【作者】 徐鑫；

【导师】 谢甫珍；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2015， 硕士

【摘要】 超高频射频识别技术由于传输速率快、存储容量大、读写范围大等优点被广泛应用在各种服务行业中,本文旨在研究并设计CMOS单芯片UHF RFID读写器中的模拟基带滤波器,所得的研究成果如下所示:1、研究了多种实现模拟滤波器的方法以及各自的优缺点,针对UHF RFID零中频接收机对模拟基带的要求,设计了一款截止频率在84kHz~1.55MHz之间可调的信道选择滤波器,考虑到线性度及衰减度的要求,采用四阶全差分切比雪夫Tow-Thomas滤波器结构。由于接收机信道选择滤波器对截止频率精确度要求很高,因此本文设计了一款结构简单且精度高的自动频率校准电路。在TSMC 0.18μm CMOS混合信号工艺的基础上完成电路与版图设计,后仿真结果显示滤波器带宽在86.27kHz、168.6kHz、354.8kHz、448.4kHz、579.7kHz、684.3kHz、714.3kHz、1.59MHz八种频率之间可调,线性度指标带外IIP3达到31.14dBm。2、为满足接收机模拟基带电压增益的要求,设计了一款可编程增益放大器PGA,电压增益范围达到58dB。零中频接收机需要考虑直流偏移对电路的影响,因此在PGA电路中增加了直流偏移消除电路。后仿结果显示PGA电路实现带内电压增益在0~58dB范围内可调,步进2dB,误差小于0.5dB,直流附近衰减达到-40dB,带内IIP3为27.83dBm。3、针对UHF RFID直接变频发射机对模拟基带的要求,设计了一款五阶切比雪夫低通滤波器,以抑制由前级电路DAC产生的镜像频谱干扰。并且在滤波器上通过电阻阵列实现增益可调,以调节DAC输出信号幅度。后仿结果显示滤波器-3dB带宽为613.8KHz,在DAC镜像干扰频率6.5MHz附近带外抑制达到116dB,带内电压增益在-8~0dB范围内可调,步进0.5dB,误差小于0.1dB。更多还原

【Abstract】 UHF RFID technology has been widely used in many kinds of service industries,on account of its advantages of fast transferring rates,large storage capacity and long distance reading. This paper aims to study and design the analog baseband filter for CMOS single-chip UHF RFID Reader.The results of the research are as follows:Firstly,a variety of methods to design analog filter are studied and compared. To meet the requirements of analog baseband for UHF RFID Zero IF receiver,this paper design a channel selection filter whose cutoff frequency is adjustable from 84 kHz to 1.55 MHz. Taking into account the requirements of linearity and attenuation,the filter employ fourth-order fully differential chebyshev Tow-Thomas structure. Because the channel selection filter’s cutoff frequency needs very high accuracy,this paper designs an automatic frequency calibration circuit which presents simple structure and high accuracy. On the base of TSMC 0.18μm CMOS mixed-signal process,this paper accomplishes the design of the circuit and layout. The post simulation results display that the filter’s cutoff frequency can be set in eight different frequencies: 86.27kHz、168.6kHz、354.8kHz、448.4kHz、579.7kHz、684.3kHz、714.3kHz、1.59 MHz,and the out of band IIP3 achieves 31.14 dBm.Secondly, to meet the requirement of voltage gain of the receiver analog baseband, this paper design a Programmable Gain Amplifier(PGA) which can obtain a voltage gain range of 58 dB. Because of the existence of DC offset in Zero IF receiver,the Dc Offset Cancellation circuit must be applied in the PGA. The results of post-layout simulation show that the PGA’s voltage gain can vary from 0 to 58 dB by a gain step of 2dB and gain error less than 0.5dB;It achieves-40 dB attenuation near DC and the in band IIP3 achieves 27.83 dBm.Thirdly,this paper designs a fifth-order chebyshev low-pass filter to meet the requirements of analog baseband for UHF RFID direct conversion transmitter. The filter is used to suppress the mirroring spectrum interference generated by the former circuit DAC. The voltage gain of the filter is obtained by controlling the resistor array to adjust the signal amplitude of DAC output. The results of post-layout simulation show that the filter’s-3dB bandwidth is 613.8KHz,and the out of band rejection of image frequency interference near 6.5MHz reaches 116 dB.The filter’s voltage gain can vary from 0 to-8dB by a gain step of 0.5dB and gain error less than 0.1dB.更多还原