The Design Of Surface Acoustic Wave Devices And Research Of Test Apparatus

Surface acoustic wave(SAW) device are passive, the small size and easy to integrate, thus it has been used widely in the mobile communications, the radio, the television and other fields. However, because there is not mature software for the design of the SAW device, the device design has some problems, such as the long period, the great intensity and the error-prone. In addition, the SAW device is vulnerable to the influence from the external environment in the test, such as the changes of the temperature and the humidity. Hence, it is very important to design a stable and controllable independent environment to realize the accurate parameters measurement of SAW device. In order to solve these two problems, the design software and test apparatus of SAW device were researched in this paper.In the study of SAW devices design, by means of the numerical calculation function and GUI data visualization technology of MATLAB, the design software of SAW device is developed, which consists of the layout and data extraction of SAW device. When the users input parameters in the GUI interface, such as the substrate material and the center frequency,the device layout can be outputted shown immediately. Meanwhile, the coordinate data of device can be extracted from MATLAB result and displayed in the GUI interface. At last, the feasibility of the software is illustrated by design the layout and date output of a typical SAW device with the center frequency at 101.079 MHz and 32 pairs IDT.In the study of test apparatus of SAW device, a separate test apparatus is set up to meet the requirements of device test. The test apparatus consists of an independent test room and the temperature control, the mixed gas acceleration and extension of liquid into gas module placed in the test room. The PID algorithm is used in the temperature module to control PWM pulse output, and then, to control the way temperature module work. In conclusion, a stable environment is provided in the test apparatus, which realizes functions of the temperature real-time control, the gas-mixed acceleration, and the liquid-gas conversion without assistive apparatus, etc.