Abstract

In this paper, the deviation tolerance for the backlink frequency of 320kHz and 640kHz for eighth-order Active-R bandpass Biquadratic filter to be used for UHF RFID Systems was investigated. The filter was designed with center frequencies of F_o=320 kHz and F_o=640 kHz at a quality factor of Q=30. The simulated response characteristics show that both filters have their mid band gains decreasing with each section (stage), in the range of −0.191dB to −3.673dB for F_o=320 kHz while F_o=640 kHz had from −1.433dB to −8.820dB. The bandwidths also decreased monotonically from 8.820 kHz to 4.478 kHz at F_o=320 kHz and 16.206 kHz to 8.820 kHz at F_o=640 kHz. Results also showed that there was a very slight shift from the center frequency with deviation ranging from −0.938% to −1.116% at F_o=320 kHz and −0.969% to −0.936% at F_o=640 kHz. From the results, the filter frequency deviation is within that specified by EPC Standard of ±22%. Therefore, the filter can be used for UHFRFID Systems.