高電子遷移率電晶體高頻參數萃取與微波模型建立

Abstract

在微波通信與個人行動通信無線網路系統蓬勃發展潮流 激勵下，微波積體電路技術與高性能多功能高速元件，已廣 泛地成為學術研發與產業需求之研究焦點。尤其單晶微波積 體電路(MMIC)設計方面，高電子遷移率電晶體(HEMT)應用 範圍大幅成長，逐漸成為射頻積體電路(RFIC)元件之關鍵技 術。 在這篇報告中，我們將要報告高電子遷移率電晶體 (HEMT)發展歷程與結構特性，應用在小訊號等效電路模型的 建立上。HEMT 最大的優點就是擁有高電荷密度的二維電子 雲及高速度的載子遷移率。由於HEMT 擁有高電子遷移率， 使得該元件的轉導值非常高，且也可改善元件的高頻特性， 所以HEMT 應用在行動電話及衛星通訊技術及軍事方面有 很大的幫助。 無線通訊技術產品是由許多被動電路所組成的高速半導 體元件。應用在無線通訊最主要的就是改善高頻特性，因此 萃取高頻參數，對於射頻積體電路模型的建立是很重要的關 鍵。 我們知道小訊號等效電路對於場效電晶體的特性分析， 如：增益、雜訊…等，是非常有幫助的，在設計微波電路及 元件的製程。我們將量測到的小訊號等效電路中元件的數 值，帶入軟體並且建立元件模型，接著調變數值使得我們所 模擬出的參數值與實際值接近，就可以成功萃取出真實的元 件數值。得到我們想要的結果並完成該報告。

With wireless communication systems moving toward larger user capacity and higher data rate and the demand for high-frequency, thus the high-performance devices are increasing on a global scale. The high-speed microwave device manufacturers for global trade are important. This category includes Metal-Semiconductor Field-Effect Transistor (MESFET), High Electron Mobility Transistor (HEMT), and Heterojunction Bipolar transistor (HBT), etc... In this term paper, we will report the HEMT historical evolution, structures, applications and high-frequency model build-up. The material properties that have the greatest impact on the high-speed performance of HEMTS are the high sheet charge density in the two-dimensional electron gas (2DEG) and the superior electron velocity. Since HEMT has high-speed electron mobility, it can result in higher transconductance (gm) and improved high-frequency characteristics. So the demands for the HEMT applied to the cell-phone, satellite communication and military have been growing tremendously. Various kinds of wireless communication technological products are formed by lots of various passive circuits, composed of high-speed semiconductor devices. The device high-frequency characteristics are essential in improving quality of the wireless communication products. Therefore, the extraction of the high-frequency parameters is the key point for the RF model build-up. Knowledge of the small-signal equivalent circuit of a field-effect transistor is very useful for the device performance analysis (gain, noise, etc.) in designing microwave circuits and characterizing the device processing. Usually, the small-signal equivalent circuit is obtained by optimizing the component values to closely fit the device measurement results of the small-signal microwave scattering parameters. Consequently, this is the main motive for working on this term project.