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.

The post Double Pulse Testing Solution appeared first on Siglent.

Multi-channel function generators are useful in many situations. For example, in some testing the generator needs to output several phase-coherent signals and for the phase to be independently adjustable for each signal. In 3-phase power line harmonic distortion testing, a 4 channel generator is required to simulate the multiple voltages and currents.

1.1 Problem

A standalone multi-channel generator can be very expensive.

1.2 Solution

Siglent provides the Multi-Device Synchronization function in the SDG2000X and SDG6000X generators. This allows synchronization among several units in order to output signals with adjustable steady phase relationships. Thus saving on cost.

2. Setup of Synchronization

2.1 Wiring

Multi-Device Synchronization will require the use of the Aux In/Out and 10 MHz In/Out rear-panel interfaces to implement the synchronization. First, all the generators’ Aux In/Out BNC connectors need to be connected together. Next, connect the Master unit’s 10 MHz Out to the Slave unit’s 10 MHz In. Please note that the SDG6000X family has separate 10 MHz In/Out outputs, so more than two units can be synchronized. The wiring interconnection concept is shown in Figure 1.

Figure 1. Wiring concept

However, the SDG2000X  series’ 10 MHz In/Out ports shares one connector.  Therefore, only two units can be synchronized together or they must be the last Slave unit in a multiple units connection.

In this note, the SDG2000X and SDG6000X series models are used as our example. The SDG6000X will be the Master device.

1) First connect two units’ Aux In/Out with BNC cable. See in Figure 2.

Figure 2. Connect SDG2000X and SDG6000X Aux In/Out

2) Next connect the SDG6000X 10 MHz Out port with the SDG2000X 10 MHz In/Out port, as shown in Figure 3.

Figure 3. Connect Master 10 MHz Out to Slave 10 MHz In

2.2 Parameter settings

Set the waveform parameters, such as Frequency and Amplitude, on 4 all channels. More information on this step can found in the User Manual.

Press Utility, go to Page 2/3, choose Phase Mode, and then set both units as Phase Locked.

In this example we are setting all 4 channels as a 1 kHz, 4 Vpp square wave. CH3, CH4 signals viewed on the SDS5000X oscilloscope are output by the Slave generator, note that the phase is drifting. Open the Display/ Persist function to track it on the scope, as shown in Figure 4.

Figure 4. Four signals phase drift without synchronization

 2.2.1 Set Master Device

1) Press Utility, go to Page 3/3, then press the soft key under screen to select Multi-Device Sync. The menu will enter the Multi-Device Synchronization screen, shown in Figure 5.

Figure 5.  Multi-Device Synchronization Screen

2) Press the soft key under the screen to turn on/off this function and select it as either the Master or Slave. The Multi-Devices Synchronization menu will appear when turned on. When ”Master” appears shaded in light gray this means the device is designated as the Master device, as shown in Figure 6. When this device is set to be the master, its clock source is automatically set to internal and the 10 MHz output is enabled.

Figure 6. Turn on synchronization function

2.2.2 Set Slave Device

1) Enter into the Multi-Device Synchronization menu. Select it as Slave, Slave will be shaded in blue, as in Figure 7. As the device is set to a slave device its clock source is automatically set to external.

Figure 7. Select the unit as the Slave device

2) Turn on the State. Then the Slave Device Delay window will occur. Press to enter delay value, as shown in Figure 8.

Figure 8. Set the Slave Delay

2.2.3 Synchronize the Devices

Press the soft key ”Syncs Devices” in the Multi-Device Synchronization interface of the Master device, as shown in Figure 1, to begin synchronization between the master and slave devices. Anytime a setting is changed; for example, the Slave Device Delay, ”Sync Devices” must be pressed to activate the new settings.

3. Measure on an Oscilloscope

3.1 Slave Device Delay measurement

1) Turn on Synchronization on both units, measure the Skew between CH1 and CH3. As in Figure 9.

Figure 9. Measure the Skew between Master and Slave Devices

2) Enter the absolute Mean value of Skew into Slave Device Delay. This will eliminate the delay between traces that we observed with our oscilloscope. See Figure 10.

Figure 10. Eliminate the Slave Delay

3.2 Adjust phase relationship

Set CH1 Phase as 0 degrees, CH2, CH3, CH4 Phase as 180, 270, 360 degrees, respectively. The result is shown in Figure 11.

Figure 11. Adjust phase relationship

The post Multi generator synchronization appeared first on Siglent.

Sockets via LAN can be helpful if you wish or are unable to use the VISA library.

Here is a picture of the data once it has been loaded into the SDG:

Here is a picture of the generator output on the controlling computer:

Here is the generator output on an oscilloscope:

You can download the Python .py script here:
SDG Python Socket Demo

import socket
import sys
import time
import binascii

remote_ip = "192.168.1.84"
port = 5025
count = 0

wave_points = [0x8000, 0x3f06]

for i in range (1000):
    wave_points = wave_points + [0x8000, 0x3f06]

def SocketConnect():
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    except socket.error:
        print('Fail to creat socket.')
        sys.exet();
    try:
        s.connect((remote_ip, port))
    except socket.error:
        print('failed to connect to ip' + remote_ip)
    return s

def SocketQuery(Sock, cmd):
    try:
        Sock.sendall(cmd)
        time.sleep(1)
    except socket.error:
        print('Send failed')
        sys.exit()
    reply = Sock.recv(4096)
    return reply

def SocketSend(Sock, cmd):
    try:
        cmd = cmd + '\n'
        Sock.sendall(cmd.encode('latin1'))
        time.sleep(1)
    except socket.error:
        print('Send failed.')
        sys.exit()

def SocketClose(Sock):
    Sock.close()
    time.sleep(.300)

def create_wave_file():
    f = open('wave1.bin','wb')
    for a in wave_points:
        b = hex(a)
        b = b[2:]
        len_b = len(b)
        if(0 == len_b):
            b = '0000'
        elif(1 == len_b):
            b = '000' + b
        elif(2 == len_b):
            b = '00' + b
        elif(3 == len_b):
            b = '0' + b
        c = binascii.a2b_hex(b)
        f.write(c)
    f.close()


def main():
    global remote_ip
    global port
    global count

    create_wave_file()
    s = SocketConnect()
    
    f = open('wave1.bin', 'rb')
    data = f.read().decode('latin1')
    data1 = data.encode('latin1')
    with open('wave2.bin', 'wb') as f1:
        f1.write(data1)
    
    print('write bytes:', len(data))
    
    data = str(data)
    
    SocketSend(s,"C1:WVDT WVNM,wave1,FREQ,2000.0,AMPL,3.0,OFST,0.0,PHASE,0.0,WAVEDATA,%s"%(data))
    SocketSend(s,'C1:ARWV NAME,wave1')
    f.close()
    SocketClose(s)
    print('Exit.')

if __name__ == '__main__':
    proc = main()

The post Programming Example: SDG waveform creation with Python and Sockets (no VISA) appeared first on Siglent.

Generate a stereo-FM multiplex waveform with Python and AWG

The post Baltic Labs: Generate a stereo-FM multiplex waveform with Python and AWG appeared first on Siglent.

The majority of modern arbitrary/function waveform generators utilize DDS technology (Direct Digital Synthesis), but there are a few obvious defects using this technology directly. To solve these disadvantages, SIGLENT invented a pulse generating algorithm called EasyPulse technology. In this note, we will describe the basics of DDS and how EasyPulse can help get the best performance possible.

1.DDS technology and its disadvantages

Direct digital synthesis (DDS) is a technique to produce an analog waveform (square, triangular, or sinusoidal) by generating a digital time-varying signal in digital form and then performing a digital-to-analog conversion. A basic Direct Digital Synthesizer consists of a frequency reference (often a crystal or oscillator), a numerically controlled oscillator (NCO) and a digital-to-analog converter (DAC), the block diagram is shown in Figure 1.

The reference clock is a fixed frequency (F_ref). DDS generates the waveform by looking up the pre-loaded 2^N data samples from memory.

The Tuning word (M) stored in the register determines the frequency of the output:

Since the edges of square/pulse signals output through the DDS technology are fixed, and the duty-cycle is limited by the data length, there will be poor duty-cycle setpoint resolution at higher output frequencies.

When generating a square/pulse, the reference frequency should be an exact integral multiple of the output frequency. If it is not an exact integral multiple, it will introduce a deterministic jitter equal to one reference clock period.

When the Tuning word ＞1  (i.e. F_out ＞F_ref /2^N ), some points in the sample lookup table are skipped. This is generally not a big problem for sinusoidal waveforms, but for arbitrary waveforms with some important details (e.g. spikes), it may mean the loss of information.

2.EasyPulse technology and its benefits

To solve these problems, Siglent invented a pulse generating algorithm called EasyPulse, which is applied to all of the SDG X series waveform generators.

Based on this new technology, the SDG series waveform generator is capable of generating a pulse signal with low jitter, rapid rising and falling edge (independent from frequency), small duty cycle( pulse width), edge and pulse width can be adjusted in a wide range. Figure 3 is the block diagram of EasyPulse:

Take the SDG6052X series Pulse/Arbitrary Waveform Generator as an example, its specification for a pulse signal are as follows:

3.Measurement examples

Equipped with the EasyPulse technology, the SDS6052X series Pulse/Arbitrary Waveform Generator delivers great performance. Let’s take a look at some real-world examples:

First and foremost, the EasyPulse technology could overcomes the additional jitter in Square/Pulse waveform generated by traditional DDS. To evaluate this excellent feature, we compared a DDS waveform generator with the SDG6052X with EasyPulse. In figure 4, we used a 12-bit scope to observe the differences. When the Pulse is trigged, measuring the next rise edge, we observe a 0.84 ns (which is equal to the period of the DDS clock, 1.2 GHz) peak-peak jitter if the pulse is generated by traditional DDS, while the jitter downs to 11.2 ps rms when we choose EasyPulse technology to generate the pulse with same configuration.

Another advantage of the EasyPulse technology is its ability to output the pulse with a small pulse width around 3.3 ns, even at very low frequency. For a 1 Hz pulse generated by DDS technology, there are 32768 points in one waveform length. If we built the pulse with only one sample point at the high level, we could get a pulse with the minimum pulse width (minimum duty ratio as well), which is about 30 ms (1 s/32768 ≈ 30.5 ms), as shown in figure 6. With EasyPulse, the width can be adjusted down to 3.3 ns as shown in figure 7.

In addition, with the EasyPulse technology, both the edge and pulse width can be adjusted over a wide range. The pulse width can be fine-tuned to the minimum of 3.3 ns with an adjustment step as small as 100 ps, at any frequency. In figures 8 and 9, we used a 12-bit scope with infinite persistence to show the rising edge changes with pulse width settings from 3.4 ns to 200 ns with 100 ps each step.

The rise/fall times can also be set independently to the minimum of 1 ns at any frequency with a minimum adjustment step as small as 100 ps. Output an initial pulse by the SDG6052X as the following parameters:

Figure 9 shows the rising edges of the SDG6052X Pulse/Arbitrary Waveform Generators from 1.0 ns to 100.0 ns step by step with 100 ps.

In conclusion, EasyPulse technology enables SIGLENT Pulse/Arbitrary Waveform Generators to perform excellently when generating a pulse signal with low jitter, small duty cycle, precise and adjustable pulse width.

The post EasyPulse Technology and Its Benefits appeared first on Siglent.

The waveform data can be sent as individual samples formatted as binary little-endian, 2s complement values.

In this programming example, we create a 10 point arbitrary waveform that starts at the least-significant bit and steps up to the most-significant bit to help with understanding the required sample format as well as provide a base for your own waveform creation.

Here is a picture of the desired waveform:

The SDG waveform data requires each sample to first be formatted as binary, little-endian, 2’s complement. For easier human viewing, the example enters the data in hex format and then “unhexes” the data before it is added to the command string which is then sent to the instrument.

Here is a table showing the value of each sample and the value in hex for 14-bit (SDG1000X series) and 16-bit (SDG2000X/SDG6000X) instruments:

Here is an oscilloscope capture of a single burst of this waveform:

MATLAB Example

Here is a MATLAB SDG Stair Step Example

The post Programming Example: Create a stair-step waveform using MATLab (SDG1000X, SDG2000X, SDG6000X) appeared first on Siglent.

Arbitrary waveform generators can easily replace the function generators. They can source sine waves, square waves, and triangle waves like a standard function generator. In addition, they can also output pulse, noise, DC signal types, modulated signals, sweeps and bursts. Many arbitrary waveform generators currently on the market are equipped with arbitrary waveform drawing software. Through this software, theoretically, the arbitrary waveform generator can be remotely controlled to output all the signals required in the test process.

So, what types of waveforms can an arbitrary waveform generator output?

What parameters are available for an arbitrary waveform?

How to measure the quality of the output waveform?

1. Sine Wave / Cosine Wave

Figure 1 Sine wave / Cosine wave

Sinusoidal (sine) and cosine waves are the two most familiar waveforms in electronics.

Sine/cosine waves are defined as follows.

 (Formula 1)

OR

(Formula 2)

Where A represents the amplitude of the sine wave,  represents the angular frequency, and  represents the initial phase, which can be omitted in the general calculation. The sine and the cosine waves are essentially the same, but the initial phase differs by 90 °.

Figure 2 Sine wave setting interface in SDG1000X

These three parameters are as shown in Figure 2. The frequency and period related to the angular frequency can be set in the arbitrary waveform generator, and the conversion relationship between them is:

(Formula 3)

The frequency of a generator, like the SIGLENT SDG2122X function / arbitrary waveform generator sine wave can be set up to 120 MHz. Usually, the nominal maximum output frequency of the arbitrary waveform generator often refers to the maximum frequency of its sine wave output.

You can also set the amplitude, A. When the output impedance is set to the “high impedance” state, the maximum output amplitude of the SDG2122X can reach 20 Vpp.

The initial phase can be set by clicking the corresponding button in the [Phase] menu. The range of the initial phase can be set between -360 ° and + 360 °.

From the time domain perspective, the parameters and waveforms of the sine and cosine waves are relatively simple. However, all electronic devices have more or less distortion, and arbitrary waveform generators are no exception. Let’s observe sine and cosine waves in the frequency domain.

The Fourier transform corresponding to the time domain function represented by Formula 1 is:

 (Formula 4)

The spectrum diagram represented by Formula 4 is shown in the figure below:

Figure 3: Cosine spectrum/frequency domain

Looking at the cosine spectrogram (showing amplitude vs. frequency) in Figure 3, we can find that the frequency of a sine/cosine wave can be represented by a single line on the spectrum. Signals that occupy only one frequency are called “monotone” because they only have one frequency component.

In engineering, due to the non-ideal characteristics such as the non-linearity of the circuit, the generated sine wave is often not an ideal monotone signal, but may contain other frequencies. Collective “unwanted” frequencies are often lumped together under the term distortion. Some common contributors to distortion are harmonics and spurs.

• Harmonic distortion

The fundamental frequency of a signal is the lowest frequency component of a periodic signal. Harmonics are the frequency components of the signal that are integer multiples of the fundamental. Distortion is the ratio of signal power to maximum harmonic power, usually in dB, as shown in the following figure:

Figure 4: Harmonic distortion

Another index to measure the performance of harmonic distortion is total harmonic distortion (THD), which refers to the ratio of the root mean square of the amplitude of each harmonic (usually taken to the 6th harmonic in engineering) to the signal amplitude, as shown in Formula 5, usually expressed in %. When an SDG2000X outputs 0 dBm, 10 Hz ~ 20 kHz sine wave, the total harmonic distortion is 0.075% at most.

(Formula 5)

• Non-harmonic spurs

In addition to harmonics, the distortion caused by nonlinearity may also be some other spectral components, such as the intermodulation products of the signal (or its harmonics) and the clock signal. It is necessary to define other index-non-harmonic spurs to measure.

The size of the spur is usually expressed by the spurious-free dynamic range (SFDR) (see Figure 5), which refers to the ratio of the signal power to the maximum spurious power. The unit is usually dB. Please note that the definition of spurs in some places includes harmonic and non-harmonic spurs, but in arbitrary waveform generators, spurs only refer to distortions other than harmonics.

Figure 5: SFDR

For More information, please click here.

The post The basic output waveform and related parameters of the arbitrary waveform generator appeared first on Siglent.

In this series of notes, we are going to introduce some of the features that make AWGs so useful and explain in a bit more detail just how they work.

What types of signal sources are on the market today?

Let’s start with the basics. Most sources can be divided into two broad application categories: Digital and Analog.

Signal sources specially created for digital applications are often called logic sources. Logic sources can be roughly divided into two categories: Pulse and pattern generators. A pulse generator can output square waves and pulse streams. The output frequency of the pulse generator is generally very high and it is often used to test digital devices. A pattern generator, also known as a logic source or data generator is a bit unique.  This kind of instrument generally has 8 or 16 output channels, but higher channel counts are available. Each output can generate various types of synchronous digital pulse streams, generally from a low to a high voltage value, 0-5 V for example. Pattern generators are often used as excitation signals for computer buses, digital telecommunications units, and other serial communications links.

Analog generators typically have one or two outputs and feature a wider array of possible output levels, wave shapes, and frequencies than digital sources. More specialized forms of analog generators also exist for high frequency applications. We aren’t going in to further detail about them here, but some common types include RF signal generators, microwave signal generators, and baseband signal generators.

In this article, we will concentrate on the most general purpose signal source, the arbitrary waveform generator. In simple terms, an arbitrary waveform generator is a device that creates an output signal based on a digital waveform file, created from a series of discrete output sample points, and “plays” the file contents at the source output of the generator. Using this sampling principle, waveforms of almost any type can be created, including basic waveform functions like square, sine, and ramping output shapes.

Arbitrary waveform generators can also have more advanced functions like output triggering and system clock signals for synchronizing external instruments. One such generator is the SIGLENT SDG2000X series function / arbitrary waveform generator shown in Figure 1 below.

Figure 1: SIGLENT SDG2000X function / arbitrary waveform generator

What is the waveform generator used for?

As mentioned previously, most arbitrary waveform generators include basic function types like sine, square, and triangle waves. In addition, waveform generators can also generate analog and digital modulation signals, supporting the output of linear / logarithmic sweep signals and pulse trains. Many of SIGLENTs SDG series of generators  support AM, FM, PM, FSK, ASK, DSB-AM and other analog and digital modulation functions and include a large standard library of included arbitrary waveform functions.

There are hundreds of applications for waveform generators, but in the field of electronic test and measurement, the application range can be basically divided into three types: inspection, verification, and limit / margin test. During the commissioning phase of a design, the engineer needs to test the parameters of the product to verify whether the product meets the relevant design specifications. In this process, the waveform generator can be used to source the signal specified in the design specification. Here, the Engineer can observe the response of the design, compare the results with the specifications, and perform any adjustments that may be necessary with the design. In addition, newly developed industrial control modules, data conditioning modules, and others all need to use waveform generators to test their linearity and monotonicity through exhaustive testing. In many occasions, the waveform source needs to add a known, repeatable distortion in quantity and type to the signal it provides. With many generators, you can add noise and programmed distortion to the signal and directly test the ability of the design to handle specific real-world signal issues.

What are the main indicators of the waveform generator? What do these indicators mean?

Oscilloscopes have common banner specifications: Bandwidth, memory depth, and sampling rate. When we select a suitable oscilloscope, these three major indicators are often our first consideration.

Does the waveform generator also have the so-called three major indicators? The answer is yes. In the category of waveform generators, there are also concepts of bandwidth, sampling rate and memory depth.

1. Bandwidth

The bandwidth of the waveform generator is often defined as the maximum frequency of a sine wave. Unfortunately, what applies for a sine wave may not apply to other waveform types. For example, the maximum sine wave output frequency of the SIGLENT SDG2122X is 120 MHz, while the square wave has a maximum frequency of 25 MHz. The reason for this difference is that a square waveform transitions very quickly from one voltage value to another. Faster transitions require that the waveform contains many higher-frequency components than the smooth transitioning sine wave. In order to avoid heavy distortion of the rising edge of the square wave output, when the waveform generator outputs a square wave, its bandwidth range must be able to include these higher harmonic components.

2. Sampling rate

The sampling rate of the waveform generator is usually expressed in mega-samples (MSa/s) or giga-samples per second (GSa/s). For example, the nominal sampling rate of SDG2000X series function / arbitrary waveform generator is 1.2 GSa / s. This parameter indicates the output rate of each sample of the waveform being sourced. The Nyquist sampling theorem stipulates that the sampling rate or clock rate must be at least twice the highest spectral component of the generated signal, thus, accurate reproduction of the original signal can be guaranteed. But in practical applications, twice is often not enough, depending on the type of signal and the rise time. Higher output sampling rates indicate that a signal source is capable of sourcing samples quickly. Low sample rates can limit a generators ability to accurately source a given waveform type.

Here is a quick example.

If you have a waveform made of 1,000 samples and your generator can source 10 MSa/s, the maximum output frequency of the waveform can be calculated as follows:

Frequency = Sample Rate/Samples = 10 MSa/s / 1000 Samples = 10 kHz.

So, the sample rate and number of samples used to create your waveform determine the output waveform period and can be a quick test to determine if the generator will work for your application.

3. Memory depth

Memory depth refers to the number of data points used to record the waveform, which determines the maximum number of samples of the waveform data. The bandwidth of the waveform generator is determined by the sampling rate and memory depth. The SDG2000X series function / arbitrary waveform generator supports “point-by-point output”, which can output 8 pts ~ 8 Mpts at a variable sampling rate of 1 uSa / s ~ 75 MSa / s without losing waveform details. Deeper memory provides higher resolution in the time domain and enables users to create more detailed waveforms.

In addition to the above three indicators, frequency resolution and vertical resolution are also important indicators of waveform generators. Vertical resolution refers to the smallest voltage increment that can be programmed in the waveform generator, and is related to the number of DAC bits used in the hardware circuit. It is generally expressed in units of “bits”, which determines the amplitude accuracy of the output waveform. Frequency resolution, the smallest adjustable frequency resolution, that is, the smallest time increment that can be used when creating a waveform, is related to the highest rate of the clock and the conversion rate of the DAC.

The waveform generator is one of the most widely used basic general-purpose instruments and it is an indispensable tool for simulating signals and testing your design performance. For more information, search out our additional articles to give you more understanding of the principles of the waveform generator.

The post AWG Basics-1 appeared first on Siglent.

IMD is an important test for verification of audio amplifiers and radio receivers as high IMD can cause audible distortion that can decrease the quality of the transmission.

In this experiment, AA7U and N4CY use a SIGLENT SDG2042X generator to deliver the IMD tones and a SIGLENT SSA3X spectrum analyzer to measure the result.

They also build some filtering to help decrease the harmonic content of the generator and build a coupler with better performance than commercially available products.

***

Siglent SDG2042X (AWG) Dual Channel Arbitrary Waveform Generator set up for use in IMD Test Set

1. Turn on the AWG (arbitrary waveform generator) — wait for it to initialize.
2. Frequency is highlighted, with 1 kHz the default. Enter “3”, then touch “MHz” at the bottom left. (By touching the screen where it says Frequency, you can enter the frequency on the keypad “3” then at the bottom of the screen touch “MHz” and that will set the frequency).
3. You will need to be set to 3 MHz (3.007 MHz) on Channel 1 and set 4 MHz (4.011 MHz) on channel 2 (Note: The reason for using the odd frequencies is the Siglent SSA3021X (SA.. or Spectrum Analyzer) has a sub-harmonic spur at 5 MHz)
4. Load–HI Z is the default. Select “50 Ω” at the bottom, by touching the screen.
5. Amplitude–2.00 Vpp is the default when in 50 ohms load. Enter “0”, then touch “dBm” on the bottom (fifth one over from the left–Vpp; mVpp; Vrms; mVrms; dBm). Make sure to set dBm.
6. Output–OFF is the default. Touch it and it turns ON and the Ch1 indicator turns on with the button also, by its BNC connector.
7. Repeat the above for Ch 2 as described above.
8. Adjust Amplitude settings for each channel, which are going through the Band Pass Filter (BPF), 3 dB attenuator, combiner and DUT under test for a 0 dBm on the SA, with the SA internal Attenuator set at -20 dB.

(Note: As an example, this will be around (~ -10dBm). Make sure that the 3 MHz BPF is connected to the 3.004 MHz Channel and the 4 MHz BPF is connected to the 4.011 MHz Channel.

IMD Test Setup–Spectrum Analyzer setup for Siglent SSA 3021X

There are two parts to the setup–the first part sets the levels at the DUT output to 0 dBm; the second part measures the IMD.

Part 1

(Calibration) Push “Preset”, Top Right, to set up for initial setup.

Set Center Freq 3.5 MHz, Span 6 MHz, Amplitude Ref Level +10 dBm

1. Connect the DUT (Power On) output to SA input. Tune to one, either the 3 MHz, or 4 MHz test tones on the AWG. Adjust the generator (AWG) for 0 dBm on the SA, within 0.1 dB. Tune to the other test tone, adjust the generator for 0 dBm.

SA: Recheck each tone again to make sure nothing has changed. This concludes the initial setup.

Part 2

1. Disconnect the DUT output from SA and connect it to the Reject Filter input (Which has the 20 dB built-in Attenuator). Connect the Reject Filter output to SA RF input.

2. Now look at the 4 IMD frequencies.

• • Span set to 1 kHz
  • Amplitude turn Preamp Off; set Ref Level to -60 dBm, Set Attenuation to Manual and set Attenuation to 0.00 dB.
  • Push the Trace button and look for and select “Avg Times 100”, which is located on the right bottom side of the screen.

The 4 frequencies you will be looking at are: Center Freq 1 MHz (1.004 MHz), 7 MHz  (7.018 MHz), 2 MHz (2.003 MHz) and 5 MHz (5.015 MHz),

3. You should now be seeing the 2IMD product in the center of the display 1 MHz (1.004 MHz). Push the Peak button or push Marker button and use the main tuning knob to tune to the peak of the signal. It will probably vary up and down, but wait for 100 averages and decide what the middle value is and write that down.

4. Tune to the 7 MHz (7.018 MHz) 2IMD product and note its level–write that down.

5. Tune to 2 MHz (2.003 MHz) 3IMD product, this will normally be much weaker, where the SA’s preamp may be needed to see it. Write down that level.
6. Tune to 5 MHz (5.015 MHz), write down that level. You now have measured the four IMD levels.

Use the formula for determining OIP2. (2IMD level – Reject Filter loss at that frequency 1 and 7 MHz) = OIP2.

Determine the OIP2 for both 2IMD frequencies. They are usually different–use the worst case, or specify both Output Intercepts.

Use the formula for OIP3. (3IMD level – Reject Filter loss at that frequency 2 MHz and 5 MHz) /2 = OIP3. Determine OIP3 for both 3IMD frequencies. Usually, they are about the same.

Examples

My reject filter has a -21.6 dB loss at 1 MHz; -20.39 dB loss at 7 MHz for the 2IMD frequencies. There is a -20.65 dB loss at 2 MHz and -22.62 dB loss at 5 MHz for the 3IMD frequencies.

The examples used in the below calculations were taken from the above IMD sweeps.

1 MHz (-109.65 dBm) – (-21.6 dB loss) = (109.65 – 21.6 = 88.5) = +88.05 dB OIP2.

7 MHz (-111.66 dBm) – (-20.39 dB loss) = (111.66 – 20.39 = 91.27) = +91.29 dB OIP2.

Normally you take the worst case and state that, which would be +88.05 dB

2 MHz (~-112.9 dBm) – (-20.65dB loss) = (112.9 – 20.65) = 92.25/2 = +46.13 dB OIP3.

5 MHz (~-111.66 dBm) – (-22.62 dB loss) = (111.66 – 22.62) = 89.04/2 = +44.52 dB OIP3.

Normally these should be very close, otherwise take the worst case, which would be +44.62 +dB
and state that.

System IMD Intercept Test with Band Pass Filters, Combiner and 3 MHz and 4 MHZ Band Rejection Filter connected to the SA

They are all at the noise floor, which is very good. It took adding Band Pass Filters in place of Low Pass Filters to achieve the results Below.

1 MHz (1.004 MHz)  -151.26 dBm

7 MHz (7.018 MHz   -152.45 dBm

2 MHz (2.003 MHz)  -153.51 dBm

5 MHz (5.015 MHz) -152.26 dBm

These are the simple formulas for second and third order IMD, you can take any two frequencies and work out the IMD products

Second order:     F1 + F2;    F2 – F1

Third Order:   2F1 + F2;   2F1 – F2;   2F2 + F1;   2F2 – F1

3 MHz and 4 MHz tones: 3 + 4 = 7 MHz ; 4 – 3 = 1 MHz; 6 + 4 = 10 MHz;  6 – 4 = 2 MHz;  8 + 3 = 11 MHz;  8 – 3 = 5 MHz

Building the Bandstop Rejection Filters

The easiest way to build and tune this filter is to test each Dipole (Tuned Circuit) by its self. It should be 3,250 kHz. Below is a sweep from my VNA, as this is what I used to check and tune each Dipole. I was able to tune the parallel circuits by having one side soldered to its pad and then connect the other end after tuning. You can also use the SIGLENT SSA3000X, SSA3000X Plus, or SVA to tune the filter.. as shown in this note on Filter Testing Using a SIGLENT Spectrum Analyzer

Below is a sweep of the final Band Rejection filter that is being used for IMD testing. There is around 58 dB rejection for 3 and 4 MHZ

Below is the finished 3/4 MHz  Bandstop Filter and Sweep

Below is a sweep of the final Band Rejection filter that is being used for IMD testing. There is around 58 dB rejection for 3 and 4 MHZ

A 20 dB pi pad can be done with 62 ohms shunts and a 270 ohm in parallel with 3300 ohms for the series resistor. (249.6 shown on the diagram. The theoretical value is 248 ohms.)

Both the 3 MHz and 4 MHz Bandpass filters are easy to build if you will tune each pole and install it as you go. I have marked the frequencies in Red for each pole. Also, I have indicated which Micrometal Toroids that were used with the turns required for each pole. You may have to make some adjustments to each of the poles, as there are variations from lot to lot with the toroid core. I also found it helpful to use an LCR meter to make adjustments in the turns count to get the desired inductance. I used an Array Solutions VNA2180 to tune each pole and evaluate the final filter. A SIGLENT SVA1000X VNA can also be used.

4 MHz BPF

3 MHz BPF

AA7U Hybrid Combiner

The loss through the filter is 6.13 dB/5.95 dB and the isolation between the two input ports is 74.58 dB at 3 MHz and 73.97 dB at 4 MHz (Measured with a 50Ω Termination at the output port.) After completing and testing the filter I filled it up with hot melt glue.

Below is a sweep of the Hybrid Combiner between the two input ports and it was terminated with 50Ω at the output port.

This is a sweep showing the two test tones 3 MHz and 4 MHz using the Hybrid Combiner. Notice how sharp they are.

How to take screenshots of the Siglent SA

Insert the thumb drive into the front USB port of Siglent.
You should see a blue USB icon in the upper right-hand corner of the screen.

Hit the File button
You should see a file directory similar to what you would see on a PC.

Under the Folder column, you should see two directories:

Local: free 80.74 MB (your size may be different)
+U-disk0: 748.00 KB/975.88 ME (your size may be different)

On the right-hand side soft keys, the “Save Type” should be PNG.
Hit the button and select JPG (or whatever file type you want – CSV, LIM, JPG, BMP, etc.)

Rotate your frequency tune knob and select your +U-disk0 directory
You should see the files currently on your thumb drive

Hit the Enter button
Hit the Operate button
Hit the Marker button
You should now be back at your main display screen

Setup a screen that you want to save
Hit the Save button
A pop-up window will show you a default file name of Name: JPG1 and an Input type: abc
I like to use a numeric file name, so I hit the +/- button
Now I backspace out the default “JPG1” file name
I enter the numeric name that I want to use. Example: 111
I find it quicker to use quick numeric file names and rename the file once the thumb drive is attached to my PC

Hit the Enter button
You may or may not see a brief text message on the screen about the screen being saved to your thumb drive.

To confirm that the file was saved to your thumb drive, Hit the File button
Use the Frequency control knob and select your thumb drive directory
In the directory listing for the thumb drive, you should see your recently saved screen snapshot

For some reason, the screen sometimes saves to the internal Siglent memory. When this happens, I go through the steps again about setting up a save to the thumb drive. I suspect that my steps are a little flakey in this area.

Once the Flash drive is set up you can save the screenshots by pressing the Save button, which will number the shot and then press the Enter button.

The post Inter Modulation Distortion (IMD) testing appeared first on Siglent.

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

The post Programming Example: Identification String (*IDN?) return with LabVIEW 2018 appeared first on Siglent.