Mastering Chiplet Design

The semiconductor industry is undergoing a fundamental shift from monolithic chip designs to chiplet-based architectures. This modular approach promises enhanced performance, cost efficiency, and scalability, but it also brings unique system-level verification challenges that design teams must overcome.

Chiplet systems break different functions into smaller, separate dies, improving yield and reducing costs. Rather than fabricating a massive single chip where one defect can ruin the entire device, chiplets allow manufacturers to combine smaller, proven components into a complete system. This approach offers significant advantages:

• Improved cost efficiency through better yields on smaller dies
• Enhanced scalability by mixing and matching different chiplets
• Flexibility to combine different process nodes and technologies

However, this innovation comes with a price. Where monolithic designs kept all functions on a single die, chiplet systems must now manage complex die-to-die (D2D) communication across multiple components. This introduces significant challenges:

1. Increased design complexity in managing inter-chiplet communication
2. Verification complexity in ensuring end-to-end system performance
3. Signal integrity concerns across chiplet boundaries
4. Thermal and power management across distributed components

Standards Drive Success: The UCIe Solution
Recognizing these challenges, the industry has rallied around the Universal Chiplet Interconnect Express (UCIe) standard. UCIe provides essential guidance for chiplet electrical layer design, defining operating data rates (4, 8, 12, 16, and 32 GT/s) and establishing critical signal integrity specifications.

The UCIe standard tackles signal integrity through three critical metrics that work together to ensure reliable chiplet communication. At the heart of signal quality assessment are eye mask requirements, which define the acceptable boundaries for signal transitions and help engineers visualize whether their designs maintain clean, readable signals at high speeds.

The standard also establishes voltage transfer function (VTF) loss specifications, essentially creating a benchmark for acceptable signal degradation as data travels between chiplets. Think of it as a quality threshold—your design must demonstrate that signals remain strong enough above this threshold to ensure reliable communication.

Finally, VTF crosstalk limits address one of the most challenging aspects of dense chiplet packaging: electromagnetic interference between adjacent signal paths. As chiplets pack more functionality into smaller spaces, managing this interference becomes crucial for maintaining signal integrity across the entire system.

EDA Tools: The Key to Chiplet Success
Traditional verification approaches fall short when dealing with chiplet complexity. Where monolithic designs could rely on established simulation methodologies and relatively straightforward signal-path analysis, chiplet systems introduce a web of interdependencies that legacy tools struggle to handle. Engineers find themselves wrestling with multiple technology boundaries, varied physical dimensions, and the intricate dance of signals crossing from one die to another through complex packaging substrates.

The challenge isn’t just technical—it’s also practical. Design teams often spend countless hours manually configuring simulations, struggling to accurately model the complete signal path from transmitter to receiver across multiple chiplets. What worked for single-die verification simply doesn’t scale to the multi-dimensional puzzle of chiplet systems.

This new reality demands a fundamental shift in how we approach verification. Design teams need EDA software that goes beyond traditional capabilities to offer:

• Standards-focused capabilities that support chiplet interface specifications
• Complete system analysis from transmitter to receiver
• User-friendly interfaces that integrate into existing workflows

Modern chiplet-specific EDA tools can analyze IBIS-AMI models for both transmitters and receivers, automatically handle equalization settings, manage forwarded clocks, and configure termination resistances—all while maintaining compliance with UCIe standards.

Smart verification workflows have become essential. Advanced tools now include features like intelligent connection wizards that can automatically connect dozens of signal lines based on naming conventions, dramatically reducing setup time. Design exploration capabilities allow engineers to sweep parameters and generate comprehensive reports, accelerating the optimization process.

Embracing the Chiplet Challenge
As the semiconductor industry continues its transition to chiplet-based designs, the combination of industry standards like UCIe and purpose-built EDA tools becomes increasingly critical. Success requires not just understanding the technical challenges but having the right tools to address them efficiently.

The chiplet revolution is here, offering unprecedented flexibility and cost advantages. By leveraging standards-compliant EDA solutions, design teams can navigate the complexity and deliver innovative, high-performance systems that meet the demands of emerging applications in AI, 5G/6G communications, and automotive electronics.

The future of semiconductor design is modular, and with the right approach, the challenges of chiplet systems become opportunities for innovation.

[This post was created out of an article that appeared in Keysight’s SHIFT LEFT Journal, exploring how EDA tools and methodologies are evolving to meet the demands of next-generation semiconductor design.]