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Abstract:
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Radio-frequency identification (RFID) has been successfully used in many applications including object identification, logistics, localization and it has also been considered as an enabling technology for the Internet of things. Both the reader and the tag of the RFID system have a resonating network that enables data and energy communication. However, a mistuning of these resonating networks can either reduce reading range or lead to a disposal of the tag. Hence, to solve this problem we propose novel LC tuning systems that can be integrated on an RFID chip to automatically tune the tag. It is possible to automatically tune LC networks using a Q-enhanced technique as the core of the analog tuning system. In this regard, one LC tuner based on negative resistances is described in the thesis. It is also described a tuner based on a sample of the RF limiter current used in RFID tags. It is possible to say that these tuners complement each other in the sense that the former system tunes its resonating network based on voltages, while the latter tunes its LC network based on currents. It is also feasible to tune resonating circuits when its step response is analyzed. So we propose in this thesis another circuit that can measure the Q of its resonating network and also how close it is from the resonating frequency. This system digitally reports these parameters and it can also be used used in filters. The systems are designed using a 130-nm CMOS process and they occupy an area smaller than 0.035mm2, making the presented prototypes suitable for integration on an RFID chip. Along the thesis we see that the two tuners operate at 125 kHz and the LC parameter extractor operates at 900MHz. |
