measurement input signal transmitted by the impedance measuring device 10. The other terminal of the channel switching device 30 is connected to the port under measurement of the device under measurement 40, that is, the electronic component of the device under measurement through a plurality of channels. On the other hand, one terminal of the channel switching device 30 is composed of a plurality of terminals to measure the differential signal line can be connected to a plurality of ports, that is, the first port and the second port of the impedance measuring apparatus 10, respectively. have. The channel switching device 30 connects the impedance measuring device 10 and the electronic component under measurement 40 through one of the plurality of channels by an instruction received from the host device 20. In addition, the measurement input signal is output through the connected channel. The channel switching device 30 transmits the feedback signal to the impedance measuring device 10, and the impedance measuring device 10 generates impedance measurement data based on the feedback signal. In addition, the channel switching apparatus 30 may sequentially or arbitrarily connect one channel among the plurality of channels according to the control command of the host device 20. The impedance measuring apparatus 10 may measure the impedance of the device under measurement 40 through the connected channel.

In the related art, a measuring jig having a plurality of channel terminals is used to measure the impedance of the device under measurement 40 through each channel. The plurality of channel terminals of the measuring jig were connected to the measuring port of the impedance measuring apparatus 10 by a high frequency cable. Therefore, in order to measure the impedance of the device 40 to be measured through all channels, there is an inconvenience in that the user manually reconnects each channel terminal of the measuring jig and the high frequency cable, but according to one aspect of the present invention, the user The controller may automatically measure the impedance of the device under measurement 40 through all channels by controlling the host device 20. The detailed structure of the channel switching device 30 will be described in detail with reference to FIG. 3.

The host device 20 controls the overall operation of the impedance measurement system. The host device 20 is connected to the impedance measuring device 10 through a local area network (LAN) and a general purpose interface bus (GPIB). The host device 20 transmits the setting information to the impedance measuring apparatus 10 through the LAN, and transmits a control command to the impedance measuring apparatus 10 through the GPIB. The setting information of the impedance measuring apparatus 10 is information for setting the measurement conditions of the impedance measuring apparatus 10 when the host device 20 is connected to the impedance measuring apparatus 10, and the horizontal axis scale and the vertical axis scale of the measurement data. a scale, a sample interval, a reference value for determining a failure of the apparatus 40 to be measured, and the like. The setting information may be changed according to a user's input in the impedance measuring process of the impedance measuring apparatus 10 and retransmitted to the impedance measuring apparatus 10. In addition, the host device 20 transmits various control commands to the impedance measuring device 10 to transmit an impedance measuring command, receives raw data of measured impedance, or scales the impedance measuring device 10. Etc., or may receive state information of the impedance measuring apparatus 10. The impedance measuring apparatus 10 transmits data regarding the measured image to the host apparatus 20 through the LAN, and transmits the measurement data and state information to the host apparatus 20 through the GPIB. The measurement image transmitted by the impedance measuring apparatus 10 may be an image capturing a measurement screen displayed on the monitor of the impedance measuring apparatus 10. The host device 20 is connected to the channel switching device 30 via a USB. The host device 20 transmits a control command to the channel switching device 30 via USB, and supplies driving power to the channel switching device 30. On the other hand, the driving power of the channel switching device 30 is preferably supplied via USB, it is also possible to be supplied by an external power source. The detailed structure of the host device 20 will be described in detail with reference to FIG. 2.

2 is a schematic block diagram of a host device according to an embodiment of the present invention.

Referring to FIG. 2, the host device 20 may include an input unit 21 for receiving control information from a user, a central processing unit 22 for controlling overall operations of the host device 20, and a display unit for displaying impedance measurement data ( 23). Here, the host device 20 may be configured as a personal computer (PC), for example. Although not shown in FIG. 2, the host device 20 may include a memory unit for storing various information and data.

The input unit 21 includes an input device such as a keyboard or a mouse to receive control information from a user. The user may input a control command to the host device 20 by clicking a control button on the window displayed by the display unit 23 or inputting a control value through a keyboard.

The central processing unit 22 may be connected to a channel switching device and an impedance measuring device to control the overall operation of the impedance measuring system. The central processing unit 22 also performs various arithmetic processing required for the display unit 23 to display the measurement data.

The display unit 23 includes output devices such as an LCD monitor and a PDP monitor to display measurement data. More specifically, the display unit 23 displays a graph corresponding to the measurement data of the impedance measuring device, automatically adjusts and displays the scale of the graph by the arithmetic processing of the central processing unit 22, and displays the effective section of the measurement data. And the like can be additionally displayed. In addition, the display unit 23 displays an impedance change curve of data obtained by calibrating raw data of impedance measured as described below, and displays a point where the magnitude of the impedance is maximum and minimum according to the measurement result. I can display it. In addition, the display unit 23 may display state information, setting information, a measurement result, a measurement history, and the like of the impedance measuring apparatus.

3 is a schematic block diagram of a channel switching apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the channel switching device 30 includes a plurality of switches 33 and 34, a control unit 31 for controlling the switches 33 and 34, and a level shifter 32 for amplifying a control signal of the control unit 31. It is configured to include).

The channel switching apparatus 30 according to an embodiment of the present invention uses 1x4 switches 33 and 34. That is, one terminal of the switches 33 and 34 is composed of one terminal, and the other terminal is composed of four terminals. Therefore, in order to measure the differential signal line of the device under measurement, a plurality of switches 33 and 34 should be used.

One terminal of the first switch 33 is in high frequency connection with the first port of the impedance measuring apparatus, and one terminal of the second switch 34 is in high frequency connection with the second port of the impedance measuring apparatus. More specifically, one terminal of the plurality of switches 33 and 34 and the measuring port of the impedance measuring device are connected via a high frequency cable. The four terminals a1, b1, c1, and d1 on the other side of the first switch 33 and the four terminals a2, b2, c2, and d2 on the other side of the second switch 34 are to be measured. Is connected to the port. More specifically, the other terminals of the plurality of switches 33 and 34 are connected to the port under measurement by an application jig (not shown). Accordingly, the channel switching device 30 is connected to the first connection portion for receiving the measurement input signal transmitted by the impedance measuring device, the electronic component mounted on the printed circuit board of the device under measurement, and the plurality of channels connected through the plurality of channels. 2 connection parts are provided.

The application jig has eight SMA cables. Specifically, one side of the application jig is provided with eight strands of the SMA cable, the other side is provided with a connector that is connected to the terminal to be measured. Herein, the connector may be provided as a connector of various types so as to be connected to various terminals of the device under measurement. That is, the application jig may be provided for each type of the terminal to be measured of the apparatus under measurement. Eight strands of SMA cables are connected to eight terminals on the other side of the plurality of switches 33 and 34, respectively. A pair of two-strand SMA cables corresponds to one channel connecting the measuring port of the impedance measuring device and the measuring port of the measuring device. That is, one terminal on the other side of the first switch 33 and one terminal on the other side of the second switch 34 are combined to form one channel. Accordingly, first to fourth channels are formed between the plurality of switches 33 and 34 and the port under measurement of the device under measurement. On the other hand, the channel switching device 30 according to an embodiment of the present invention formed four channels using a plurality of 1x4 switches 33 and 34, but is not limited thereto and according to the type and number of switches used The number of can be changed. Meanwhile, a micro electronic mechanical system (MEMS) switch having high frequency characteristics may be used for the first switch 33 and the second switch 34. It is also preferable to use a switch of low dielectric constant and low loss.

The controller 31 controls the switches 33 and 34 to connect the measurement port of the impedance measuring apparatus and the port under measurement through one of the plurality of channels. In more detail, the control part 31 controls the switches 33 and 34 according to the control command transmitted from the host device. On the other hand, the host device and the channel switching device 30 are connected via USB. Accordingly, the control unit 31 converts the USB control signal transmitted from the host device into a general purpose input / output (GPIO) control signal and transmits it to the plurality of switches 33 and 34.

The level shifter 32 amplifies the GPIO control signal transmitted from the control unit 31. For example, the GPIO control signal transmitted by the controller 31 uses a logic level of 5 V, but a logic level of 90 V may be used to drive the switch. More specifically, the plurality of switches 33 and 34 according to an embodiment of the present invention include four gate terminals, four source terminals, and one drain terminal. The plurality of switches 33 and 34 represent a high level, that is, a source terminal and a drain terminal are electrically connected to each other in response to a gate terminal to which a voltage of 90 V is applied. That is, in order to drive the switches 33 and 34, a 5 V GPIO control signal is amplified to 90 V and transmitted to the gate terminals of the switches 33 and 34. Meanwhile, a driving voltage for driving the level shifter 32 may be supplied from the controller 31.

Meanwhile, the channel switching device 30 may further include a communication unit (not shown) connected to the host device to transmit an indication of the host device. The communication unit may be configured of USB, and may receive driving power of the channel switching device 30 from the host device.

4 is a schematic flowchart of a control method of an impedance measurement system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, first, a user controls a host device to select a measurement mode (S410). For example, the user may select a measurement mode using a mouse on a window displayed by the display unit of the host device. Impedance measurement modes are divided into single mode and differential mode, and each mode can select port type such as USB, DVI, HMDI, and CUSTOM as detailed mode. According to the user's selection of the measurement mode, the host device transmits setting information for setting measurement conditions to the impedance measuring device. In this way, the impedance measuring apparatus sets the measurement conditions and prepares the impedance measurement of the apparatus under measurement. In addition, the host device may receive information about the device under measurement and the user.

Meanwhile, before the user starts the impedance measurement by controlling the host device, the host device may check the USB connection state of the host device and the channel switching device, the LAN of the host device and the impedance measurement device, and the GPIB connection state.

In operation S420, calibration is performed while automatically switching a plurality of channels of the channel switching apparatus according to a user's selection. The user may instruct the host device to perform a calibration measurement using the input device, and the host device may control the channel switching device to sequentially or randomly activate one of the plurality of channels. That is, according to the automatic switching command of the host device, the channel switching device causes all channels to be connected once, and the impedance measuring device may automatically perform calibration measurements of all channels through the activated channel.

On the other hand, calibration measurements should be made before the other terminal of the channel switching device and the port under test are connected. More specifically, the impedance of the application jig should be measured by connecting the cable of the application jig only to the other terminal of the channel switching device and the connector of the application jig connected to the port to be measured. Therefore, the activated channel is a state in which a signal transmitted by the impedance measuring apparatus is transmitted only to the end point of the signal line of the SMA cable of the application jig without mechanically connecting the port of the device under test and the connector of the application jig. Say. The connector of the application jig is mechanically connected to the port under measurement of the device under measurement, and the channel is connected when the signal transmitted from the impedance measuring device is transmitted to the device under measurement.

Through calibration measurement, the impedance measuring device measures the impedance of the application jig, and can check the section from the measurement port of the impedance measuring device to the end point of the signal line of the application jig, and thus the signal line of the impedance measuring system and the device under measurement Can be separated. In the differential mode, in the calibration measurement process, the host device automatically corrects a time distortion between the measurement data of the first port and the measurement data of the second port. In addition, a process of automatically correcting the DC offset of the measurement data of the impedance measuring apparatus is performed. Such a correction process will be described in detail with reference to FIGS. 6 to 7.

According to the user's selection, the impedance of the device under measurement is measured while automatically switching a plurality of channels of the channel switching device (S430). In the same way as a calibration measurement, the user can instruct the host device to perform an automatic measurement. The channel switching apparatus automatically switches and connects one channel among the plurality of channels under the control of the host apparatus, and the method of measuring the impedance of the apparatus under measurement through the channel to which the impedance measuring apparatus is connected is as described above.

In the meantime, the user may switch manually according to the user's selection without automatically switching a plurality of channels in the calibration measurement (S420) and the impedance measurement (S430) of the device under measurement. The host device transmits a control command to the channel switching device to connect the channel selected by the user, and the channel switching device connects one channel selected by the user among the plurality of channels according to the control command.

When the impedance measurement of the device under measurement is completed, the host device stores the measurement result and outputs a graph according to the measurement data (S440). At the same time, the host device automatically adjusts the scale of the graph and displays the valid section of the measurement data on the graph. According to an aspect of the present invention, a user may check a graph that the display unit of the host device automatically adjusts and displays the scale without directly adjusting the toggle cursor of the impedance measuring device to adjust the scale on the monitor of the impedance measuring device. .

Meanwhile, the host device may output a graph according to the calibration measurement result in the calibration measurement process S420. In this case, first, the impedance change curve is output according to the raw data, and then the impedance change curve is output according to the calibrated data. The user can check the end point of the signal line of the application jig displayed by the host device on the graph.

The host device may calculate an impedance for each stackup structure according to a user's command (S450). That is, the host device can automatically calculate the design value of the signal line formed on the printed circuit board on which the electronic component under measurement is mounted according to the impedance measurement data. To this end, a formula for calculating a design value may be stored in advance in the host device, and the formula may be changed and stored according to a user input. The host device may adjust and display the scale of the graph based on the length of the signal line according to the calculated design value.

The host device generates a report according to the measurement result of the impedance measuring device (S460). More specifically, a report is automatically generated according to the measurement data according to the user's selection. Reports can be generated from commonly used word processors, spreadsheets, and document files.The reports include bibliographic details of impedance measurements, measurement results of the device under measurement, failure results of the device under measurement, and graphs of impedance change curves. The contents of may be included.

5 is a schematic diagram illustrating a method of correcting time distortion and a DC offset according to an embodiment of the present invention.

Referring to FIG. 5, a display unit of a host device displays a graph according to calibration measurement data of an impedance measuring device. The graph shows the impedance change curve with the position from the measurement port of the impedance measuring device to the end point of the application jig. The horizontal axis of the graph represents the sample interval, and the vertical axis represents the magnitude of the impedance. Here, the horizontal axis corresponds to the position of the signal line of the device under measurement.

There is a timing skew between the measurement data (first signal) of the first port of the impedance measuring device and the measurement data (second signal) of the second port. The method for automatically correcting timing skew is as follows. First, the central processing unit of the host device analyzes impedance measurement data of the first port and the second port to find a point where the magnitude of the impedance becomes infinite. On the other hand, since it is difficult to find a point where the magnitude of the impedance actually shows infinity, a reference differential coefficient is used, and a method of using the reference differential coefficient will be described in detail with reference to FIG. 7.

The time offset is calculated based on a difference between a point at which the magnitude of the impedance measured by the first port represents infinity and a point at which the magnitude of the impedance measured by the second port represents infinity. Adjust the timing skew. The display unit of the host device displays the corrected graph according to the measurement data reflecting the time offset.

In addition, the DC offset of the differential data measured by the impedance measuring apparatus may be checked on the impedance change curve of FIG. 5. Here, the DC offset may occur due to the impedance measuring device, the channel switching device, the resistance of the application jig, and the like. As described above, the calibration measurement is a process of connecting the SMA cable of the application jig only to the other terminal of the channel switching device and measuring the impedance without connecting the connector of the application jig to the port to be measured. In this process, the impedance measuring device measures the impedance of the application jig.

The central processing unit of the host device sets an impedance matching the normal impedance of the device under measurement as a reference value. In addition, a DC offset is calculated based on the difference between the magnitude of the impedance measured by the impedance measuring apparatus and the reference value, and the measured data is automatically corrected through the calculated DC offset. The display unit of the host device displays the corrected graph according to the measurement data from which the DC offset is removed. According to an aspect of the present invention, the user can check a graph automatically correcting timing skew and DC offset without directly adjusting a toggle cursor of an impedance measuring device.

6 to 7 are schematic diagrams for explaining a method of displaying an effective section of measurement data according to an embodiment of the present invention.

Referring to FIG. 6, a display unit of a host device displays a graph according to calibration measurement data of an impedance measuring device. The graph of FIG. 6 shows an impedance change curve (jig signal) as a result of automatically correcting the time distortion and the DC offset. In addition, detailed description is abbreviate | omitted about the matter which overlaps with FIG.

As described above, the calibration measurement is a process of connecting the SMA cable of the application jig only to the other terminal of the channel switching device and measuring the impedance without connecting the connector of the application jig to the port to be measured. In this process, the impedance measuring device measures the impedance (jig signal) of the application jig.

The central processing unit of the host device estimates the starting point of the signal line of the device under measurement. Here, since the connector of the application jig is connected to the port under measurement of the device under measurement, the start point of the signal line of the device under measurement coincides with the end line of the application jig. The end line of the application jig corresponds to the point where the signal line is opened and the magnitude of the impedance is infinite. However, it is difficult to find the point where the magnitude of the impedance is infinite. Determine as the end line of. And, while the display unit of the host device automatically adjusts the scale of the graph, the starting point of the signal line of the device under measurement can be moved to a reference point on the graph. For example, the starting point of the signal line of the device under measurement can be moved to 400 sample intervals. The impedance change curve is also moved on the graph with the starting point of the signal line of the device under test. Here, the reference point may be changed according to the user's input. Then, according to the impedance measurement of the device under measurement, the impedance change curve according to the position of the signal line of the device under measurement is displayed from the starting point of the moved signal line.

On the other hand, estimating the start point of the signal line of the apparatus under measurement using the reference differential coefficient is the same as the method of estimating the end point of the signal line, which will be described later.

The display unit of the host device displays a reference value for determining the failure of the device under measurement on the graph. In more detail, the display unit displays a reference line corresponding to an upper limit and a lower limit on the graph, respectively. According to one aspect of the present invention, the user can quickly identify the defective position and the degree of the defective device by comparing the impedance change curve and the reference straight line.

Referring to FIG. 7, the display unit of the host device displays a graph according to the impedance measurement data of the impedance measuring device. The graph shows the impedance change curve according to the position of the signal line of the device under test. In addition, detailed description is abbreviate | omitted about the matter which overlaps with FIG.

First, the effective section of the measurement data is automatically determined using the reference differential coefficients. Here, the effective section means a section from a start line to an end line of the signal line of the device under measurement. The point representing the reference differential coefficient is estimated as the point at which the signal line of the device under measurement is opened, that is, the end line of the signal line of the device under measurement. Here, the reference differential coefficient may be changed according to the user's setting.

The process of calculating the differential coefficient of each point is performed by the central processing unit of the host device, and is performed from right to left based on an impedance change curve (dut signal). For example, the derivative coefficient of each point is sequentially calculated from the point where the magnitude of the impedance is 300 ohms to the start line of the signal line of the device under measurement. When the sequentially calculated differential coefficients initially correspond to the reference differential coefficients, the point is estimated as an end line of the signal line of the device under measurement. Here, the point at which the calculation of the differential coefficient is started may be changed according to the user's setting.

On the other hand, when it is difficult to calculate the differential coefficient, the average rate of change can be calculated. The user may set the reference average change rate corresponding to the size of the interval for calculating the average change rate and the reference differential coefficient.

The host device automatically adjusts the scale of the graph before estimating the end point of the signal line of the device under measurement. For example, when the sample interval on the horizontal axis of the graph is up to 2000 and the impedance magnitude at the point where the sample interval is 2000 is smaller than 300 ohms according to the preset scale of the graph, the scale of the graph can be automatically enlarged and adjusted. . That is, the reference impedance of the maximum point on the horizontal axis of the graph is set according to the user's input. If the impedance of the maximum point on the graph's horizontal axis is smaller than the reference impedance, the scale of the graph is automatically enlarged until it is larger than the reference impedance. Adjust

The host device determines and displays a point max at the maximum of the magnitude of the impedance and a point min at the minimum within the valid period of the measurement data, and displays it on the graph. In addition, the scale of the graph is automatically adjusted and displayed. Therefore, according to an aspect of the present invention, the user can easily check the effective section of the impedance measurement data without directly adjusting the toggle cursor of the impedance measurement apparatus.

10: impedance measuring device 20: host device
30: channel switching device 40: device under measurement

Claims (16)

The input signal for measurement is transmitted to the electronic component to be mounted on the printed circuit board of the apparatus under measurement, and the channel switching device of the impedance measuring apparatus generates impedance measurement data of the electronic component under measurement using the feedback signal fed back. In
A first connector configured to receive the measurement input signal;
A second connecting portion including a plurality of channels connected to the electronic component under measurement;
A controller configured to output the measurement input signal through one of a plurality of channels of the second connection unit according to an instruction received from a host device; And
And a communication unit connected to the host device to transmit the indication. The method of claim 1,
And the first connection unit transmits the feedback signal to the impedance measuring device, and the impedance measuring device generates the measurement data based on the feedback signal. The method of claim 1,
And the first connection unit receives a plurality of measurement input signals from a plurality of measurement ports of the impedance measuring device. The method of claim 1,
And the communication unit is a general-purpose serial bus, and supplies driving power to the channel switching device. The method of claim 1,
The measurement data, the channel switching device, characterized in that generated on the basis of the time difference between the transmission time and the feedback signal is received. In the impedance measurement system,
An impedance measuring device for transmitting an input signal for measurement to an electronic component to be mounted on a printed circuit board of the apparatus to be measured and generating impedance measurement data of the electronic component to be measured using the feedback signal fed back;
A channel switching device having one terminal receiving an input signal for measurement of the impedance measuring device and the other terminal being connected to the electronic component under measurement through a plurality of channels; And
Controlling the channel switching device to connect the impedance measuring device and the electronic component under measurement through one of the plurality of channels, and measuring the impedance of the electronic component under measurement through the connected channel. Host device for controlling the; Impedance measurement system comprising a. The method according to claim 6,
The host device is connected to the impedance measuring device through a local area network, the host device transmits configuration information to the impedance measuring device, the impedance measuring device transmits the measurement data to the host device Measuring system. The method according to claim 6,
The host device is connected to the impedance measuring device via a universal interface bus, the host device transmits a control command to the impedance measuring device, the impedance measuring device transmits measurement data and status information to the host device. An impedance measuring system. The method according to claim 6,
The host device is connected to the channel switching device via a universal serial bus, and the host device sends a control command to the channel switching device and supplies driving power. The method according to claim 6,
The host device further comprises a display unit for displaying a graph corresponding to the measurement data of the impedance measuring device. The method of claim 10,
The host device automatically adjusts the scale of the graph and displays an effective section of the measurement data. Impedance measuring device, one terminal receives the input signal for the measurement of the impedance measuring device, the other terminal is a channel switching device connected to the electronic component under test and a plurality of channels, and the impedance measuring device and the channel switching device In the control method of the impedance measurement system including a host device for controlling,
The channel switching device connects the impedance measuring device and the electronic component under measurement through one of the plurality of channels;
The impedance measuring device measures an impedance of the electronic component under measurement through the connected channel; And
And the host device displays a graph according to the measurement data of the impedance measuring device. The method of claim 12,
Measuring the impedance is a control method of the impedance measurement system for the host device to automatically correct the time distortion of the impedance measurement data measured by the impedance measuring device. The method of claim 12,
Measuring the impedance is a control method of the impedance measuring system for the host device to automatically correct the DC offset of the impedance measurement data measured by the impedance measuring device. The method of claim 12,
Displaying the graph calculates a design value of a signal line formed on a printed circuit board on which the electronic component under measurement is mounted in accordance with the measurement data. The method of claim 13,
The displaying of the graph is characterized in that the host device adjusts the scale of the graph based on the length of the signal line according to the design value and displays a valid section of the measurement data. .

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