Finding Sources of Jitter with Real-Time Jitter Analysis Application Note 1448-2

As data rates increase effects of jitter becomes critical and jitter budgets get tighter. Instruments such as Bit Error Ratio Testers (BERT) are optimized for determining the total amount of jitter and worst-case eye-opening in your high-speed digital system and can be used to test for compliance based on industry standards. In addition, some real-time instruments can separate random and deterministic jitter components to predict/extrapolate worst-case total jitter (TJ) and eye-opening based on a user-specified Bit Error Ratio (BER), typically 10-12. But when jitter measurements do not meet a particular minimum standard, or if jitter measurement results are “too close for comfort,” then measuring the amount of component or system jitter is just half of the jitter test equation. Determining the root-cause of jitter is the other half of the test equation. The focus of this paper will be to address some practical “tips & tricks” on using real-time oscilloscopes with jitter analysis and high-speed pulse/pattern generators to separate and time-correlate specific deterministic jitter components to help identify, measure, and view sources of systematic timing errors.