Agilent Technologies DSOX4USBSQ USB 2.0 Instrukcja Obsługi Pobierz pdf (Strona 12)

12 DSOX4USBSQ USB 2.0 Signal Quality Analysis Application Electrical Testing Notes

1 Preparing for Signal Quality Analysis

Probe Requirements

Hi- Speed tests require a differential probe (see “Differential Probe

Connection for Hi- Speed Signal Quality Tests" on page 12) or two

single- ended SMA cable connections (see “Single- Ended SMA Cable

Connection for Hi- Speed Signal Quality Tests" on page 13).

Low and Full Speed host tests require single- ended probes (see

“Single- Ended Probe Connection for Full/Low Speed Signal Quality

Tests" on page 14).

Differential Probe Connection for Hi-Speed Signal Quality Tests

When using a differential probe connection for Hi-Speed signal quality

tests, Agilent recommends the 1131A, 1133A, or 1134A InfiniiMax

differential probes and the E2678A socketed probe head or the E2669A

differential connectivity kit.

When setting up the Agilent 113xA differential probe for connection to the

Hi- Speed signal quality test fixture:

• Attach the socketed probe head to the differential probe amplifier.

• Handle the socketed probe head and header adapter carefully.

• For durability, epoxy can be used to strengthen the assembly. Only

apply epoxy to back (noncomponent) side of probe head.

NOTE

The N2750A Series InfiniiMode probes cannot be used with the Hi-Speed Signal Quality

test fixtures because they have damping resistors and the USB test fixture also has

damping resistors specifically designed for the E2678A socketed probe heads.

However, if you are not verifying signal quality to USB 2.0 specifications (in other words,

you are testing USB signal quality in-circuit with real-world packets), and you just need a

feed-through that will let you probe Hi-Speed signals, you can use the E2646A/B SQiDD

test fixture (normally used for Full and Low Speed testing) and InfiniiMode probes. See

Appendix A, “Probing Hi-Speed Signals with InfiniiMode Using SQiDD as a Feedthrough,”

starting on page 83.

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