Smaller Surface Acoustic Wave Duplexer for US Personal Communication Service Having Good Temperature Characteristics

Abstract

Using a flattened SiO2/Cu electrode/36–48° LiTaO3 structure, a small (5×5 mm2) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US personal communication services (PCS) was realized by the authors. However, a smaller duplexer is strongly required. Using the flip-chip bonding process of SAW chips and a Rayleigh SAW propagating on a flattened SiO2/Cu electrode/126–128° YX-LiNbO3 structure, which has a larger coupling factor than the above-mentioned substrate, a smaller (3×2.5 mm2) SAW duplexer with a good TCF was realized.

Model parameter extraction of lateral propagating surface acoustic waves with coupling on SiO2/grating/LiNbO3structure

“…[1][2][3][4][5][6][7][8][9][10][11] One of these SAWs generates spurious resonances, and their complete suppression is mandatory. The authors pointed out that coupling between two SAWs plays an important role for the suppression.…”

Suppression of transverse-mode spurious responses for zero temperature coefficient of frequency SAW resonator on a SiO<inf>2</inf>/Al/LiNbO<inf>3</inf> structure

“…So, small TCF is also required in addition to moderate K 2 more than 7% to realize SAW duplexers for these systems. Recently, several device configurations have been examined and reported for the application; a conventional SiO 2 /Al/LiTaO 3 structure [1], a [6], and a wafer-bonded LiTaO 3 /sapphire substrate [7]. Moreover, the authors reported that the SAW resonator with a moderate K 2 , a zero TCF, and no Rayleigh-mode spurious response could be realized by optimizing the SiO 2 shape above the IDT and the SiO 2 thickness on a SiO 2 /Al/LiNbO 3 structure [8].…”

6E-5 High Performance and Miniature Surface Acoustic Wave Devices with Excellent Temperature Stability Using High Density Metal Electrodes

“…To realize them, SAW substrates combining a high density metal electrode and a piezoelectric substrate have been investigated. The author has succeeded in exciting various SAWs having large electromechanical coupling factor, large reflection coefficient, and excellent temperature stability, by combining high density metal electrode such as tantalum (Ta), copper (Cu), and gold (Au) and the various substrates [2][3] [4][5] [6] [7][8] [9][10] [11] [12].By applying their features, following various miniature SAW devices such as IF filters, duplexers, and RF filters with good temperature stability and good frequency characteristics were developed.…”

“…(2-2) Smaller duplexer for US-PCS using flip-chip bonding technique than above mentioned flattened-SiO 2 /Cu-electrode/36∼48 • LiTaO 3 and flattened-SiO 2 /Cuelectrode/126∼128 • YX-LiNbO 3 [9].…”

“…SAW resonator properties of SiO 2 /Cu electrode/LiTaO 3 and SiO 2 /Cu electrode/LiNbO 3 structures[9].…”