【作者】 车文毅；

【导师】 闵昊；

【作者基本信息】 复旦大学 ， 微电子学与固体电子学， 2010， 博士

【摘要】 射频识别是一项利用射频信号通过空间耦合实现无接触信息传递的自动识别技术。半有源标签使用电池对标签内部实现信号处理与数据存储的电路有源供电,但采用无源标签的反向散射机制实现与读写器的通信。电池在半有源标签中的使用,解决了困扰无源标签的能量瓶颈,使得半有源标签有望在识读距离和识别率性能上获得较大提升,同时,也为传感器和安全通信在标签中的实现提供了可能。本文首先借助对超高频射频识别系统物理通信机制以及信号传输方式的研究,理论地论证了半有源标签对提升识读距离和识别率起到的贡献。对于识读距离,本文将读写器正确信号检测的需求引入反向散射超高频射频识别系统的能量传输链路中,改进了计算系统识读距离的数学方法。通过分析不同设计水平下识读距离的制约因素,给出了半有源标签识读距离的上限。对于识别率,本文以超高频射频识别室内信道模型为基础,对半有源标签的识别率性能进行了定量分析。通过研究标签识读距离的概率特性,提出了安全识读距离的概念。根据上述理论分析得到的设计指标,本文接着对半有源标签芯片的设计和优化方法展开讨论。针对延长标签使用寿命和增加新功能等要求,本文研究和解决了半有源标签芯片设计中的三项关键技术。它们是兼顾高灵敏度通信和无线充电功能的整流器、低功耗高性能的唤醒电路,以及片上真随机数发生器。最后,结合上述三项芯片设计关键技术,本文在SMIC 0.18/μm EEPROM CMOS工艺下设计和实现了一款具有实时温度传感和温度日志功能的半有源超高频标签芯片。通过引入相关辅助电路,解决了传感器使用中涉及到的定时和实时温度读取的共存以及唤醒冲突等问题,实现了准恒流-恒压无线充电和电池过压保护。经测试验证,芯片的实际灵敏度为-23.7 dBm,休眠电流150 nA。更多还原

【Abstract】 RFID (Radio Frequency Identification) is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency portion of the electromagnetic spectrum to uniquely identify an object. Semi-passive tag uses the internal battery to supply its signal processing and data storage circuits, and communicate with readers by employing passive tag’s backscatter mechanism. Thanks to the battery, problems caused by power source in passive tag are solved. Therefore, semi-passive tag is hopefully capable of having better performances in read range and read range. Besides, advanced functions like sensor employment and security protocols become realizable. These qualities make semi-passive tag highly expected in applications like post management, dangerous cargo surveillance and cold chain logistics.By studying the physical mechanism and signal transmission of a UHF (Ultra High Frequency) RFID system, semi-passive tag’s improvement in read range and read rate is theoretically verified. The mathematical method for calculating the read range of a backscattered UHF tag is evolved by employing readers’ energy requirement for correct signal detection. According to different reader and tag performances, read range’s limitation factors are given. Afterward, this work uses an indoor UHF propagation channel to study the read range’s dependence on probability. Semi-passive tag’s improvement in read rate is evaluated quantitatively, and the concept of safe read range is proposed consequently.Subsequently, design and optimization methods for semi-passive tag chip are discussed. For the purpose of prolonging tag’s life cycle and employing new on-chip functions, key techniques in designing a semi-passive tag chip are studied. These techniques are realizing high communication sensitivity and wireless charge function by one rectifier, stable wake-up control with almost zero power consumption, and on-chip truly random number generation.With the aforementioned analysis and the proposed key techniques, a semi-passive UHF tag chip with temperature sensor is designed and implemented in SMIC 0.18μm EEPROM CMOS technology. Sensor application problems, such as the coexistence of real time temperature sensing with temperature log, and wake-up conflicts, are solved. Quasi-constant current-constant voltage wireless charge and overcharge protection function is realized in the chip. Measured sensitivity and sleep current is-23.7 dBm and 150 nA respectively.更多还原