Physical Characterization and Hierarchical Compensation of Geometric Deviations in 220 GHz Interconnects

This work presents a systematic investigation into the physical-layer signal integrity challenges encountered in 448 Gbps (448G) interconnect systems operating near the 220 GHz physical boundary. A severe validation gap is identified at this frequency regime, where conventional electromagnetic simulation workflows relying on low-frequency extrapolation become increasingly unreliable. The study addresses three contributions:(1) Characterization of the non-linear loss cliff and associated physical limits at 220 GHz, including copper skin-roughness effects, dielectric extrapolation risk, and BGA via-transition TEM cutoff limitations;(2) A bidirectional digital twin validation framework based on Physics-Informed Neural Networks (PINN), providing a physically grounded extrapolation mechanism despite the lack of accurate material parameters above 100 GHz;(3) An orthogonal Six-Axis Geometric Deviation Model combined with a Hierarchical Compensation Architecture, redistributing environmental and geometric compensation across physical, channel, and system-level layers. By decoupling adaptation time constants between slow environmental drift and fast signal-dependent fluctuations, the proposed architecture is projected to reduce per-channel DSP power by approximately 12%–18% (an architectural-level estimate under modeled large-scale deployment assumptions). The framework may also support deterministic-latency behavior relevant to safety-sensitive networked systems governed by ISO 26262 and AEC-Q100 validation contexts. This preprint is intended to stimulate further academic inquiry into the convergence of physical-layer signal processing, thermodynamic boundary conditions, and functional-safety requirements in extreme high-speed interconnect systems.