CAJ | 학술논문

针对融合RFID的无线湿度传感器节点设计的需求，采用中芯国际0．18μm CMOS工艺设计并制造了一种集成湿度传感器节点。该传感器节点采用湿度传感器与其它标签电路集成设计，制造成本低。湿度传感器单元采用聚酰亚胺作为感湿材料，利用顶层金属层制作叉指结构电极，无需任何后处理工艺。整流电路采用自偏置结构降低了MOS开关管的有效导通电压，避免了高成本肖特基工艺的使用。接口电路基于锁相环原理，采用全数字电容－数字直接转换结构，能够工作在超低电源电压下。后期测试结果显示，该无源湿度传感器标签在常温下灵敏度为18．75 fF／％RH，最大回滞偏差7％，整体功耗约为4μW，在阅读器发射功率为2 W条件下，最大工作距离达到14 m。
침대융합RFID적무선습도전감기절점설계적수구，채용중심국제0．18μm CMOS공예설계병제조료일충집성습도전감기절점。해전감기절점채용습도전감기여기타표첨전로집성설계，제조성본저。습도전감기단원채용취선아알작위감습재료，이용정층금속층제작차지결구전겁，무수임하후처리공예。정류전로채용자편치결구강저료MOS개관관적유효도통전압，피면료고성본초특기공예적사용。접구전로기우쇄상배원리，채용전수자전용－수자직접전환결구，능구공작재초저전원전압하。후기측시결과현시，해무원습도전감기표첨재상온하령민도위18．75 fF／％RH，최대회체편차7％，정체공모약위4μW，재열독기발사공솔위2 W조건하，최대공작거리체도14 m。
A wireless humidity sensor node integrated with RFID is presented in the paper.The proposed sensor node is fabricated in SMIC 0.18 μm CMOS process and integrated the humidity sensor with other tag blocks, the fabrication cost is low.The humidity sensor element utilizes polyimide as sensing material and fabricates the inter-digitated electrodes in top metal layer without any further post-processing.The proposed rectifier adopts self-biased architecture to reduce the turn-on voltage of the MOS switch.The sensor interface is based on Phase-Locked Loop theory, employs fully-digital architecture and achieves direct capacitance-to-digital conversion, and therefore it can work under ultra-low supply voltage.The measurements at 25℃ show that the proposed passive humidity sensor tag achieves a sensitivity of 18.75 fF%RH, the maximum hysteresis error of 7% and a total power dissipation of 4 μW, which allows a maximum operating distance of 14 m under a reader power of 2 W.