On Functional Modules Based on Integration of Acoustic Wave Devices and Semiconductor Circuitry

本计画旨在从多个角度探讨将RF声波元件与半导体电路整合以实现功能性RF模组的可能性。首先，研究RF声波元件对功率放大器（PA）性能的影响。结果表明，射频滤波器的阻抗Z对功率放大器的功率附加效率（PAE）有显著影响，要实现高PAE必须抑制阻抗Z的变化。还指出，谐波频率的Z对于高PAE实现也是重要的，因为在高功率操作下非线性是明显的。作为一种对策，在两个RF滤波器上附加两个90°混合器可以完全抑制Z值变化，并通过实验验证了这种方法的有效性。然后讨论了利用Cu电极/15°YX-LiNbO_3-衬底结构实现新型功能表面声波（SAW）器件。结果表明，体波辐射的影响可以通过简单地增加铜的厚度来抑制。该技术对于降低滤波器插入损耗是有效的。然后提出了使用加权虚拟电极和外涂粘性材料来抑制滤波器通带中出现的不必要的响应，并提出了将RF放大器和滤波器相结合的各种滤波器等新的功能器件，并从各个方面详细讨论了适合这些目的的器件结构。

This project was aimed at discussing possibilities of functional RF modules realized by the integration of RF acoustic wave devices and semiconductor circuitry from various aspects.First, influence of RF acoustic wave devices to the power amplifier (PA) performances was investigated. It was shown that the impedance Z of RF filters significantly influences to the power added efficiency (PAE) of PAs at high power operation, and it was pointed out that Z variation must be suppressed to realize high PAE. It was also indicated that Z for harmonic frequencies is also important for the high PAE realization because non-linearity is obvious at high power operation. As a countermeasure, it was shown that Z variation can be fully suppressed by attaching two 90° hybrids to two RF filters, and effectiveness of this approach was demonstrated experimentally.Then we discussed realization of new functional surface acoustic wave (SAW) devices by the use of Cu-electrode/15°YX-LiNbO_3-substrate configuration. It was shown that the influence of the bulk wave radiation can be suppressed by simply increasing Cu thickness. This technique is effective for the reduction of the filter insertion loss. Then use of weighted dummy electrodes and over-coating viscous materials were proposed for the suppression of unnecessary responses appeared in the filter passband.Furthermore, we proposed new various functional devices such as various filters combining RF amplifiers and filters, and device configurations appropriate for the purposes were also discussed in detail from various aspects.