Chip-to-Chip Proximity Communication

We propose a capacitive-coupling-based method for sensor data retrieval which can be easily integrated with miniature sensor nodes of sub-mm scale. An alignment-independent mechanism is implemented to achieve less than 15% difference in achievable data rate when the sensor chip is randomly dropped on the data retrieval chip regardless of alignment. To enable passive operation of the sensor chip, the data retrieval chip sends power to the sensor chip, as well as timing alignment information. The goal is to allow a passive sensor chip (SC) to be dropped face-to-face onto a data retrieval chip (DR) for read-out without precise positioning. In our system, DR sends power to the SC so that the latter consumes no power during read-out. At the same time, a digital alignment circuit is proposed to overcome misalignment issues when power/signals are sent simultaneously. The alignment detector is an embedded ring oscillator feeding into a counter enabled by a programmable pulse for each DR pad. In this way, we can electrically detect the location of the chip and selectively assign the pads to a receive signal or send power for different drop locations. SC is able to rectify the incoming power from the DR chip and send the NRZ signal back to DR. The test chip is fabricated in 0.13µm CMOS. The active area of the SC and DR chip are 0.014mm 2 and 1.3mm 2 , respectively.The sensor chip is 0.5mm x0.5mm. This project is supported by the Engineering Research Centers Program of the National Science Foundation under award number EEC-9986866.