Core Viewpoint - The article emphasizes the critical role of the physical layer (PHY) in data communication, particularly in the context of emerging technologies such as artificial intelligence and high-performance computing, highlighting its importance in meeting the increasing demands for bandwidth, low latency, and energy efficiency [3][6][11]. Summary by Sections Importance of PHY - The physical layer has evolved from supporting traditional industries to becoming foundational for AI factories and large-scale data centers, acting as a key driver for data transmission and communication [3]. - As data centers handle massive amounts of data, the significance of PHY increases, especially for AI and HPC workloads that require unprecedented system performance [3][6]. Standards and Applications - Understanding the physical layer is crucial for maintaining competitiveness in various applications, with different standards developed to address specific issues [4]. - Standards like HDMI and DisplayPort illustrate the need for compatibility and efficiency in system design, balancing cost and functionality [5]. Design Challenges - Designing PHY for speeds exceeding 100G presents numerous challenges, including process technology dependence, signal integrity, system design constraints, and packaging integration [8]. - The transition from NRZ to PAM signaling represents a significant shift in technology, necessitating advanced design techniques to meet increasing bandwidth demands [7][8]. Chip-to-Chip Communication - The development of chip-to-chip communication standards, such as UCIe, aims to achieve high bandwidth with low power consumption, which is essential for modern 3D systems [9]. - The integration of multiple dies in a system-on-chip (SoC) architecture requires careful consideration of physical layer protocols to optimize performance [9][10]. Collaboration Between Disciplines - Effective collaboration between analog and digital engineers is necessary to bridge the gap between different domains, ensuring that physical effects are adequately addressed in system design [10][11]. - A comprehensive understanding of how physical effects impact system performance is vital for optimizing designs and achieving desired outcomes [11]. Future Outlook - As the industry progresses towards higher standards like 448G, the challenges will intensify, particularly with the emergence of chip decomposition and optical I/O [11]. - The PHY layer is increasingly viewed as a strategic enabler, necessitating continuous innovation and commitment to pushing technological boundaries [11].