Unleashing Innovation with Chiplets and the Advanced Interface Bus (AIB)

Table of Contents

1. Introduction
2. The Concept of Chiplets and Extending Moore's Law
   1. The Advanced Interface Bus
   2. The Protocol Link Layer Workgroup
3. The Advantages of Chiplets and Heterogeneous Integration
4. The Challenges in Developing Complex Systems
5. The Role of Advanced Packaging Technologies
6. The Design Style and Considerations for Chiplets
7. The Cost Considerations of Wires in Packaging
8. The Potential of Chiplets in Large-Scale Systems
9. The Future of Chiplets and the AIB Technology
10. The Open Source Initiative for AIB
11. The Evaluation Criteria for Selecting Protocols
12. The Protocol Needs for Package Level Integration
    1. Existing Protocols for CPU Integration
    2. Existing Protocols for SOC Disaggregation
    3. The Role of the Pipe Interface
13. The Vision for Protocols and Chiplets
14. Conclusion

Chiplets: Extending Moore's Law Through Advanced Interface Bus (AIB)

The concept of chiplets and extending Moore's Law has generated significant interest in the world of semiconductor technology. As the demand for more powerful and complex systems increases, the need for innovative solutions becomes crucial. One of these solutions is the Advanced Interface Bus (AIB), a promising technology that offers a new way of building large systems by leveraging chiplets.

Introduction

Moore's Law, coined by Gordon Moore in 1965, states that the number of transistors on a chip doubles every year. While this law has held true for several decades, the practicality of building monolithic devices with increasing transistor counts has become a challenge. To overcome this challenge, the concept of chiplets emerged, wherein smaller functional units are separately packaged and interconnected to form a larger system.

The Concept of Chiplets and Extending Moore's Law

The Advanced Interface Bus

The Advanced Interface Bus (AIB) is at the forefront of chiplet technology. It provides a platform for heterogeneous integration, allowing different chiplets to be combined seamlessly. AIB enables the mixing of chiplets from multiple semiconductor processes and functions, such as analog and digital logic, to create highly optimized systems.

Pros:

• Heterogeneous integration allows for the utilization of different semiconductor processes and functions, resulting in highly optimized systems.
• AIB provides a flexible and scalable solution to build large-scale systems without the limitations of monolithic devices.
• It offers cost-effective solutions for customers, particularly in sectors such as the US government, where building monolithic devices in large quantities is a challenge.

Cons:

• The adoption and standardization of AIB in the industry are still ongoing, which may lead to compatibility issues and limited availability of AIB-enabled chiplets.
• The development and integration of various chiplets require careful consideration of design techniques and software support.

The Protocol Link Layer Workgroup

To ensure seamless communication between chiplets and their integration into systems, the Protocol Link Layer Workgroup plays a crucial role. This workgroup focuses on defining and evaluating protocols that are compatible with AIB and meet the requirements of both package-level integration and SOC disaggregation.

The Advantages of Chiplets and Heterogeneous Integration

Chiplets offer several advantages over traditional monolithic devices. One significant advantage is the ability to mix processes and functions, allowing for optimized systems. This heterogeneous integration enables the reuse of existing chiplets, reducing the time and cost of developing complex systems. Additionally, advanced packaging technologies further enhance the design possibilities and capabilities of chiplets.

The Challenges in Developing Complex Systems

Building complex systems has become increasingly challenging due to the growing complexity and cost of development. The integration of various components, each with its own set of requirements, poses significant technical and logistical difficulties. Chiplet-based architectures provide a promising solution to these challenges by allowing for modular designs and easier integration of different functionalities.

The Role of Advanced Packaging Technologies

Advanced packaging technologies play a crucial role in chiplet-based systems. These technologies offer alternatives to traditional organic substrates, allowing for different design styles and higher wiring densities. Silicon interposer technology and fan-out technologies enable the use of smaller form factors, reduced costs, and increased design flexibility.

The Design Style and Considerations for Chiplets

The design style for chiplets differs from that of monolithic devices. In chiplet-based systems, wires are not limited by the same constraints as monolithic designs. This allows for the consideration of wire distribution and the optimization of wiring layouts. It is important to strike a balance between wire density, circuit size, and latency to ensure efficient and reliable communication between chiplets.

The Cost Considerations of Wires in Packaging

The cost of wiring in chiplet packaging can vary significantly depending on various factors. While advanced packaging technologies, such as silicon interposer, offer higher wiring densities, they also come at a higher cost. Therefore, it is essential to carefully evaluate the cost and benefits of different wiring options to optimize the design and ensure cost-effective solutions.

The Potential of Chiplets in Large-Scale Systems

Chiplets have gained significant popularity, particularly in sectors such as the US government, where large-scale deployment of devices is required. The ability to select and combine chiplets from a library offers scalability and the advantages of commercial volume manufacturing. Chiplets, when properly integrated, can provide cost-effective solutions while maintaining competitiveness.

The Future of Chiplets and the AIB Technology

The future of chiplets and AIB technology looks promising. The ongoing standardization efforts and open-source initiatives surrounding AIB ensure compatibility and widespread adoption. As the industry continues to embrace chiplet-based architectures, the development of new chiplet-enabled devices and the expansion of the chiplet library are expected. AIB technology will continue to evolve, providing more options and capabilities for chiplet integration.

The Open Source Initiative for AIB

To foster innovation and collaboration, AIB has been released as an open-source project under the Apache 2.0 license. This initiative aims to increase access to AIB technology, reduce upfront development costs, and enable the development of silicon interoperable with Intel's chiplets. The open-source nature of AIB allows for customization and adaptation to specific requirements.

The Evaluation Criteria for Selecting Protocols

The selection of protocols for chiplet integration is crucial in ensuring seamless communication and compatibility. An evaluation criteria matrix, including functional requirements, ordering, virtual channels, error correction/detection, performance, and implementation complexity, has been established. These criteria guide the selection of protocols by considering their capabilities, performance characteristics, and adaptability to different use cases.

The Protocol Needs for Package Level Integration

Different protocols exist for package level integration, depending on the target application and system requirements. For CPU integration, protocols such as CXL and OpenCAPI are commonly used and provide coherent memory models. These protocols enhance the ease of programming for both the FPGA and CPU, enabling efficient communication between chiplets.

The Protocol Needs for SOC Disaggregation

SOC disaggregation requires protocols that facilitate communication between modular modules within a chip. Protocols like AXI and Avalon-ST offer streaming and memory-mapped interfaces, allowing efficient data transfer and low latency. These protocols have wide adoption and offer reliability and performance when integrating chiplets.

The Role of the Pipe Interface

The Pipe Interface is a Parallel interface specifically designed for chiplet integration. It provides a standard low-level interface that can support multiple existing protocols. The pipe interface allows for seamless interoperability between chiplets and the integration of protocols such as Ethernet, DisplayPort, USB, and PCIe into chiplet-based systems. The protocol providers are responsible for creating adapters that bridge the pipe interface and the native Phi interface of the chiplet.

The Vision for Protocols and Chiplets

The ongoing efforts of the Protocol Link Layer Workgroup aim to create a small set of protocols that meet the needs of different chiplet integration scenarios. These protocols will leverage the advantages of AIB and ensure seamless communication between chiplets. By adopting existing protocols and developing new ones when necessary, chiplet-based architectures will be successful in delivering high-performance, cost-effective, and scalable solutions.

Conclusion

Chiplets, coupled with AIB technology, offer a promising path for extending Moore's Law and addressing the growing demand for powerful and complex systems. The combination of heterogeneous integration, advanced packaging technologies, and well-defined protocols enables the seamless integration of chiplets into a variety of applications. As the industry continues to embrace chiplet-based architectures, the potential for innovation and collaboration expands, providing new possibilities for the future of semiconductor technology.

Highlights

• Chiplets and the Advanced Interface Bus (AIB) offer a new approach to extending Moore's Law and building complex systems.
• Heterogeneous integration allows for the mixing of different chiplets from multiple processes and functions.
• Advanced packaging technologies enhance design possibilities and enable multi-chip systems.
• Evaluating protocols based on functional requirements, performance, and implementation complexity is crucial for chiplet integration.
• Package level integration and SOC disaggregation have different protocol needs, but both can benefit from chiplets.
• The Pipe Interface provides a standard low-level interface for seamless communication between chiplets.

FAQ

Q: What is the Advanced Interface Bus (AIB)? A: The Advanced Interface Bus (AIB) is a technology that enables the seamless integration of chiplets in large-scale systems. It allows for the mixing of chiplets from different semiconductor processes and functions.

Q: What are the advantages of chiplets and heterogeneous integration? A: Chiplets offer several advantages, including optimized systems, cost-effective solutions, and the ability to reuse existing chiplets. Heterogeneous integration allows for the combination of different processes and functions, resulting in highly optimized systems.

Q: What are the challenges in developing complex systems? A: Developing complex systems poses challenges such as integration difficulties and increased development costs. Chiplet-based architectures provide a solution by allowing for modular designs and easier integration of various components.

Q: What is the role of advanced packaging technologies in chiplet-based systems? A: Advanced packaging technologies, such as silicon interposer and fan-out technologies, play a crucial role in chiplet-based systems. They offer alternatives to traditional packaging methods and provide higher wiring densities and design flexibility.

Q: What criteria are considered when selecting protocols for chiplet integration? A: When selecting protocols, functional requirements, ordering, virtual channels, error correction/detection, performance, and implementation complexity are evaluated. These criteria ensure seamless communication and compatibility between chiplets.

Q: What is the future of chiplets and AIB technology? A: The future of chiplets and AIB technology looks promising. Ongoing standardization efforts and open-source initiatives will drive widespread adoption and enhance compatibility. The development of new chiplet-enabled devices and the expansion of the chiplet library are expected.

Resources

• Intel Advanced Interface Bus (AIB) GitHub
• Advanced Interface Bus (AIB) Specification