Rambus Inc.

07/29/2024 | Press release | Archived content

Ask the Experts: DDR5 Client Chipset

In this episode of "Ask the Experts," John Eble, Vice President of Product Marketing for Memory Interface Chips at Rambus, discusses the development of advanced chipsets for both server and client systems. He highlighted the need for robust chipsets to maintain the precise timing required in memory subsystems as frequencies increase.

Eble also introduced Rambus' new Client Clock Driver (CKD), which enables DDR5 client DIMMs (CSODIMMs and CUDIMMs) operating at data rates of 6400 Megatransfers per second and above. Applications, led by AI, continue to push for higher data rates and greater memory capacity.

At 6400 MT/s and higher, the CKD buffers and retimes the clock to ensure the synchronous memory system can operate within its timing budget. Absent the CKD, that would not be possible because of jitter on the clock signal.

Eble concluded by underscoring Rambus's expertise in managing power and signal integrity, its high-volume experience, and its strong partnerships in the memory industry across the supply chain.



Expert

  • John Eble, VP of Product Marketing for Memory Interface Chips, Rambus

Key Takeaways

  1. Advanced Chipset Development: Rambus is developing advanced chipsets for both server and client systems to meet the need for more bandwidth and capacity while maintaining the power envelope of memory modules. These chipsets address challenges related to meeting the precise timing required in synchronous memory subsystems.
  2. New Client Clock Driver: Rambus has announced a Client Clock Driver (CKD) that reduces jitter and timing uncertainty in PC memory systems. This CKD re-drives the clock, restoring its amplitude and re-timing the signal to reduce noise. This allows for sufficient margin to close the timing budget as data rates scale to 6400 and beyond.
  3. Managing High Frequency Jitter: The need for the CKD becomes more critical as clock frequencies increase. At higher frequencies, interference mechanisms that reduce signal integrity, such as reflections due to impedance discontinuities and crosstalk, become more pronounced. The CKD helps manage overall jitter and close the timing budget for a robust system.
  4. AI Driven Performance Enhancements: AI applications are driving the need to push up performance in client systems. AI inferencing requires high memory capacity and bandwidth for real-time results from large models. Rambus' CKD supports PCs and memory modules running at 6400 MT/s and extends up to the next speed bin on the roadmap of 7200.
  5. Rambus' Memory Innovation: Rambus brings over 30 years of innovation in the memory space and renowned expertise in managing power integrity and signal integrity. With the CKD, Rambus brings that experience to the client space. The company has a strong track record as a first-class semiconductor product company with high volume experience and strong partnerships in the supply chain, memory industry, and with end customers.

Key Quote

As we continue to go to higher and higher frequencies, we do see the need for a more robust chipset for client DIMMs. The real challenge in these systems, both server and client, is to make sure that the accumulated timing uncertainty or jitter in the round trip is low enough so that there is sufficient timing margin at these very high speeds. Fundamentally, the clock driver is solving a jitter and timing uncertainty problem. It reduces jitter in the synchronous memory system and provides sufficient margin to close the timing budget as we scale up to data rates of 6400 and beyond.

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