Research of the Balance Analysis and the Multi-Objective Design of Balanced Acoustic Wave Devices

近来，差分电路被广泛地采用在诸如蜂窝电话的移动的电信系统的RF（射频）电路中，因为它们在抗噪声和功耗方面都上级传统的非差分电路。平衡式声波器件是一种具有多个平衡端的声波器件，能有效地工作在差分电路中。然而，在平衡声波装置的设计中，必须考虑其平衡端子的信号的平衡特性。因此，传统的非平衡声波器件的优化设计方法不能直接应用于平衡声波器件的优化设计，本文提出了一种基于平衡分析的平衡声波器件优化设计方法。首先，分别提出了优化设计方法的三个核心技术：仿真技术、评价技术和优化技术。其次，将平衡式声表面波滤波器的设计问题转化为一个多目标优化问题，该滤波器是一种典型的平衡式声表面波器件。然后将遗传算法（GA）和遗传局部搜索算法（GLS）分别应用于多目标优化问题，得到一组Pareto最优解，最后通过对Pareto最优解的分析发现，通过增加优化设计中考虑的设计参数，可以同时改善平衡声波器件的两个或多个不同功能。

Recently, differential circuits are adopted widely in the RF (Radio Frequency) circuits of mobile telecommunications systems such as cellular phones, because they are superior to conventional non-differential circuits in both the noise-resistant and the power consumption. The balanced acoustic wave device is a kind of the acoustic wave device that has several balance-terminals and works effectively in differential circuits. However, in the design of the balanced acoustic wave devices, the balance characteristics of the signals of their balance-terminals have to be considered. Therefore, conventional optimum design methods of non-balanced acoustic wave devices cannot be used directly to the design of balanced acoustic wave devices.In this research, a new optimum design method of balanced acoustic wave devices based on the balance analysis has been developed. First of all, three core techniques of the optimum design method, namely, simulation technique, evaluation technique and optimization technique, were proposed respectively. Also the effectiveness of those techniques was confirmed.Next, the design of a balanced surface acoustic wave filter, which is a typical balanced acoustic wave device, was formulated as a multi-objective optimization problem. Then a genetic algorithm (GA) and an original genetic local search (GLS) were applied to the multi-objective optimization problem respectively to obtain a set of Pareto-optimum solutions.Finally, by analyzing the set of Pareto-optimum solutions, it was found that two or more different functions of the balanced acoustic wave device could be improved simultaneously by increasing the number of the design parameters considered in the optimum design.