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DSOX4USBSQ USB 2.0 Signal Quality Analysis Application Electrical Testing Notes
1
Preparing for Signal Quality Analysis
Oscilloscope Requirements
The DSOX4USBSQ USB 2.0 Signal Quality Analysis application requires an
Agilent InfiniiVision 4000 X- Series oscilloscope, firmware version 3.10 or
later.
For Hi-Speed
Tests
Hi- Speed tests require a 1.5 GHz bandwidth model oscilloscope.
Hi- Speed tests on a 2- channel oscilloscope with single- ended SMA cable
connections is not supported because the sample rate will not meet the
5 GSa/s rate that is required. Using a differential probe on a 2- channel
oscilloscope works fine.
For Full and Low
Speed Tests
Full and Low Speed tests can be performed with 200 MHz, 350 MHz,
500 MHz, 1 GHz, or 1.5 GHz bandwidth model oscilloscopes.
Full Speed testing is best on a 4- channel oscilloscope because when using
a 2- channel oscilloscope, channels 1 and 2 are non- interleaved and the
sample rate will be below the 4 GSa/s that the USB- IF testing procedures
require. If Full Speed tests are run on a 2- channel oscilloscope,
interpolation is used on the data.
For Optional USB
2.0 Triggering and
Decode in the
Oscilloscope
The optional DSOX4USBH and DSOX4USBFL products (for USB 2.0
Hi- Speed and Full/Low- Speed triggering and decode, respectively) can be
very useful tools for identifying and triggering on packets that you might
want to run the USB signal quality tests on.