A New Contactless Assembly Method for Paper Substrate Antennas and UHF RFID Chips

作者：Alimenti Federico^*; Virili Marco; Orecchini Giulia; Mezzanotte Paolo; Palazzari Valeria; Tentzeris Manos M; Roselli Luca

来源：IEEE Transactions on Microwave Theory and Techniques, 2011, 59(3): 627-637.

DOI：10.1109/TMTT.2010.2103210

• Flexible electronics
• heterogeneous integration
• ink-jet paper printed antennas
• RF identification (RFID)
• RF transformers

This paper deals with a low-cost method for the assembly of flexible substrate antennas and UHF RF identification silicon (Si) chips. Such a method exploits a magnetic coupling mechanism, thus not requiring for galvanic contacts between the Si chip and antenna itself. The magnetic coupling is established by a planar transformer, the primary and secondary windings of which are implemented on flexible substrate and Si chip, respectively. As a result, the Si chip can be assembled on the antenna with a mere placing and gluing process. First, the idea has been validated by theory. Electromagnetic simulations of a square heterogeneous transformer (1.0-mm side) show a maximum available power gain (MAG) of -0.4 dB at 868 MHz. In addition, the heterogeneous transformer is also quite tolerant with respect to misalignment between primary and secondary. An offset error of 150 mu m reduces the MAG to -0.5 dB. A sub-optimal matching strategy, exploiting a simple on-chip capacitor, is then developed for antennas with 50-Omega input impedances. Finally, the idea has been experimentally validated exploiting printed circuit board (PCB) prototypes. A PCB transformer (1.5-mm side) and a transformer rectifier (two-diode Dickson multiplier) have been fabricated and tested. Measurements indicates a MAG of -0.3 dB at 868 MHz for the transformer and the capability of the developed rectifier to supply a 220-k Omega load at 1.5 V with a -2-dBm input power.

• 出版日期2011-3