Abstract
In this paper, we present a synchronous passive surface acoustic wave (SAW) sensor system. The SAW resonator structure is composed of LiNbO3 substrate and Au interdigital transducers (IDT). The center frequency of the SAW sensor is 115MHz. The SAW sensor can be used to detect low concentration of gas by monitoring center frequency shift. In this paper, we designed a low noise CMOS oscillator circuit for the SAW sensor and a frequency readout circuit to calculate the frequency variation. The proposed circuit was fabricated in TSMC 0.18μm 1P6M CMOS process technology. The chip operated at an 1V supply for digital circuits and an 1.8V supply for analog circuits. © 2012 IEEE.