Design issues of BAW employment in 3D integrated sensor nodes

In the field of wireless sensor node design a wide range of new potentials are opened by means of emerging 3D integration technologies. These technologies enable the design of highly integrated sensor nodes, but the designers face novel challenges, which specialized communications engineers are not familiar with. This work presents an advanced direct tire pressure monitoring system (TPMS) with an overall size below 1 cm3 applying through silicon vias (TSV) and points out two selected design issues arising due to this high level of integration. At first design issues caused by temperature gradients within the 3D integrated chip stack are presented. Multi physics simulations show that a systematical temperature measurement error is introduced by self heating, which would affect the communication performance if unconsidered. Furthermore the radio frequency (RF) characteristics of TSVs, focusing on their electrical efficiency, are investigated. In particular the behavior of TSVs for connecting a bulk acoustic wave resonator with an impedance of 2 kX at 2.1 GHz is evaluated in detail.