Using two signal generators, two amplifiers, and two mixers, you can build a test setup that exercises PAM4 receives for tolerance to jitter and to different eye heights. Changing these conditions lets you characterize the receiver and perform compliance tests.
Alexander Katsman is with ADSANTEC (ADSANTEC Corporation is a California-based high-speed mixed signal IC design house that specialises in providing cutting-edge custom built ASICs for the test and measurement, telecommunication, and computing markets.) Alexander is a UCLA graduate. He has been on the ADSANTEC team from 2008-2010 and rejoined the team at the end of 2015. At ADSANTEC, Alexander is in charge of Business Development and Marketing, helping spread knowledge of ADSANTEC's High-Speed / High Frequency Product Lines.