Analysis and Design of Oblong Coils and Standard-Cell-Based Receiver for Area-Efficient Edge-Coupled Inductive Coupling Transceiver

Proximity inductive coupling interfaces provide a low-cost, high-yield solution for 3D assembly, thanks to their compatibility with standard CMOS processes. However, they suffer from challenges related to the design complexity of both the coil and the receiver. To address these issues, this work proposes a comprehensive approach that includes an analytical coil design methodology applicable to edge-coupled configurations, an oblong coil structure to improve layout efficiency, and a standard-cell-based receiver architecture that enables simplified and scalable implementation. The proposed oblong coil achieves a 4.5 times improvement in area efficiency compared to traditional square coils, while maintaining adequate coupling strength and crosstalk tolerance, as validated through a test chip fabricated in a 40 nm CMOS process. The proposed receiver leverages bias sharing and a digitally tunable, standard-cell-based hysteresis comparator, resulting in 0.23 times the area and 0.37 times the energy consumption relative to a conventional analog comparator, as confirmed through simulations in a 16 nm FinFET process.