Application of Butterworth Low Pass Filter in UHF RFID Reader

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.