超高频射频识别无源标签芯片以及片上温度传感器的研究

发布时间：2019-01-05 06:05

【摘要】：无源超高频射频识别(UHF RFID)技术可以在非接触的条件下实现对目标对象的自动识别,是物联网的核心支撑技术之一。阅读距离远、通信速率快、适应物体高速运动等优点,是工作于超高频频段的射频识别系统相对于其它频段的射频识别技术而言所具有的优势。本文首先对UHF RFID的系统组成、工作原理进行了简单的介绍,并对正向和反向的能量与数据传输方式进行了介绍,再此基础上,通过分析计算,得出了标签芯片的功耗是限制通信距离的主要因素。然后,本文提出了一种完整的标签芯片系统方案,并分别对射频前端、模拟前端、数字基带和存储器做了详细的介绍。特别的,本文提出了一种全CMOS超高效率的阈值补偿倍压整流电路,其在可能的输入能量范围内,倍压整流电路的效率值都不低于50%。通过分析计算,结合存储器的需求,得出存储器读操作高压管控制电压是限制芯片通信距离的主要因素,在此基础上,提出了一种带有倍压功能的稳压电路,使标签的读取距离由5.1米扩展到了6.8米。当射频识别技术与传感器技术相结合时,其应用场合将会得到非常大的扩展。基于此,在分析了传统温度传感器应用于UHF RFID标签芯片中时面临的问题后,本文提出了一种适用于UHF RFID标签芯片的温度传感器,采用了双振荡器的结构,提高了传感器的鲁棒性。并且,采用了时分模式,在系统上电和命令到来之间的时间间隙进行温度检测,因此并不影响标签的通信距离。通过测试,在不影响通信距离的前提下,温度传感器在-40℃到85℃范围内,最大误差为±1.5℃。再次,考虑到通信的安全性,本文在分析了常用的几种数字方式产生随机数的方案,并总结出其缺点后,提出了两种适用于UHF RFID应用的随机数发生器。一种采用电阻的热噪声作为随机源,通过放大器,由D触发器进行采样输出。放大器采用低功耗技术,整体随机数发生器的功耗仅为800nW。另一种随机数发生器是在前文提出的温度传感器基础上,利用时钟抖动得到随机数,与温度传感器类似,采用时分模式,并不影响标签通信距离。最后,本文提出的标签芯片在中芯国际CMOS 0.18μm EEPROM 2P4M工艺下,采用多项目晶圆(MPW)的方式来实现。采用两种方式对芯片进行了详细的测试。首先,采用芯片绑定在印制版(COB)封装,标签与阅读器采用有线的方式进行连接,通过示波器对波形进行观察,给出了一些关键信号的波形。其次,采用倒装封装,模拟真实应用场景,对标签进行测试,结果显示,最远读取距离大于6.8米,最大可写入距离为1.8米,平均读取速率达到了66个/s。
[Abstract]:Passive UHF radio frequency identification (UHF RFID) technology is one of the core supporting technologies in the Internet of things (IoT), which can realize the automatic identification of the target object under the condition of non-contact. The advantages of long reading distance, fast communication rate and high speed motion of objects are the advantages of RFID system which works in UHF band compared with other RFID technology. In this paper, the system composition and working principle of UHF RFID are introduced briefly, and the forward and reverse energy and data transmission modes are introduced. It is concluded that the power consumption of the tag chip is the main factor limiting the communication distance. Then, a complete tag chip system is proposed, and the RF front-end, analog front-end, digital baseband and memory are introduced in detail. In particular, a threshold compensated double voltage rectifier circuit with full CMOS ultra-high efficiency is proposed. In the range of possible input energy, the efficiency of voltage doubling rectifier circuit is not less than 50. Through analysis and calculation, combined with the demand of memory, it is concluded that the control voltage of high voltage tube in memory read operation is the main factor limiting the communication distance of chip. On the basis of this, a voltage stabilizing circuit with voltage doubling function is proposed. Extended the read distance of the tag from 5.1 m to 6.8 m. When RFID and sensor technology are combined, the application of RFID will be greatly expanded. Based on this, after analyzing the problems of traditional temperature sensor applied in UHF RFID tag chip, this paper presents a temperature sensor suitable for UHF RFID tag chip, which adopts the structure of double oscillator. The robustness of the sensor is improved. Moreover, time division mode is used to detect the temperature between the time interval between the power supply and the arrival of the command, so the communication distance of the label is not affected. The results show that the maximum error of the temperature sensor is 卤1.5 鈩，

本文编号：2401378