本論文主要研究如何增進雙載子電晶體元件(BJT)的模擬效率。在傳統的方式上,以二維空間模擬雙載子電晶體須要龐大的資料量和計算量,尤其是在混階(mixed-level)模擬應用上,往往有大量的主動元件。有鑑於此,我們將發展一維空間上的雙載子電晶體模擬來取代二維空間上的模擬。本論文著重研究一維空間上的模擬方法,並發展新的類似一維空間的模擬方式克服一維空間模擬上的缺點。在論文內所用的模擬方式為等效電路法(equivalent circuit approach),等效電路法將柏松方程式和電子電洞連續方程式轉換成等效電路,在混階電路的模擬上有廣泛的應用。在混階電路模擬上,以本論文所發展的一維空間元件取代二維空間元件的模擬將有助於節省計算時間、存取資料量以及程式的維護。而新的類似一維空間的模擬方式可以有效的解決一維空間模擬的缺點,使模擬結果更接近二維空間的模擬,並且不大量增加模擬的計算量。藉由此類似一維空間的模擬方式的發展,可以將其應用到其他適合的二維元件模擬,增進模擬的效率。 This thesis studies on enhancing the efficiency of simulation in bipolar transistor. A new one-dimensional simulation will substitute conventional two-dimensional simulation in bipolar transistor. Some new numerical method will be presented in this thesis. The fundamental method of device simulation is equivalent circuit approach. In such an approach, Poisson's equation and continuity equations are formulated into a subcircuit format suitable for general circuit simulators. This numerical method is applied well to mixed-level device and circuit simulations. In order to enhance the efficiency of mixed-level simulation, the substitute one-dimensional simulation is developed. This one-dimensional simulation is more convenient and powerful than two-dimensional simulation. Then, another new quasi-one-dimensional bipolar transistor modeling will improve the practicability and accuracy of device simulations. According to the technique of one- and quasi-one dimensional simulation in bipolar transistors, it is helpful for large mixed-level circuit simulation and design.