USB testing for USB design and compliance

Your USB testing challenges

• Testing signal integrity (signal quality); monitoring individual bits for occasional und unpredictable glitches, or analyzing bit sequences for jitter and noise either within the device layout or as output from the device.
• Checking conformance to a USB standard in preparation for compliance test.
• USB Compliance test to meet either the official USB Implementers Forum (USB-IF) requirements, or to a manufacturer’s own conformance approval.
• Decoding transmitted USB messages for design debug and verification.

Benefits of our USB testing solution

Decoding data is a particular challenge with USB test. All variations of USB convert data bytes to transmission characters for data communication, to reduce transmission errors by achieving DC balance and bounded disparity (long term, 50% “1” and 50% “0” are transmitted). The conversion makes reading data directly from the data stream impossible. Clock Data Recovery software is essential to postprocess the acquired signal and extract the embedded clock required to decode data. Rohde & Schwarz trigger and decode oscilloscope tools include clock recovery for all supported USB standards and provide a selectable range of protocol layers; from signal properties to data content.

To evaluate the quality and integrity of data signals, eye diagrams are a simple but powerful graphic tool for monitoring individual bits for occasional und unpredictable glitches, and analyzing bit sequences for jitter and noise. Speed of capture and analysis is key for debugging. Based in the unique digital trigger hardware, R&S oscilloscopes provide eye analysis in close to real time.
To simplify running USB compliance test, the Rohde & Schwarz ScopeSuite automates much of the compliance test procedure, and guides all the required user activities. A Wizard provides fully illustrated step-by-step instructions for connecting the oscilloscope, the probes, the test fixture and the device under test through to the end of the test sequence, including setting user-defined limits. All the necessary settings and the test sequences are controlled automatically. Both random and deterministic jitter are tested as part of the USB compliance procedure, requiring different waveforms (clock and data).
Rohde & Schwarz oscilloscopes with an integrated arbitrary waveform generator can switch between the compliance test patterns as required, completely automatically. Once all the tests in the compliance procedure are completed, the ScopeSuite includes functions to document the results.
For physical layer signal integrity test, Rohde & Schwarz network analyzers provide simultaneous measurements in the time and frequency domains. De-embedding removes the fixture and channel effects from a measurement setup to create an eye diagram that is closer to the true signal. Advanced analysis tools include adding gain to the signal, and compensation for frequency response.

Run compliance tests on USB Type-C® cables and connectors with confidence that a positive test result for a correctly completed compliance test procedure meets all the requirements of the USB-IF cable certification program for USB Type-C® Cable and Connector Compliance testing.