Full Function Oscilloscopes for ATE Systems
When testing electronics, it’s hard to beat the general purpose oscilloscope. To validate electronic circuits, engineers depend on the ability to see and measure the signals in their designs. Automated test equipment (ATE) does not typically help with visual troubleshooting, which is challenging for users that have to install, calibrate and troubleshoot the system. These operations require the visualization tools that an oscilloscope delivers, and nothing beats the variety of measurements an oscilloscope provides. To achieve oscilloscope functionality in an ATE environment, users often use soft front panel oscilloscope software with a digitizer. While the software looks like an oscilloscope, it does not have the performance tools traditional oscilloscopes have that are required for troubleshooting.
OSCILLOSCOPE IN A SINGLE PXI SLOT
Keysight’s new InfiniiVision PXIe modular oscilloscopes are designed to provide the usability and performance of a traditional benchtop oscilloscope in a PXIe modular system. Three models allow the choice of bandwidth to fit measurement requirements: the M9241A provides 200 MHz bandwidth; the M9242A, 500 MHz and the M9243A, 1 GHz.
Keysight has been manufacturing high performance oscilloscopes for more than 60 years and leveraged this knowledge to create PXIe oscilloscopes that go beyond merging a digitizer with scope software. The M924XA modular oscilloscopes have the same high performance MegaZoom technology that is used in the popular InfiniiVision 3000T X-Series benchtop scopes. They also share the same optimized user interface, so operating the M924XA oscilloscopes on a PC will look and feel similar to using a familiar oscilloscope.
Oscilloscopes acquire, process and plot data on the screen for user troubleshooting and signal analysis. The display shows multiple waveforms on the screen at the same time. The use of waveform intensity allows quick identification of signal errors that are key to viewing the signal. However, this is more difficult for people who try to use a digitizer with oscilloscope software, and they are frequently frustrated by the signal display limitations. The Keysight modular oscilloscopes address these limitations by providing an industry-leading waveform update rate—up to 1 million waveforms per second—that enables capturing more signal detail. When a runt pulse occurs just a few times per second on a high frequency signal, it takes a high waveform update rate to capture and display the signal (see Figure 1). Using zone triggering, these scopes allow the user to create a trigger based on signal information that is displayed on the screen. With zone triggering, if you can see the event on the display, you can easily trigger on it by simply drawing a box on the screen with a mouse or finger (on a touch-enabled screen) and selecting the desired trigger action (see Figure 2).
Acquiring massive amounts of data from digitizers running oscilloscope software is often required, because they do not have the ability to properly isolate the desired signal in real-time. So large data captures are transferred to the controller for software analysis, hoping that the signal of interest was captured. Oscilloscopes approach this problem by providing tools that enable selective data to be captured, concentrating data acquisition and analysis on advanced parametric information such as runt pulse, rise/fall time, setup and hold. Users can isolate the signal of interest and then use the measurement and analysis tools to determine the signal parameters of interest. Sometimes it is not the data—but simply identifying and counting these events—that proves to be the required information.
While the oscilloscope capability is the primary benefit of Keysight’s M924XA series modular oscilloscopes, it is not the only analysis tool included. The integrated 20 MHz arbitrary waveform generator provides stimulus to activate the circuits and operations of the system being tested, allowing users to capture, edit and replay signals. The waveform generator also provides a quick and easy way to integrate a function generator for more standard signals.
Protocol analysis is often a difficult tool to find integrated into the modular environment; however, the M924xA series has this capability. It includes many advanced protocol tools for triggering and decoding serial communications signals. Whether chip-to-chip communication or military communications, its full-featured protocol analysis capability allows users to define packets of interest for triggering and decoding the communications protocol.
As an example, Figure 3 shows counting CRC errors on an automotive CAN communications link. Sometimes simply counting signal events is all that is required, and all of the oscilloscope trigger events can be converted into an event counter or totalizer. The general purpose counter can be used as an 8-digit frequency counter or an event, providing triggering capabilities that are faster than the display’s 25 million events per second.
Whether performing pass/fail tests to specifications in manufacturing or testing for infrequent signal anomalies, mask/limit testing can be a valuable productivity tool. In the past, ATE systems often required a custom FPGA to provide real-time analysis. Keysight’s new modular oscilloscopes feature powerful hardware-based mask testing that can perform up to 270,000 tests per second. Users can easily create a mask based on a previously captured “ideal” signal and then report the test results as simple counts or as a six-sigma performance benchmark.
Signal analysis is only as good as the probes used to capture the signal. Keysight has a wide range of probing solutions for the modular environment, enabling a variety of different applications to be supported. In addition to the standard range of passive voltage probes, Keysight offers high temperature environmental probes, high sensitivity current probes, high current probes, high voltage probes and power rail probes. Notably, the power rail probe provides a large offset, low noise and 1:1 attenuation with very low loading for making critical power integrity measurements.
ATE operation often places a heavy burden on the software— and the programmer—to perform a correct analysis when characteristics are still under development or the operational performance of the system is being profiled. An oscilloscope is the general purpose “go to” tool for validating the system test configuration, and the integration of an oscilloscope into an ATE system can improve the test operation. It can be a powerful tool to improve system availability through improved calibration and troubleshooting for interactive operation.
Keysight Technologies Inc.
Santa Rosa, Calif.