Inductive coupling among stacked chips in a package enables 1 Gb/s/channel data communications. Array arrangement of the channel increases data bandwidth, while signal may be degraded by crosstalk. In this paper, crosstalk is measured and analyzed, and crosstalk countermeasures are discussed. Received signal waveforms through the inductive coupling are measured by embedded voltage detectors on a test chip. Interference-to-signal ratio (ISR) has good agreement between the measurements and calculations. It is found that crosstalk is reduced negligibly at a certain distance. If the channels are arranged at intervals of this distance, ISR is minimized. A technique based on time interleaving is also proposed to further reduce crosstalk. A 3 × 17 channel array is implemented with the crosstalk countermeasures. The channel pitch is taken down to 50 μm. Inter-chip communication with data rate of 1 Gb/s/channel and bit error rate (BER) lower than 10-9 is demonstrated.
ASJC Scopus subject areas
- Electrical and Electronic Engineering