Randy White

In the final installment of his article series "DDR5 Electrical and Timing Measurement Techniques," Randy White explores how following a standard workflow for setting up thresholds and timings to distinguish bursts in DDR5 memory interfaces can make design validation much more efficient, ultimately ensuring compliance with specifications and improving system margin by identifying and resolving any issues, especially those related to either read or write transactions.

In this article, Randy White discusses variations in clock timing and how this can impact the reliability of a memory system. White highlights the importance of considering probe calibration, random jitter removal, and controlling bandwidth for accurate measurements, providing examples that demonstrate why care must be taken during probe attachment, calibration, and using a jitter/noise analysis application to evaluate jitter levels, therefore ensuring memory reliability.

Optimizing DDR5 memory system validation involves a strategic focus on probe and interposer solutions for in-system measurements. The selection of probe architecture, whether RC or RCRC, plays a key role in managing probe loading. To make the right choice, evaluating source impedance and signal characteristics, especially for bursted signaling, is essential. As DDR5 continues to evolve at higher speeds and reach its top speed phase, integrating non-ideal loading modeling within simulations and effectively de-embedding probe and interposer effects become critical components of a comprehensive testing plan.s

This article shows the impact of using one of the first DDR4-3200 FPGA memory controllers, the Xilinx Versal, interfaced to a UDIMM to show a method for accurately correlating signal integrity simulations to measurement.