A miniaturized 3 x 3-mm SAW antenna duplexer for the US-PCS band with temperature-compensated LiTaO/sub 3//sapphire substrate

Recent development of temperature compensated SAW Devices

“…When a stiff material with small CTE is chosen as the base substrate, the bonding suppresses the thermal expansion of the top surface where SAW propagates. Various bonding technologies such as fusion [20][21][22]28], room temperature [25][26][27][28] and adhesive [23,30,31] ones, have been investigated. Although the adhesive one seems most cost-effective, it is not clear whether the adhesive is stable during and after the device fabrication.…”

“…As the base-substrate, Si [21][22][23]28,30,31], glass (fused quartz) [21][22][23][24][29][30][31], and sapphire [25][26][27] have been tested. Sapphire is most appropriate for the TCF improvement, but expensive.…”

“…In contrast, usual materials including LN and LT become soft with T, and their intrinsic TCE and TCV are negative [19,20]. Another strategy is use of the wafer bonding of a single crystal LN/LT with a stiff substrate with small CTE [21][22][23][24][25][26][27][28][29][30][31].…”

Multilayered Structure as a Novel Material for Surface Acoustic Wave Devices: Physical Insight

“…The bonding technology (Eda et al, 2000) provides excellent contact between the two materials and allows fabrication of SAW devices with reproducible characteristics on a thin LN or LT plate bonded to a thick silicon or glass wafer. In these structures, high values of electromechanical coupling coefficients typical for LN and LT are combined with improved TCFs, due to low thermal expansion coefficients (TCE) determined by massive silicon, glass or sapphire wafer (Tsutsumi et al, 2004). An example of bonded wafer will be numerically investigated in section 4.…”

A miniatuirized FBAR duplexer with reduced acoustic loss for the W-CDMA applicaion

“…We have developed high-performance SAW duplexers for the US-PCS application [6][7][8] and these duplexers have been commercially accepted. However, we have selected the FBAR technology for the W-CDMA application because of the following two reasons.…”