SAW RFID with enhanced penetration depth
Some methods to enhance penetration depth further are proposed and demonstrated. A second harmonics SPUDT, new criterion of matching and high reflectivity reflector are utilized to reduce the losses of SAW tag. The enhancement of reading system including high signal processing gain and compensate the center frequency mismatch between reader and SAW tag are achieved. Furthermore, the effect of decreasing working frequency to penetration capability is demonstrated. Mediums such as dry sandy, dry soil and water are compared in the experiments in order to get the achievable penetration depth. In conclusion, the practical penetration depth is superior to the ground penetrating radar with the same center frequency range.
SPUDT filters for the 2.45 GHz ISM band
Filters based on using single-phase, unidirectional transducers (SPUDT) consisting of /spl lambda//4 and wider electrodes are presented. The design variants exploit the significant difference between the reflectivity of short-circuited /spl lambda//4 electrodes and that of floating wide electrodes on 128/spl deg/ lithium niobate (LiNbO/sub 3/). The surface acoustic wave (SAW) devices operating at 2.45 GHz have critical dimensions of about 0.3-0.4 /spl mu/m, accessible to standard optical lithography. When matched, the fabricated SPUDT filters exhibit minimum insertion losses of 5.5-7.9 dB together with 3 dB passbands of 89-102 MHz. The majority of the insertion loss can be attributed to the attenuation on free surface and inside the grating, and to the resistivity of the electrodes.
Chip scale packaging using chip-on-flex technology
An increasing number of electronic designers, fabricators and users see Chip Scale Packaging (CSP) as a way to obtain the benefits foreseen in multichip packaging and Chip-on-Board (COB) without the problems and limitations currently associated with each. The Chip-on-Flex (COF) multichip packaging technology has been demonstrated to be applicable to single chip packages that meet chip scale packaging goals. This paper looks at the Chip-on-Flex Chip Scale technology and addresses issues including the process, structure, assembly, yields and reliability.