USB Testing for USB Design and Compliance

USB testing for USB design and compliance

USB testing for USB design and compliance

Practically all requirements for USB testing both during the USB design process and for USB compliance test on complete devices are met by Rohde & Schwarz test equipment, with a suitable test fixture to connect to the interfaces of the device under test, or probes for directly into the device circuits. On the physical layer, network analyzers provide the highest possible precision for signal integrity test on cables and connectors for USB interface test, including the highest data rates supported by USB.

If ever a group of designs has deserved the description “universal”, then it is the Universal Serial Bus family of interfaces. USB 1.0 was first introduced in 1996 by PC manufacturers to provide both communication and power for PC peripherals such as keyboards, mice, and printers. Subsequently chip-to-chip data communication was added with USB-IC. In the now near 30-year history, the range of functions as power supplies plus a data interface using a single cable, has extended enormously. The maximum data rate has increased from 12 Mbps with USB 1.1 in 1998 to 40 Gbps with USB 4, introduced in 2019. More than 2 billion USB interfaces are sold each year; as manufacturers need to be sure USB interfaces work, there is a large market for USB testing during design, and USB compliance test.

The USB Implementers Forum (USB-IF) is the trade organization responsible for USB specifications and USB compliance test. Manufacturers wishing to use an official USB logo on their equipment must meet the USB-IF test requirements, by either attending a USB-IF Compliance Workshop, or using a USB-IF approved test laboratory. Rohde & Schwarz oscilloscopes are officially approved by the USB-IF for USB Compliance Test at USB-IF Compliance Workshops. All forms of USB device test are supported, including USB message decoding for development and debug. Many devices that comply to a USB specification have not been approved by USB-IF; the manufacturers run their own compliance tests, also supported by R&S oscilloscopes.

Rohde & Schwarz network analyzers are approved by the USB-IF cable certification program for USB Type-C® Cable and Connector Compliance testing.

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.

Our USB testing solution

For USB physical layer tests on cables or connectors, Rohde & Schwarz network analyzers (R&S®ZNA, R&S®ZNB, R&S®ZNBT) provide signal integrity measurements with a dynamic range and maximum bandwidth that comfortably exceeds all USB requirements. For all three analyzer families, option K2 plus K20 provides time domain analysis including eye diagrams and simultaneous frequency domain analysis.

For USB-IF approved compliance test on cables or connectors, Rohde & Schwarz publish.
Step-by-step Methods of Implementation (MOI) for USB Type-C and USB Legacy Cables to use with an R&S®ZNB20 network analyzer

Rohde & Schwarz oscilloscopes from the R&S®RTO6 and R&S®RTP families support decoding USB signals, USB signal integrity test and USB compliance test for all standards from:

  • USB 1.0 to USB 3.2 Gen2, including InterChip (USB-IC) variants,
  • USB-PD 2.0 the bi-directional power source, sinking or sourcing up to 100 W (5 A @ 20 V).

For both development and design verification, and compliance test, a 4-channel oscilloscope is ideal: The bandwidth requirements depend on the USB standard to test and the application, range from 1 GHz – 16 GHz.

  • For USB designs, separate options support trigger and decode for USB signals depending on the USB standard. Debug and analysis tools include eye diagrams as a simple graphic tool for evaluating the quality and integrity of data signals, de-embedding to characterize the influence of the test setup on measurements, and jitter and noise analysis.
    For compliance test, separate options according to the family of standards to investigate, cover all supported USB standards.
    For an approved compliance test, a test fixture from the USB Forum to connect the device under test to the oscilloscope is required. For USB pre-compliance testing, Rohde & Schwarz test fixtures are completely suitable.
    To simplify running USB compliance test, the R&S®ScopeSuite automates much of the compliance test procedure.
    For on-board test during development, Rohde & Schwarz supplies a full range of differential, single ended and current probes to meet all connection needs.

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.

MOI documents

Method of Implementation (MOI) USB Type-C to Legacy Adapter Assembly Compliances Tests

This application note describes Methods of Implementation (MOI) for precise, fast, and error-free compliance testing of USB Type-C to legacy adapter assemblies supporting USB3.1 Gen1, and USB2.0. Based on 5 Gbps signaling per lane with vector network analyzers from Rohde & Schwarz.

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Method of Implementation (MOI) USB Type-C to Legacy Cable Assembly Compliance Tests

This application note describes Methods of Implementation (MOI) for precise, fast, and error-free compliance testing of USB Type-C to legacy cable assemblies supporting USB3.1 Gen2, USB3.1 Gen1, and USB2.0. Based on 5 Gbps signaling per lane with vector network analyzers from Rohde & Schwarz..

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Method of Implementation (MOI) for USB3.2 legacy cable test

This application note describes Methods of Implementation (MOI) for precise, fast, and error-free compliance testing of USB 3.2 Legacy Cable Testing for USB Type A, Type B, and Micro family connector types. Based on 5 Gbps and 10 Gbps signaling per lane with vector network analyzers from Rohde & Schwarz.

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Method of Implementation (MOI) for USB Type-C to Type-C Cable Assembly Compliance Tests

This application note describes Methods of Implementation (MOI) for precise, fast, and error-free compliance testing of USB Type-C to Type-C cable assemblies supporting USB4 Gen3, USB4 Gen2, USB 3.2 Gen2, USB3.2 Gen1, and USB2.0.

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Related webinars

USB 3.2 electrical compliance testing

This webinar is intended for engineers who work on high-speed digital design and test.

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USB 3.2 compliance testing

This webinar is intended for engineers who work on high-speed digital design and test. In particular, we will be focusing at USB interfaces. After a quick introduction into USB technology we will be discussing the details of USB 2.0 and 3.2 compliance testing. The webinar will enable you to learn common signal integrity issues, and we will be guiding you through related challenges.

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Compliance testing and signal integrity debugging of USB 3.2 interfaces

This webinar is intended for engineers who work on high-speed digital design and test. In particular we will be looking at USB interfaces. We will be starting with an introduction in the purpose, the technology and the different standards and applications of this digital interface. Challenges, specifications and test procedures open the webinar’s test & measurement core.

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Related documents

Conformance Test failed. What now?

Conformance tests are performed on serial data interfaces such as USB, HDMI and PCI Express to ensure interoperability between electronic devices and accessories. In cases where signal integrity problems are encountered, the R&S®RTP oscilloscope supports root cause analysis by providing powerful tools such as eye diagrams, jitter and noise separation as well as time domain reflectometry.

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Rohde & Schwarz and Eurofins Digital Testing bring advanced testing kit to high speed interface compliance test programs

The growth in high speed communications technologies has increased demand for compliance and compatibility testing in line with an ever increasing number of industry standards. Rohde & Schwarz is partnering with Eurofins Digital Testing to provide access to the latest high speed signal analysis and compliance testing tools with the R&S®RTP164 high-performance oscilloscope. Eurofins Digital Testing also has plans to provide certification services for high speed commu­nications technologies such as USB. Learn more in our flyer.

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Real-time deembedding with the R&S®RTP

Deembedding the test fixtures and cables is important for proper measurements in USB. With the option R&S®RTP-K122, the R&S®RTP offers real-time deembedding to measure and trigger on deembedded signals in real-time.

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Optimizing differential measurements on high-speed interfaces

The R&S®RT-ZM modular probe system offers measurements in differential mode and common mode as well as single-ended measurements. The ground connection prevents the circuit from floating and ensures stable and reproducible signals.

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Comparison of jitter measurements in time and frequency domain

Jitter can be measured in the time and frequency domains. While scope based TIE measurements allow measurement of all jitter types, phase noise analyzer based jitter measurements are restricted to clock signals – but offer unrivalled jitter sensitivity.

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Precise measurements on high-speed digital PCBs with the R&S®ZNB

With the R&S®ZNB-K20 extended time domain option, the R&S®ZNB provides accurate tests of eye diagram, rise time, skew, etc. on digital high-speed signal structures. Additional deembedding tools can be installed to remove the effects of lead-ins and lead-outs.

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Jitter Analysis with the R&S®RTO Oscilloscope

Jitter is a key concern in signal integrity analysis. With the R&S®RTP-K12 and R&S®RTO-K12 options, Rohde & Schwarz oscilloscopes can measure TIE jitter, period jitter, cycle-cycle jitter, etc. and offer result displays such as jitter track, histogram or spectrum.

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