Oscilloscope Requirements in Automatic Test Equipment (ATE) Systems

            By Don Schoenecker, Oscilloscope Product Planner, Keysight Technologies

It’s hard not to mention the versatility of an oscilloscope when it comes to testing electronic devices. To verify electronic circuits, engineers need to be able to see and measure the signals in their designs. Automatic test equipment (ATE) does not typically offer a lot of visual troubleshooting, which can be a challenge for users who must install, calibrate, and troubleshoot the system. These operations require visualization tools, which oscilloscopes provide.

No other device offers more measurement tools than an oscilloscope. To implement oscilloscope functionality in an ATE environment, users typically use SFP (Software Front Panel) oscilloscope software in a digitizer. However, while the software looks like an oscilloscope, it does not have the high-performance tools found in a traditional oscilloscope for troubleshooting. 

Provides true benchtop oscilloscope performance in a single PXI slot

Keysight's newest M9241A (200 MHz), M9242A (500 MHz), and M9243A (1 GHz) InfiniiVision PXIe modular oscilloscopes are designed to bring the usability and performance of traditional benchtop oscilloscopes to PXIe modular systems. Keysight has more than 60 years of experience in manufacturing high-performance oscilloscopes, and has leveraged that knowledge to create PXIe oscilloscopes that go beyond the simple combination of a digitizer and oscilloscope software.

Figure 1: The Keysight M9243A is a 1 GHz, 2-channel oscilloscope with superior visualization and troubleshooting capabilities.

Keysight's M924XA modular oscilloscopes feature the same high-performance MegaZoom technology that is also used in the popular InfiniiVision 3000T X-Series benchtop oscilloscopes. They also have the same optimized user interface, so operating the M924XA oscilloscopes on a PC feels like using a familiar traditional oscilloscope.

Waveform Visualizer

An oscilloscope acquires data, processes it, and plots it on a screen for the user to troubleshoot and analyze signals. This display shows multiple waveforms superimposed on one another on the screen at the same time. Signal errors can be quickly identified using waveform intensity, which is critical to observing signals. However, this is more difficult for users trying to use a digitizer and oscilloscope software, and they are often frustrated by signal display limitations. 

Figure  2 : When short pulses occur a few times per second on a high frequency signal , a high waveform update rate is required to capture and display this signal. Advanced triggering can be used to further isolate the signal.

Keysight's modular oscilloscopes eliminate these limitations by providing industry-leading waveform update rates (up to 1,000,000 waveforms per second) to capture more signal details. These oscilloscopes allow users to use zone triggering to create triggers based on the signal information displayed on the screen. With zone triggering, if you can see the event on the display, you can easily trigger on that event by simply drawing a box on the screen with your mouse or finger (on a touch screen) and then selecting the desired trigger action.

Figure  3 : To isolate a signal using a nonmonotonic edge , simply draw a box around the signal of interest and select “ Must Intersect . ”

Reduce the amount of data collected

Users often need to acquire large amounts of data from digitizers running oscilloscope software because they do not have the ability to properly isolate the desired signal in real time. The large amount of captured data is transferred to a controller for software analysis in the hope that the signal of interest has been captured.

Oscilloscopes address this problem by providing a range of tools that selectively capture and focus data acquisition and analysis based on high-level parametric information (runt pulses, rise/fall times, setup and hold, etc.). This allows the user to isolate the signal of interest and then use measurement and analysis tools to determine the signal parameters of interest. Sometimes data is not needed at all, just identifying the event and counting it is enough to prove it is the information needed.

Tool Integration

While the oscilloscope function is the primary advantage of the Keysight M924XA Series modular oscilloscopes, it is not the only analysis tool included in this instrument. The integrated 20 MHz arbitrary waveform generator provides stimulus to activate the circuits and operations of the system under test so that users can capture, edit and playback signals. The waveform generator also provides a quick and easy way to integrate a function generator to generate more standard signals.

Protocol analysis tools are often difficult to integrate into a modular environment, but the M924xA series has this capability. It includes many advanced protocol tools for triggering and decoding serial communication signals. Whether it is chip-to-chip communication or military communication, its full-featured protocol analysis capabilities allow users to define packets of interest, trigger on them, and decode the communication protocol.

Figure  4 : Using an advanced protocol analysis tool to decode serial communications and analyze events. Here we can see the  CRC error count on an automotive  CAN communication link.

As mentioned previously, sometimes a simple count of signal events is all that is needed. All oscilloscope trigger events can be easily converted into an event counter or accumulator. The general purpose counter can be used as an 8-bit frequency counter or as an event counter, providing triggering capabilities even faster than the display rate of up to 25 million events per second.

Waveform template

Whether performing pass/fail testing to specified standards in manufacturing or testing for rare signal anomalies, mask/limit testing is an important productivity tool. In the past, ATE systems often required custom FPGA work to provide real-time analysis. Keysight's latest modular oscilloscopes feature powerful hardware mask testing capabilities that can perform up to 270,000 tests per second. They also enable users to easily create masks based on previously captured "ideal" signals. They can then report test results as simple counts or six sigma performance benchmarks.

Detection

Signal analysis is only as good as the probes used to capture the signal. Keysight offers a wide range of probing solutions for modular environments to support a variety of different applications. In addition to standard passive voltage probes, Keysight has added high temperature environment probes, high sensitivity current probes, high current probes, high voltage probes, and power supply probes.  

It is worth mentioning that the power probe has large offset, low noise and 1:1 attenuation ratio, which has very low loading and can be used for critical power integrity measurements. 

The Value of Oscilloscopes in ATE

When features are still under development, or when characterizing system performance, ATE operations often place a heavy burden on software programs (and programmers) to perform proper analysis. Oscilloscopes are a general-purpose, "catch-all" tool for validating system test configurations. Incorporating an oscilloscope into an ATE system can further improve test operations. As a powerful tool, an oscilloscope can significantly increase system availability by improving calibration and troubleshooting interactive operations.