An electronic nose (E-Nose) is one of the applications for surface acoustic wave (SAW)\nsensors. In this paper, we present a low-noise complementary metalââ?¬â??oxideââ?¬â??semiconductor (CMOS)\nreadout application-specific integrated circuit (ASIC) based on an SAWsensor array for achieving\na miniature E-Nose. The center frequency of the SAW sensors was measured to be approximately\n114 MHz. Because of interference between the sensors, we designed a low-noise CMOS frequency\nreadout circuit to enable the SAW sensor to obtain frequency variation. The proposed circuit was\nfabricated in Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 Ã?¼m 1P6M CMOS process\ntechnology. The total chip size was nearly 1203 Ã?â?? 1203 Ã?¼m2. The chip was operated at a supply\nvoltage of 1 V for a digital circuit and 1.8 V for an analog circuit. The least measurable difference\nbetween frequencies was 4 Hz. The detection limit of the system, when estimated using methanol and\nethanol, was 0.1 ppm. Their linearity was in the range of 0.1 to 26,000 ppm. The power consumption\nlevels of the analog and digital circuits were 1.742 mW and 761 Ã?¼W, respectively.
Loading....