表面聲波元件模型之建立與應用

The Modeling and Application of Surface Acoustic Wave Device

張景淳(Ching-Chun Chang)

指導教授 ： 鄭湘原

中原大學/工學院/電子工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500757

摘要

表面聲波元件(Surface Acoustic Wave Device)為通訊系統中重要的關鍵零組件。因其具有高波速、高機電耦合係數、低傳輸損失和溫度穩定性高的優異特性，因此高頻濾波器在通訊系統的表現上，一直難以被取代。由於其特殊的材料特性與波傳機制，使得表面聲波元件也漸漸地應用在感測領域中。表面聲波元件除了具有高性能、尺寸小、低成本及高重複製造性的特色外，配合著不同的外部讀出線路以及表面聲波元件的表面處理，可量測出溫度、濕度、壓力、位移、氣體解析…等物理訊號的改變。。
　　本論文利用石英作為壓電材料，並於其表面製作指叉換能器（Inter-digital Transducer），其指叉寬度及表面波傳遞的速度，使得表面聲波元件具有特定頻率的波傳特性。當粒子附著於表面聲波元件的表面時，會造成表面聲波元件的波速改變，進而改變頻率。本論文利用製作完成的雙埠表面聲波元件，與模擬設計的放大電路及元件等效模型，配合皮爾斯迴授式架構，設計出表面聲波振盪器，並將元件表面塗佈上有機薄膜，以物理特性質量負載效應來進行氣體的感測。其中所使用的表面聲波元件的中心頻率為156.9MHz，插入損耗為-19.855dB；完成的表面聲波振盪器中心頻率為157.070MHz，輸出功率為16.35dBm，其相位雜訊小於-96dBc/Hz @100KHz。
　　綜言之，本論文針對表面聲波氣體感測器提供了完整的理論、模型建立、電路設計、實驗探討與應用方向。首先建立一套分析表面聲波元件的理論，內容包括材料的波傳特性與指叉電極的頻率響應計算。接著利用相關高頻模擬軟體進行感測電路的設計與製作，最後將表面聲波元件與感測電路作系統整合，製作出表面聲波感測器，並進行氣體感測。

關鍵字

表面聲波元件 ； 模型化 ； 氣體感測器

並列摘要

SAW (Surface Acoustic Wave) device is an important-key component for communication system. Because it has excellent characteristic of high wave-velocity, high electrical coupling coefficient, low transmission loss and high temperature stability. So SAW device’s the performance of high frequency filter in communication is hard to be replaceable. Due to SAW device’s specific material characteristic and wave proceeding mechanism, it had already well-used in sensor application. SAW device owns high performance, small scale size, low cost and high repeatable production benefits; it also could measure physics signals of temperature, humidity, pressure, distance & the kinds of gas by different external circuits & surface treatment.
In this paper, we adopted Quartz as piezoelectric material and we manufacture inter-digital transducer on its surface. SAW device will have specific frequency wave proceeding feature base on finger width & surface wave passing velocity. When the particle attached to the surface of SAW device, it will cause the change of wave proceeding velocity & frequency. We use two-port SAW device with simulated amplifier circuit & equal-circuit model in this paper and matching with Pierce feedback structure, accomplishing SAW oscillator. The SAW oscillator would be spread with organic thin film and this could be used as gas sensor by recognizing different mass loading effect. The SAW device center frequency is 156.9MHz, loss is -19.855db: Our SAW oscillator center frequency is 157.070MHz, output power equal to 16.35dBm, and its phase noise margin less than -96dBc/Hz@100KHz.
As above, we provide complete theory, model setup, circuit design, experiment and application about SAW oscillator. First establishing a theory of SAW device analysis, including material wave proceeding and frequency response counting of finger electrode. Then using relative high frequency simulation software to try the design and production for sensor circuit. Final we combine SAW device with sensing circuit as a fully integrated system and becoming a SAW sensor and using as gas detection.

並列關鍵字

modeling ； gas sensor ； surface acoustic wave

參考文獻

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