DLL‐based signal conditioning system for SAW sensor with digital output

Abstract

The use of a delay-locked loop (DLL) for conditioning signals from a surface acoustic wave (SAW) sensor is proposed. The system consists of a reference oscillator and a DLL. The signal generated in the reference oscillator is propagated through a sensitive SAW delay line (SAW-DL). The SAW propagating through this structure has a phase velocity dependent on environmental parameters such as temperature, humidity, mechanical deformation, or analyte concentration. Therefore, the system measures the physical quantity of interest by tracking the delay caused by the sensitive SAW-DL via a DLL. Fully digital DLL is made use of for the delay-tracking, which provides the conversion of the environmental parameter being sensed directly to the digital domain. The system is demonstrated through results from behavioural simulation, using a model of an SAW-DL sensitive to humidity.