Testing solutions for USB4 - Universal Serial Bus 4

2020-08-20 | 3 min read

Overview

The USB Implementers Forum (USB-IF) announced USB4 in March 2019 and released the specification in September 2019. Based on the Thunderbolt 3 protocol, USB4 uses a Type-C connector, which enables bonding of two independent 20 Gb/s links into one logical 40 Gb/s link. USB4 supports other standards through ALT mode. The host implements USB 3.2 at 5G / 10G, USB 2.0, and DisplayPort (DP) and can tunnel USB, DP, and PCIe®. Keysight offers a suite of hardware and software tools to help you design and implement USB4.

**Figure 1. Typical USB4 implementation requirements, per USB-IF USB-IF**

USB4 has seen significant changes compared with USB 3.2. These are some of the testing differences in the USB4 implementation:

return loss Tx and Rx	retimer-specific measurements
calibration required for transmitter equalization	cross-talk generation
calibration required for receiver equalization	new jitter measurements
doubling of PHY bit rate from 10 Gb/s to 20 Gb/s	new phase and slew rate measurements
signaling on all four Type-C high-speed pairs	added skew measurements
de-embedding of test cables	common mode interference
new link loss budgets for 10G / 20G	separate jitter cocktails for 10G / 20G / TP2 / TP3
link optimization prior to bit error ratio test	built-in error detector