Chiplet architectures with advanced interconnect fabrics represent a paradigm shift in chip design, disaggregating traditional monolithic chips into smaller, specialized dies interconnected within a single package. This approach enables the mixing and matching of chiplets manufactured using different process nodes, optimizing performance, cost, and time-to-market for complex systems-on-chip (SoCs). Advanced interconnect fabrics, such as Intel's Advanced Interface Bus (AIB) or the open-source Universal Chiplet Interconnect Express (UCIe), provide standardized interfaces for chiplet-to-chiplet communication. These interfaces currently support data rates of 16-32 GT/s per pin, with next-generation designs targeting 64 GT/s and beyond. UCIe, in particular, aims to establish an industry-wide standard, potentially fostering a more diverse and competitive chiplet ecosystem. Compared to monolithic designs, chiplet architectures offer several advantages. They allow for the use of optimal process nodes for different functions, potentially combining cutting-edge compute dies with more mature I/O or analog chiplets. This flexibility can lead to improved overall system performance and cost-effectiveness. Additionally, manufacturing smaller dies can significantly improve yield, as the probability of defects increases exponentially with die size.

In contrast to optical interposers or silicon photonics solutions, chiplet architectures primarily rely on electrical interconnects for die-to-die communication. While this may limit bandwidth over longer distances compared to optical solutions, advanced packaging technologies like embedded multi-die interconnect bridge (EMIB) or silicon interposers can achieve very high bandwidth densities over short distances, often exceeding 2 TB/s/mm².

Thermal management in chiplet designs can be both a challenge and an opportunity. The disaggregated nature of chiplets allows for more targeted cooling solutions, potentially improving overall thermal performance compared to monolithic designs. However, managing heat dissipation across multiple dies with varying power profiles requires careful design consideration. Power delivery poses unique challenges in chiplet architectures. Ensuring consistent power delivery across multiple chiplets, each with potentially different voltage and current requirements, necessitates advanced power delivery network (PDN) designs. This contrasts with optical interposer solutions, where power delivery for optical components is often less complex due to their relatively low power consumption. The chiplet approach offers significant flexibility in design, allowing for rapid iteration and customization of products by swapping or upgrading specific chiplets. This modularity can lead to faster time-to-market and more cost-effective product updates compared to redesigning entire monolithic chips. However, this flexibility also introduces challenges in ensuring consistent performance across different chiplet configurations, requiring robust design methodologies and extensive validation. Standardization of chiplet interfaces remains an ongoing process, with industry consortia working to establish widely adopted standards. The success of these standardization efforts will be crucial for realizing the full potential of chiplet architectures, enabling a more diverse and competitive ecosystem similar to the PC industry's standardized components.

Compared to through-silicon via (TSV) technology, chiplet architectures offer more flexibility in die composition and can potentially be more cost-effective for certain applications. However, TSVs excel in achieving extremely high bandwidth density for vertically stacked dies, which can be advantageous for memory-intensive applications. As these technologies mature, we may see hybrid approaches combining elements of chiplet architectures, optical interconnects, and advanced packaging technologies. For instance, future designs might incorporate chiplets with integrated silicon photonics for long-reach communications, while using high-bandwidth electrical interconnects for short-reach die-to-die links. This hybrid approach could leverage the strengths of each technology: the flexibility and yield benefits of chiplets, the high bandwidth and low power consumption of optical interconnects for longer distances, and the high density and maturity of electrical interconnects for short-reach communications.

Worth watching:

• NVIDIA (US): uses chiplets to build faster interconnects between its GPUs. With the upcoming Grace Hopper Superchip, NVIDIA integrates multiple dies to improve compute density and bandwidth for AI workloads. The NVLink interconnect, which allows fast communication between GPUs, is expected to be extended with new chiplet-based designs that can reduce latency and increase data throughput for AI clusters.
• AMD (US): develops Infinity Architecture, which uses Infinity Fabric to interconnect chiplets. This technology is being scaled up to address the needs of AI and high-performance computing clusters, where interconnect speed and bandwidth are critical. AMD's MI300 series is expected to leverage chiplet-based designs to combine GPUs and CPUs, providing an efficient solution for AI workloads that need a combination of compute and memory.
• Intel (US): Sapphire Rapids processors, used in conjunction with Habana Gaudi accelerators, employ Advanced Interface Bus (AIB) and EMIB technologies to facilitate inter-chip communication. Intel is actively pushing towards a disaggregated chiplet architecture that allows flexible combinations of compute tiles to better support AI model scaling and interconnectivity, targeting the needs of large AI clusters. Additionally, Intel's Foveros packaging enables 3D stacking of chiplets, allowing more integrated and bandwidth-efficient solutions.