Analog Signals Join Digital Patterns In Serial Data
Testing receiver elements for the latest high-speed serial bus protocols, including SATA, PCI-Express and many more, is a challenge for engineers and their equipment alike. Specific tests are required before a product can receive "logo" certification under these standards. Established tools such as data or pattern generators have a proven track record for evaluation and compliance testing of these demanding technologies. Using external modifiers such as power combiners and noise generators, data generators can provide most of the necessary signal formats. Currently, most serial standards are based on results achieved with these purely digital tools.
With fast digital-to-analog converters and faster sample clock capabilities, a new generation of arbitrary waveform generators is coming forward as a supplement to digital instrumentation -- or even as an alternative. Since the testing requirement is, in effect, to replicate real-world transmission path effects, the AWG presents a compelling solution for the test problem. It can embed aberrations such as jitter and overshoot in the signal itself. And it can apply signal conditioning such as de-emphasis in the same way -- as part of the original signal.