High-Speed PCBs and Signal Integrity in DDR5 Memory Technology Conversations with Stephen Slater
Keysight Unveils New Tools for DDR5 PCB Design
In the rapidly evolving world of technology, Keysight Technologies has taken a significant step forward by introducing a library of PCI express-gen-5 reference channels for system simulations. This development is especially important for the design of high-speed PCBs, such as those used in DDR5, a significant technology leap from DDR4.
The Importance of Length Matching in DDR5
Length matching plays a crucial role in DDR5, ensuring signals are time-aligned at the end. Precise routing of traces with controlled lengths, often involving serpentine patterns, is essential to achieve this. This meticulous process guarantees that timing margins are preserved, which is vital for the successful operation of DDR5.
Impedance Control and Crosstalk Mitigation
Maintaining a controlled impedance (within ±5% tolerance) on signal traces helps reduce signal reflections that cause distortion and timing errors. This involves selecting proper stack-up materials and carefully designing trace width and spacing. To reduce electromagnetic interference between adjacent high-speed signals, PCB designers increase spacing between traces, add grounded guard traces between sensitive signals, and optimize layer stack-up with dedicated ground planes close to signal layers.
Optimizing Vias and Component Placement
Minimizing via count and using appropriate via sizes reduces signal degradation and impedance discontinuities crucial at DDR5 speeds. Precise component footprints and symmetrical IC packages simplify automated placement and reduce misalignment that can cause signal degradation. Consistent component orientation minimizes complex routing that could introduce additional noise or length mismatch.
Testing and Inspection Support
Incorporating adequate spacing and fiducial marks enables automated inspection and testing, ensuring quality which is critical at high speeds.
Keysight's Tools for High-Speed PCB Design
Keysight's tools, such as the via designer in Pathwave ADS, offer a three-dimensional view and parameterized models for designing vias and pads. The company's High-Speed PCB Design Guide covers topics such as understanding transmission lines and controlled impedance, and the selection process of high-speed PCB materials.
Moreover, Pathwave ADS includes SI pro and PI pro for signal integrity and power integrity analysis, respectively. This comprehensive advanced design system, as mentioned by product manager Stephen Slater, also features a new conducted EMI analysis feature, enabling engineers to check for conducted EMI compliance early in the design process.
The Role of Stephen Slater
Stephen Slater, an expert in high-speed SerDes channel simulations, DDR simulations, and electromagnetic simulations for PCB applications, discusses the importance of simulating the whole system, including connectors and mainboards, when designing high-speed boards for technologies like PCI express-gen 5. He also emphasizes the importance of pre-layout design for DDR5 to ensure enough design margin.
The Shift in Simulation Tools for DDR5
Simulation tools have changed for DDR5, moving away from traditional spice simulation to channel simulation. This shift reflects the increased complexity and speed demands of DDR5 technology.
In conclusion, achieving successful DDR5 PCB design demands meticulous length matching of differential and address/control pairs, rigorous impedance control, crosstalk mitigation via trace spacing and grounded shielding, optimized via usage, and careful component placement—all aligned with manufacturing and inspection processes to ensure reliability at very high data rates. The guidance provided by Keysight's High-Speed PCB Design Guide and the tools within Pathwave ADS are invaluable resources for engineers navigating this challenging but exciting technological landscape.
Technology's Role in Data-and-Cloud-Computing
With the ever-growing significance of data-and-cloud-computing, advanced technology, such as that offered by Keysight's new tools for DDR5 PCB design, proves instrumental in handling high-speed data transmission and storage.
Technology Innovation for Controlled Impedance
In the context of DDR5 PCB design, technology innovation, like Keysight's via designer in Pathwave ADS, contributes to achieving controlled impedance within acceptable tolerances, crucial to maintaining signal integrity and minimizing distortion.
