Miniaturization of a wireless sensor node by means of 3D interconnects

This work presents an advanced sensor node for direct tire pressure monitoring with an overall size below 1 cm3, where the applied components are arranged in a 3D integrated stack for high compactness, improved thermal behavior, and enhanced robustness for pressure, inertia, and temperature sensing. The utilized through silicon via (TSV) technology is introduced and the wide range of resulting issues for the design of a sensor node are considered. In particular, the radio frequency (RF) characteristics of TSVs are investigated in detail focusing on their electrical efficiency. Finally an optimized TSV design is presented, which allows the connection of a Bulk Acoustic Wave (BAW) resonator with an impedance of 2 k at 2.1 GHz. Thus, all required types of interconnections within the sensor node can be realized by means of the TSV technology.