UHF RFID system is applied in the product traceability, storage management, transportation and other occasions with the advantages of a far communication distance and rapid rate of reading. Low pass filter circuit is one of the most important parts in UHF RFID reader, so its design performance may affect the system communication. According to the filter's requirements in UHF RFID reader, this paper designs a 5 order Butterworth low pass filter whose band pass cutoff frequency of 8 MHz and stop-band cut-off frequency of 15 MHz (more than 25 dB attenuation). The result shows that the pass-band with about 3 dB attenuation quantity, 15 MHz place more than 25 dB attenuation (about 27 dB), and increases the accuracy of the signal to read because the pass-band with no ripple ups and downs. The Butterworth low pass filter meets the design requirements of the system.%UHF RFID系统因通信距离远、读写速率快等优势广泛用于产品溯源、仓储管理、交通运输等多种场合,低通滤波电路作为超高频读写器的重要组成部分之一,其设计性能的优劣直接影响系统的通信性能.本文针对超高频读写器滤波电路的要求,设计了5阶巴特沃斯低通滤波器,其通带及阻带的截止频率分别为8MHz、15MHz(阻带衰减量大于25dB).结果表明,该低通滤波器通带内其幅值衰减量低于3 dB,阻带的截止频率处其幅值衰减量大于25dB(约27dB),满足了系统设计要求,且通带内无波纹起伏,增大了信号读取的准确性.
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