Leveraging DDR5 RCDs for High-Speed DDR5 Protocol Analysis: A Novel Approach to RDIMM Testing

Ensuring memory data integrity is essential for the reliable operation of modern compute infrastructures. As data processing demands surge, driven by advancements in fields such as artificial intelligence, DDR (Double Data Rate) memory speeds have escalated rapidly. Originally specified to reach a maximum speed of 6400 MT/s [1], DDR5 is now projected to exceed 9600 MT/s to meet the increased requirements for memory bandwidth. With data rates currently approaching 8000 MT/s, verifying that both memory controllers and DRAM (Dynamic Random-Access Memory) chips adhere to JEDEC (Joint Electron Device Engineering Council) specifications is becoming increasingly crucial to maintaining performance and reliability. For a DDR5 RDIMM operating at 8000 MT/s, clock, DQ (Data), and CA (Command & Address) signals run at 4 GHz, requiring precise handling in a dense layout of hundreds of high-frequency, single-ended traces. Probing such a high volume of multi-gigahertz signals simultaneously presents significant challenges for traditional test equipment. Currently, only a few protocol analyzers on the market are capable of this level of probing, and all face bandwidth limitations. This article introduces a novel technique that leverages a standard DDR5 RCD (Registering Clock Driver) as a probing front end, enabling more effective analysis of the DDR5 RDIMM (Registered Dual In-Line Memory Module) bus. This technique extends the capabilities of bandwidth-limited protocol analyzers to probe DDR5 buses operating well beyond their rated bandwidth.