USB4 Receiver Testing Made Easy

Introduction

USB4 is the latest iteration of the USB Implementers Forum (USB-IF) standard to use the USB Type-C connector. USB4 doubles the bit rate of USB 3.2 to 40 Gbps, supporting two 20 Gbps physical layer (PHY) lanes. It also has backward-compatibility support for prior USB standards and other protocols such as DisplayPort. Developers must verify the receiver performance of their USB4 and USB Type-C devices according to the updated compliance test specifications to earn USB-IF certification

Use Case Summary

Receiver testing for USB4 is more challenging than USB 3.2 due to the faster data rate and additional compatibility requirements with other standards, such as DisplayPort and Thunderbolt 3. A validation engineer must finely tune and calibrate the bit error ratio tester's (BERT) stress signal amplitude, channel equalization, and insertion loss using a high-performance oscilloscope to achieve accurate stress conditions. Incorrect calibration can lead to invalid stress results. In addition, the engineer must characterize signal impairments such as jitter and common-mode interference

During the receiver test, the BERT injects the stress signal on the lane under test and then performs the BER test. Instead of using the BERT’s error detector, USB4 products implement an error counter that the BERT accesses during the test. This implementation can also complicate the setup, as it differs from most receiver compliance tests

Solution Overview

Keysight’s automated USB4 receiver compliance test solution  provides a fast and easy way to calibrate and test your USB4 receiver devices. The solution calibrates the transmitter equalizer and stress signal, then configures the setup to provide quick and accurate results for all receiver tests defined in the USB4 Electrical Compliance Test Specification

The complete solution includes the Keysight M8040A High-Performance Bit Error Ratio Tester (BERT) running the N5991U40A USB4 Receiver Test application software. You will need a Keysight UXR-Series oscilloscope running the D9120ASIA Advanced Signal Integrity software for pre-test calibration. A thirdparty USB microcontroller test module and test plug connect the system to the device-under-test (DUT).

Summary

• The USB4 standard specifies new test requirements due to faster bit rates.

• Compliance to the standard requires highly accurate receiver testing.

• An automated test solution makes calibration and testing for USB4 compliance easier.