Design of a SAW-based chemical sensor with its microelectronics front-end interface

A surface acoustic wave (SAW) device is used in this work as the sensing element for a chemical sensor that will be embedded in a wireless sensor node. The SAW device is intended to detect the concentration of gaseous mercury in the environment. The microelectronics front-end architecture has been designed at transistor level in a 0.35μm CMOS technology. The SAW device is embedded in a phase-locked loop (PLL) that converts the change of concentration of gaseous mercury into a shift of the loop frequency. Post-layout simulations of the overall sensor including the digital control and read-out blocks have been carried out considering a model of the SAW device described in the Hardware Description Language Verilog-A. Analog tests on the fabricated circuit have demonstrated the functionality of this microelectronics front-end interface.