Electrically Tunable Bandpass Filter with Integrated Carrier Suppression for UHF RFID Systems

Abstract

One of the most critical points in designing a RFID system based on the backscattering process is the limitations in the system dynamic resulting from the Tx-Rx-leakage, principally over the circulator and partly through environmental reflections. This signal can overshadow the modulated tag reply, which is generally at a maximum of only a few hundred kilohertz apart. This paper presents a novel patented hardware based solution, which combines the bandpass filtering of the operational channel required for a multi-reader environment with the suppression of the carrier leakage, leading to an improvement in the system dynamic of over 50 dB. Experimental results verifying the proposed architecture are presented. The relative bandwidth of the measured filter is under 0.03 % as compared to the center frequency of 866.5 MHz, corresponding to the European RFID band.

Experimental Implementation Of a Low Cost Full Analog Self-Jammer Canceller for UHF RFID Devices

“…1. analog approaches with the need for custom design of some key elements [6] [7] [8] [9] 2. digital approaches with the need for custom design of active cancellation systems of different complexities [10] or recurring to custom integrated designs as [11] The purpose of this work is to propose a novel full-analog self-jamming canceller scheme and verify its feasibility using off-the-shelf components and an innovative modular microwave technology, without resorting to custom design.…”

Experimental Implementation of a Low-Cost, Fully-Analog Self-Jamming Canceller for UHF RFID Devices

“…The adoption of a custom directional coupler as the coupling element has been proposed in [8], wherein it has been demonstrated that, with a proper selection of the reflection coefficient of the isolated port, it is possible to achieve a high degree of isolation, but with a receiver NF of more than 15 dB. Electrically tunable band-pass filters have been proposed in [9] in order to suppress the transmitter leakage using specialized tunable filters and an integrated downconversion and upconversion circuitry. The proposed solution requires a high degree of customization and the need for an external microcontroller with a NF of the receiver over 9 dB in a 200 kHz channel.…”