Cross talk countermeasures in inductive inter-chip wireless superconnect

Inductive coupling among stacked chips in a package enables 1.2 Gb/s/channel data communications. An array arrangement of the channel increases data bandwidth, while the signal may be degraded by cross talk. In this paper, cross talk is measured and analyzed, and cross talk countermeasures are discussed for the first time. Received signal waveforms by the inductive coupling are measured by embedded voltage detectors on a test chip. The interference-to-signal ratio (ISR) has good agreement between the measurements and calculations from a theoretical model. It is found that cross talk is reduced to being negligibly small at a certain distance. If the channels are arranged at intervals of this distance, ISR is minimized. A technique based on time division multiple access (TDMA) is also proposed to further reduce cross talk.