How to Test DisplayPort 2.1 Cable Compliance

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Testing DisplayPort cables based on compliance test specifications

Validating the new DisplayPort 2.1 (DP 2.1) standard cable requires a series of S-parameter and time-domain measurements based on compliance test specifications (CTS). The increased bit rates of 80 Gbps in DP 2.1 cable to support ultra-high definition (UHD) and transfer rate bring additional signal integrity challenges and more stringent test requirements for compliance. A DP80 cable running at an ultrahigh bit rate of 20 GHz (UHBR20) per lane is mandatory to test integrated insertion loss, return loss, and crosstalk at Nyquist frequency with different combinations of high-speed data lanes.

The conventional method of testing DP 2.1 cables using a four-port vector network analyzer (VNA) is extremely manual — calibration, measurement setup, and test execution are time-consuming and prone to user errors. Test engineers need modular multiport network analyzers such as the Keysight PXIe vector network analyzer (VNA) or a 20-port switch matrices system. Both systems can manage multiport measurements that help reduce tedious manual port reconnection. Together with compliance test software, these solutions ensure that users meet compliance test requirements efficiently.

DisplayPort 2.1 cable compliance test solution

Validating DisplayPort 2.1 DP80 and DP54, cables requires up to 28 sets of S-parameter measurements with compliance test tools to verify the results. The Keysight DisplayPort cable compliance test solution enables complex compliance test automation and provides a detailed test report to ensure product interoperability. The solution comprises the Keysight E5080B VNA running the Keysight S96011B enhanced time domain (E-TDR) application and Keysight S94DPPCB DisplayPort cable compliance test software. The Keysight L8990M-0LZ switch matrices system enables four to 20-port switching that fully automates the compliance test process with a 90% improvement in test throughput.

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