In recent years, driven by surging demand in industrial control systems, new energy vehicles, and renewable power generation sectors, the market for power devices has grown significantly, while performance expectations for these components have become increasingly stringent. As a critical subset of semiconductor devices, power devices are primarily designed to enable high-voltage and high-current power conversion and control, capable of withstanding substantial power loads.

Power devices currently comprise the following primary categories:

• Diodes: Leveraging their unidirectional conductivity, these devices are critical for circuit rectification, voltage regulation, and similar applications.
• Transistors: Key types include Bipolar Junction Transistors (BJTs) and Field-Effect Transistors (FETs), widely employed in amplifiers, audio systems, and power regulators, used for power amplification and switching circuits.
• Thyristors: This family includes Silicon-Controlled Rectifiers (SCRs), Triacs (TRIACs), and Gate Turn-Off Thyristors (GTOs), predominantly used for AC voltage regulation and controlled rectification in power conversion systems.
• MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors): As unipolar devices, MOSFETs are distinguished by fast switching speeds, low driving power, and high input impedance—making them ideal for high-frequency applications such as high-frequency switching power supplies, DC-DC converters, and motor drives requiring rapid switching.
• IGBTs (Insulated-Gate Bipolar Transistors): These devices combine MOSFET and BJT technologies, offering the best of both: high input impedance from MOSFETs, low conduction losses from BJTs, and robust voltage withstand capability. They are widely adopted in high-voltage power electronics applications.
• New-Generation Silicon Carbide (SiC) and Gallium Nitride (GaN) Power Devices: Power devices made from new wide-bandgap semiconductor materials, they exhibit characteristics such as high voltage resistance, low on-resistance, high switching frequency, and high-temperature tolerance. They are widely applied in new energy vehicles, charging piles, solar inverters, industrial power supplies, and other fields. Among these, electric vehicles represent the most critical application scenario for new power devices under the trend of high-voltage fast charging, and the adoption of 800V SiC platforms is also driving the development of SiC power devices.

2 Challenge

As the core method to evaluate the dynamic characteristics of power devices, double pulse test faces multi-dimensional technical challenges in practical applications, which involves not only the complexity of hardware design, but also the precision of test methods and data processing.

2.1 Accuracy requirements of high frequency signal capture

The switching speeds of new wide-bandgap devices (such as SiC and GaN) can reach the nanosecond level, necessitating test equipment with high bandwidth (typically requiring over 500MHz) and low-noise characteristics. For instance, the reverse recovery time of GaN devices can be as short as below 10ns. Insufficient bandwidth can lead to waveform distortion and misjudgment of switching losses. The SDS5000X HD series oscilloscopes from SIGLENT, featuring a 12-bit ADC and 1GHz bandwidth, can accurately capture the test waveforms.

2.2 Technical difficulties of common-mode interference suppression

In high-power testing, the common-mode voltage can reach the kilovolt level, making the common-mode rejection ratio (CMRR) of differential probes a critical parameter. For example, when testing an 800V SiC platform, the CMRR of traditional differential probes may drop below 60dB in the high-frequency band (such as 100MHz), leading to false oscillations in the Vgs waveform. To address this challenge, SIGLENT has launched the ODP6000B series of optical isolated probes. With a CMRR of 160dB and fiber-optic transmission technology, these probes can effectively suppress interference and accurately reproduce the true waveform.

2.3 Intelligent requirements of data processing and analysis

Double-pulse testing requires the synchronized analysis of dozens of parameters, such as switching times (e.g.: tr, tf), energy losses (Eon, Eoff), and voltage/current change rates (dv/dt, di/dt). Manually organizing multiple sets of test data and generating reports consumes a significant amount of time and is prone to data errors and omissions. SIGLENT DPT software, through its built-in algorithms, can automatically identify characteristic of waveforms and generate customized test reports that include waveform screenshots、parameter tables. The report can be exported in HTML or XML formats, improving efficiency by over 80% compared to manual analysis. This function greatly improves the test efficiency and reduces the manual operation error.

3 Solution

3.1 Test Items

The types of switch devices to be tested include MOSFET or IGBT, and the following parameter analyses are supported:

3.2 Test Equipment

The Double Pulse Test is a commonly used test for analyzing the dynamic characteristics of power switching devices such as MOSFETs and IGBTs. Through the Double Pulse Test, the performance of power devices can be conveniently evaluated, and key parameters during both steady-state and dynamic processes can be obtained. This enables a better assessment of device performance and facilitates the optimization of drive design, among other benefits. To perform the Double Pulse Test, the following equipment is required:

3.3 Test Steps

3.3.1 Test connection diagram

For the connection mode of double pulse test, please refer to the following figure：

Test wiring diagram

3.3.2 Generation of double pulse signal

In the Double Pulse Test, two pulses with different pulse widths are required. The first pulse is used to establish the initial state, allowing other components in the circuit to reach a relatively stable operating temperature and reducing the impact of temperature variations on the test results. Simultaneously, it establishes a certain current through the inductor in the circuit, creating conditions for the test with the second pulse. The second pulse is employed to test the dynamic characteristics of the power device. During this phase, an oscilloscope and probes are utilized to measure the voltage and current parameters of the device during switching. The turn-off process of the power device is observed at the falling edge of the first pulse, while the turn-on process is observed at the rising edge of the second pulse.

This special pulse sequence can be edited and generated in software, with the parameters of individual pulse adjusted. The resulting file can then be imported into an arbitrary waveform generator for output. However, this method is rather cumbersome and inconvenient for parameter adjustment. The SIGLENT arbitrary waveform generator has a built-in multi-pulse feature. It displays the characteristics of the output double-pulse waveform intuitively on the signal source interface, and allows for more convenient setting of parameters such as pulse width. The interface is easy to operate with clear guidance, saving engineers’ time and enabling them to focus more on power device testing as well as debugging and resolving issues.

Multi-pulse output setting interface of AWG

In the multi-pulse interface, users can select the number of pulses, and set the relevant rise/fall times and positive/negative pulse widths for each individual pulse. The interface is simple and the operation logic is clear.

3.3.3 Double pulse test software

On the oscilloscope, SIGLENT provides testing software for double pulse test, which can effectively shorten the testing time.

Click Analysis →Double Pulse Test to open a specific test window. According to the test process, it is divided into five steps: Setup, Test Select, configure, Deskew, and Target

3.3.3.1 Setup

• Provides three functions of setting: Recall, Last and Save.
• There are two options to provide DUT Type selection: MOSFET、IGBT.

Window of Setup

3.3.3.2 Test Select

Select the items to be tested in this column.

Window of Test Select

3.3.3.3 Configure

The previously selected test items will be highlighted in this section. By clicking on them, you can configure the corresponding test parameters, such as setting the source for voltage /current measurement, max voltage, etc. The oscilloscope will automatically measure the items according to the settings here. At present, only one-sided switch parameter analysis is supported. Please replace the test wiring as required.

Window of Configure

3.3.3.4 Deskew

A relatively small time delay between voltage and current can lead to significant measurement errors. Deskew Calibration can be performed to correct the time delay of an oscilloscope or probe. When the power device is a MOSFET, calculate the time delay for the Vds voltage channel and the Id current channel. When the power device is an IGBT, calculate the time delay for the Vce voltage channel and the Ic current channel. Deskew can be carried out in conjunction with the DF2001A test board. Refer to the “Switching Loss” section in the power analysis part of the user manual for more detailed information on Deskew Calibration.

Window of Deskew

3.3.3.5 Target

Click Target to enter the page and set the Analysis Target:

l  New Frame: Oscilloscope automatically sets parameters to collect signals according to channel configuration, and then performs analysis.

l  Current Frame: Users manually collect a frame signal according to the channel configuration, and then perform analysis.

Window of Target

3.3.4 Test Result

After clicking Run Analysis, please follow the prompts:

Window of Run Analysis

After the test analysis is completed, click Results to view the test results. The upper part of the test result window is the test items, which provide the test conditions, measured values and pulse region of each item. The lower part has the report setting area and the waveform of the test. Click on the item of interest in the upper part, and the corresponding screenshot will be displayed in the lower part. Click on the picture to enlarge and view the details of the test waveform.

Test Results List

3.3.5 Test Report

Every time an analysis is performed, the test results will be overwritten. If you need to keep the test results, you can save the report. Click Report Config… to edit the test information in the pop-up dialog box. Click Create Report… to select the saving path, and click Preview Report… to view the complete report on the oscilloscope.

The test report includes a summary table of all test results. Click the name of the test item to quickly jump to the details page, which includes a screenshot of related test waveforms.

Note: When saving in HTML format, a folder and an HTML file will be generated. If you need to copy the results, you need to copy them both and keep them in the same path.

Test Report

4 Summary

SIGLENT offers relevant solutions for power device testing, with double – pulse testing being the primary method for measuring the dynamic parameters of power devices, capable of accurately characterizing their related properties. However, constructing the double – pulse signals required for testing and measuring the relevant parameters have long been challenging difficulties for many engineers. SIGLENT arbitrary waveform generator provides a multi-pulse waveform setting interface, offering users a quick and convenient way to edit pulse signals. Meanwhile, the oscilloscope from SIGLENT includes a double – pulse test application, enabling convenient measurement of parameters in double – pulse testing, reducing testing time, and providing intuitive test result reports.

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You can download the VI here: VISA_IDN.ZIP

In this example, the user can:

• Select the connected instruments from the VISA Resource List drop down menu:

NOTE: USB devices will automatically appear. For LAN connections, you will need to add the device. This is commonly done using NI Measurement and Automation Explorer (NI-MAX)

• Request the identification string once-per-press of the RUN button.

This sends the “*IDN?” identification query string to the instrument. The instrument then responds to the query with its identification string information. The identification string data will appear in the text box.

This code also uses the event structure connected to the value change of the RUN button to run once-and-only-once per keypress. This is a useful method of controlling code execution.

• Stop and exit upon pressing the STOP button

To run:

1. Connect instruments using a USB or LAN connection (see users manual for specific instrument details)
2. Power on instrument
3. Open LabVIEW and select the IDN.VI. This will open the VI front panel:

4. Select the instrument of interest from the VISA Resource drop down menu:

5. Press RUN on the LabVIEW VI menu strip to run the program:

6. Now, the “graph paper” background goes clear, indicating that the code is running. Now, you can press RUN in the VI Front Panel to execute the code:

The identification string should appear in the textbox:

7. Press STOP on the VI Front Panel to exit the code

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The VXI bus and subsequent software drivers form a convenient software API that can make remote control of instrumentation over LAN quite simple. In fact, it forms the basis of the TCPIP communications used in LXI format that is being implemented across the industry.

For more info on VXI, you can check out the VXI Consortium

VXI has a small installation size and is quite flexible.. especially when compared to VISA based applications. VISA is convenient and does allow for easy bus changes (from GPIB to USB with just a few lines of code), but it is also a large installation that isn’t always easy to use on machines that are not running Windows.

VXI has many flavors.. and can be used with many OS’ and can be used on many instruments that do not have “open sockets” on their LAN connection.

Here is a list of SIGLENT products that have LAN but do not have open sockets:

SDS2000

SDS2000X

SDS1000X/X+

SPD3000X/XE

In this note, we are going to show how to use VXI-11 with Python to control an instrument. This can be used with traditional OS’ like Windows but offer even more when coupled with Linux variants like those running on Rasberry Pis and other single board computers (SBCs).

Configuration

First, you will need to download a few programs..

• Python: https://www.python.org/downloads/release/python-2714/

NOTE: This technique works with version 2.x and 3.x.. in this example, we will use Python 2.7.14 for Windows 64 bit OS’

• Python VXI-11: https://github.com/alexforencich/python-vxi11

Once downloaded, you can add VXI-11 to your Python instance..

1. Open the command line program in Windows. You can find it by searching for “CMD” or by going to the Start Menu >  Windows System > Command Prompt as shown here:

2. In another window, find the location of the Python VXI-11 folder that was downloaded previously and find the path for setup.py. In this case, the path on my PC is shown as:

Now, you can click on the “address” to open the exact path:

Here, I suggest opening Notepad and “copy-paste” the path. It will make the transfer easier:

3. Change the directory in the Command line program to match the path from step 2:

Type “cd <PATH>” as shown:

4. Now, the directory has changed to match the path. You can run the setup.py file by typing “python setup.py install” as shown:

5. Close the Command Prompt

Test the installation

Now that everything has been installed, let’s test the communications link.

1. Connect the instrument to the LAN of the controlling computer and power it on

2. Check the IP address for the product (see the User’s Guide of the specific product for more info), In this case, I am using an SDS2000X oscilloscope. Here is the IP address information:

3. Now, start the Python shell. There are a few ways to start this application. In this case, you can find the Python folder in the Windows start folder.

Open IDLE (A Python GUI):

Now, click Run > Python Shell to open the shell:

4. Now, import the VXI11 library by typing “import vxi11”

5. Now, we can assign the variable “instr” to the instrument as shown:

6. Now, we can use the VXI Ask command to send the identification string (*IDN?), request the response, and print it to the screen:

The VXI11 library features a number of functions to handle writing and reading strings and other formats. You can use this technique to establish communications and control the instrument efficiently.

Click here to download a Python file of this example: PythonVXI11_IDN

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This example scans and lists the available resources.

It requires PyVISA to be installed (see the PyVISA documentation for more information)

***

#Example that scans a computer for connected instruments that
#are compatible with the VISA communication protocol.
#
#The instrument VISA resource ID for each compatible instrument
#is then listed.
#
#
#Dependencies:
#Python 3.4 32 bit
#PyVisa 1.7
#
#Rev 1: 08302018 JC

import visa

def main():
    rm = visa.ResourceManager()
    print (rm.list_resources())

if __name__=='__main__':
    main()

*****

Here is the code:

And here is the result of a scan:

Each connected instrument returns a specific formatted string of characters called the VISA Resource ID.

The resource ID format is as follows:

‘Communication/Board Type (USB, GPIB, etc.)::Resource Information (Vendor ID, Product ID, Serial Number, IP address, etc..)::Resource Type’

In the response, each resource is separated by a comma. So, we have three resources listed in this example:

‘USB0::0x0483::0x7540::SPD3XGB4150080::INSTR’ – This is a power supply (SPD3X) connected via USB (USB0)

‘USB0::0xF4EC::0x1301::SVA1XEAX2R0073::INSTR’ – This is a vector network analyzer (SVA1X) connected via USB (USB0)

‘TCPIP0::192.168.55.122::inst0::INSTR’ – This is an instrument connected via LAN using a TCPIP connection at IP address 192.168.55.122

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Luckily, there are a few solutions that can help. In this application note, we are going to discuss using open socket communication techniques using an open source communication tool called PuTTY with a SIGLENT SSA3032X Spectrum Analyzer.

What are open sockets and why use them?

Within the context of Ethernet/LAN connections, sockets are like mailboxes. If you want to deliver information to a specific place, you need to be sure that your information is delivered to the correct address.

In the context of test instrumentation, an open socket is a fixed address (or port number) on the Ethernet/LAN bus that is dedicated to process remote commands.

Open sockets allow remote computers to simply use existing raw Ethernet connections for communications without having to add additional libraries (VISA or similar) that require additional storage space and processing overhead.

Programs that utilize sockets for LAN communication tend to take up less memory and operate more quickly.

PuTTY

PuTTY is an open source software tool that provides a number of simple communication links (RAW, Telnet, SSSH, Serial, and others). It is available for free and there are a number of versions available for popular operating systems.

You can download as well as learn more here: http://www.putty.org/

In this example, we are using PuTTY to verify the raw LAN connection is working properly. It is quite a simple program that does not allow for very complex operation (sequences, converting data sets/strings, etc..). If you require more complex functionality, software platforms like Python, .NET, C#, LabVIEW, etc.. can be used to control the instrument using a similar open socket connection.

Configuration

In this test, we are using the most current revision of the SIGLENT SSA3032X Spectrum Analyzer firmware (Revision 01.02.08.02) which enables open socket communication.

This example also uses PuTTY version 0.67:

Steps

1. Install PuTTY for the OS you intend to use

2. Make sure your instrument and firmware revision can use open sockets

The SSA3032X revision 01.02.08.02 enables open socket communication.

To find the revision, press the System button > Sys Info.

Figure 1 below shows a sample system information screen from a SIGLENT SSA3000X analyzer:

Check the product page and firmware release notes for more information.

3. Connect the instrument to the local area using an Ethernet cable

4. Find the IP address for the instrument. This is typically located in the System Information menu. On the SIGLENT SSA3032X, press the System button on the front panel > Interface > LAN.

Figure 2 below shows a sample LAN setup page from a SIGLENT SSA3000X:

5. Open PuTTY

6. Select Raw as connection type

7. Enter the IP address in the Host Name field

8. Enter the port number. This should be provided in the users or programming guide for the instrument.

The SIGLENT SSA3000X Spectrum Analyzer uses port 5025.

Figure 3 below shows the PuTTY configuration for this example:

9. Press Open. This will open a terminal window as shown in below:

10. Using the computer keypad, enter *IDN? and press the Enter key on the keyboard to send the command.

This is the standard command string that is used to request the identification string from the instrument. As shown below, the instrument responds with the manufacture, product ID, Serial Number, and firmware revision.

Conclusion

PuTTY is an easy way to verify an operational LAN connection to instrumentation that can use open sockets.

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This process normally goes quite smoothly, but if there are problems, there are some basic troubleshooting steps that can help get your test up-and-running quickly.

In this note, we are going to show how to use NI-MAX to test the communications connection between an instrument and a remote computer using both a USB and a LAN connection to ensure that they are working properly. Once the connection is verified, you can begin to work on the control software.

National Instruments Measurement and Automation Explorer (NI-MAX) is a free communications tool provided with NI’s VISA library.

You can learn more here: http://digital.ni.com/public.nsf/allkb/71544521BDE34FFB86256FCF005F4FB6

USB Connections

1. Power on and connect the instrument via USB cable to the computer. On a computer running Windows, the first time you connect the USB from an instrument should open a dialog box or show a notification of a new device being connected.

You can check the status of the USB connections by opening Device Manager located in the Control Panel menu of most Windows Operating systems and expanding the driver information as shown below in this Windows 10 example:

This indicates that the operating system recognizes the connected instrument as a test instrument.

If the device manager reports the USB connection as some other type of device (printer, camera, unknown, etc.), there is likely a problem linking the proper driver (ausbtmc.sys) to the instrument. One possible solution to this is to disable the driver, disconnect the USB cable, verify that ausbtmc.sys exists, and then reconnect the USB cable.

2. Run NI-MAX by left-clicking on the icon on the desktop or finding it via the start menu

3. This will open the main window, as shown below:

4. Expand the “Devices and Interfaces” menu. You should see the instruments attached via USB with a brief description as shown for an SDS2000X oscilloscope below:

This indicates that a software application (NI-MAX) has correctly identified a test and measurement device (the oscilloscope) over the USB connection.

5. By left-clicking on the instrument, you can see additional information about it:

6. To further test the connection, right-click on the instrument and select Open VISA Test Panel or select it from the side bar:

The VISA Test Panel window shows some helpful information, including the instrument manufacturer, model, serial number, and the USB identifier (VISA Address) along the top.

7. Another useful item in the VISA Test Panel is the Input/Output function. This mode allows you to send specific instrument commands and receive instrument responses.

This is especially helpful when you are planning a specific test sequence, the effect of delays/timing, or troubleshooting a command. You can send each
command one-at-a-time and check the performance of the instrument.

Select Input/Output > Basic I/O > and Enter the command in the text window:

– *IDN? is a common identification string query (question or information request) that returns the information from the connected instrument
– /n is a termination character that represents a new line. This is the standard termination character for SIGLENT instrumentation.
– Write will send the command to the instrument
– Read will pull data from the instrument
– Query will perform a read and then a write command to request and return data from the instrument

USB Checklist

– Is the USB port configured properly on the instrument? Some instruments feature USB ports that can be configured as TMC (Test and Measurement) or Printer communication ports. The USB port should be set to USBTMC or similar for remote control.
– Try a direct connection to the controlling computer. USB hubs or long connections may cause issues.
– Try a different USB cable. Connectors can go bad or prove to be faulty.
– Try a different USB port on the computer.
– On machines running Windows, check the Device Manager. Test instrumentation should appear as USB Test and Measurement Device (IVI) and use the AUSBTMC.SYS driver

Lan Connections

1. Power on and connect the instrument via LAN cable to a LAN network connected to the computer you wish to use.

You can check the status of the LAN connection by using a software tool like NMAP: https://nmap.org/

NMAP allows you to scan networks and identify IP addresses.

First, identify the LAN connection for the instrument. This is typically located in the System menu under IO or LAN settings.

Here is the IO information for an SDS2000X oscilloscope:

DHCP Enabled will automatically configure the instrument connection settings and apply a valid IP address. With DHCP enabled, the IP address may change over time. It is recommended to check the instrument IP address and then confirm that it is visible on the network using NMAP:

Here, we are performing a Ping (short scan to identify what IP addresses are being used) over the range of IP addresses that may match the instrument.

This can be performed by setting the target using the “/24” extension. This scans 24 bits For example, 192.168.10.0/24 would scan the 256 hosts between
192.168.10.0 and 192.168.10.255

Here is more information from NMAP:
https://nmap.org/book/man-target-specification.html

For example, to ping all IP addresses that start with 192.168.0., set the target as follows:

Note the IP address and MAC address that identify your instrument.

2. Run NI-MAX by left-clicking on the icon on the desktop or finding it via the start menu

This will open the main window, as shown below:

3. Unlike USB, there is not an easy way to identify all of the instruments connected via LAN.

In many cases, you will have to manually add the LAN instrumentation. Recall from Step 2, our instrument IP address is 192.168.0.87

Right-click on Network Devices, and select Create New VISA TCP/IP Resource:

4. Select Manual Entry of LAN:

5. Enter the IP address and press Validate

6. After successfully creating a TCP/IP connection, select finish

7. After the system updates it’s configuration, the instrument will appear in the Network Devices menu:

8. To further test the connection, right-click on the instrument and select Open VISA Test Panel or select it from the side bar:

The VISA Test Panel window shows some helpful information, including the TCP/IP identifier (VISA Address) along the top.

9. Another useful item in the VISA Test Panel is the Input/Output function. This mode allows you to send specific instrument commands and receive instrument responses.

This is especially helpful when you are planning a specific test sequence, the effect of delays/timing, or troubleshooting a command. You can send each command one-at-a-time and check the performance of the instrument.

Select Input/Output > Basic I/O > and Enter the command in the text window:

– *IDN? is a common identification string query (question or information request) that returns the information from the connected instrument
– /n is a termination character that represents a new line. This is the standard termination character for SIGLENT instrumentation.
– Write will send the command to the instrument
– Read will pull data from the instrument
– Query will perform a read and then a write command to request and return data from the instrument

For more information, check SiglentAmerica.com, or contact your local Siglent office.

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