Implementation and Performance Analysis of Eigth-Order Active-R Biquadratic Bandpass Filter for Potential Use in UHF RFID Applications

In this paper, a functioning bandpass filter designed, simulated and implemented for potential use in the front-end framework of the Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) receiver is presented. The RFID communications in the UHF domain operate in the frequency range from 860 to 960 MHz as such many other communication systems that utilize frequencies within this range may interfere in the RFID communication. To avoid this interference and eliminate any noise beside the operating bandwidth a Bandpass filter is inserted in the first block of the RFID receiver. The architecture that was used to implement the Eighth-order Active-R Band pass filter is the Biquadratic topology. The filter was first designed using the Second-order active- R Band pass filter (stage 1), with centre frequencies of f0=40 kHz, 107 kHz, 160 kHz, 256 kHz, 320 kHz, 465 kHz, and 640 kHz and variable quality factors of Q=25 and 30. Choosing =0.1, R1a=1.0x106, R2=40x103, the values of other Resistors were calculated. To realize an Eighth-order configuration, the second-order filter already designed was cascaded in four stages and implemented using Multisim electronic workbench version 11.0 software. The results obtained and presented shows that the Active-R bandpass filter using biquadratic topology at Q = 30 worked well and better as specified in the filter theory and EPC Global Class 1 Generation 2 protocol. This filter is characterized by low gain, bandwidth is in good agreement with filter theory and the roll-off rate is very good, which gave an eighth-order active filter.