Measurement of inductive coupling in wireless superconnect

An inductive inter-chip wireless communication scheme in three-dimensional (3D) stacked chip has been reported to achieve high-speed, low-power, and low-cost inter-chip communication. In this scheme, inductive coupling becomes a fundamental of communication and it should be modeled to realize communication. In inter-chip communication, it is considered that eddy current effect and the reflection of electromagnetic field degrade transmission power. However, there is as yet no report on inter-chip inductive coupling showing these effects. In this study, the scattering parameter of inductive coupling in 3D stacked chip has been measured under three conditions. The first measurement is carried out by changing the inductance alignment vertically and horizontally to verify the estimation scheme of coupling coefficient. The second measurement is carried out to evaluate ground mesh effect on inductive coupling. The third measurement is carried out by changing bulk thickness with constant communication distance to evaluate eddy current effect in bulk. The results show that eddy current does not become a problem and power grid degrades communication efficiency.