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Figure 6 An eye diagram like this one can be generated by a tool set for embedded instrumentation (courtesy Asset InterTech). that leave us? There is a growing interest in embedded test instruments, and the design-for-test movement is allowing nonintrusive embedded instruments to deliver the signal data that the receivers see. “In other words,” says Caffee, “soft access is provided to the hard data that signal-integrity engineers need.” Embedded instruments have been used for years for chip-level characterization, verification, and test. But now, embedded instruments are being used to monitor and report data being received by the receiver. Caffee notes that the embedded instruments are accessed using standard technologies, such as the IEEE 1149.1 boundary-scan (JTAG) test-access port. “JTAG provides access to an external software-based platform that can manage the embedded instruments in the system, as well as compile and analyze the test and measurement data they gather,” Caffee says (Figure 6). As system speed and complexity continue to rise, the way forward looks to be a combination of advanced measurement tools and techniques that work with customized simulation models. In the end, though, the path of least resistance for improving signal integrity looks to be an industry standby: good oldfashioned engineering ingenuity.EDN References Bogatin, Eric, and Alan Blankman, “Use S-parameters to describe crosstalk,” Test & Measurement World, Sept 13, 2012, www.tmworld.com/4396189. “Tips and Techniques for Accurate Characterization of 28 Gb/s Designs,” Agilent Technologies, 2012, http://bit. ly/12m4IZ3 EETimes europe Design Centers Your best connection with expert sources of knowledge 22 EDN Europe | MARCH 2013 www.edn-europe.com


EDNE MARCH 2013
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