因為異質接面電晶體 (HBT) 擁有高電流處理能力、高截止頻率與高最大震盪頻率，故其被廣泛地應用在微波電路上。其中，對設計功率放大器者而言，最大的阻礙即是自發熱效應的問題，而自發熱效應將減低元件之特性，嚴重的話將產生熱跑脫現象(thermal runaway)，進而將元件燒毀。通常使用射極分佈電指的結構和外接壓艙電阻以穩定熱效應對元件的影響。所以本報告將針對兩種方向去加以討論和分析: (1) 在相同的射極總面積與壓艙電阻下，不同的射極長度對熱的影響。(2) 在相同的異質接面雙極性電晶體的大小下，不同的壓艙電阻值對熱的影響。 本論文中，亦利用一套簡單萃取最佳化壓艙電阻之理論與方法，並成功的利用此最佳化壓艙電阻值模擬出最佳化後的I-V曲線圖。 此外，本論文中亦提出一溫度補償電路，其應用在電路上將使得其功率元件特性變好。而此電路當模擬在操作環境溫度變化範圍在-450C~850C時亦或是偏壓電路供給電壓變動範圍在2.6V~3.2V，其模擬之結果皆可達到增益固定之功能。 Because Heterojunction Bipolar Transistors has the characteristics of high current handling capability, high cutoff frequency and high maximum frequency for oscillation, HBT have been widely accepted by the microwave engineering as an excellent candidate for many high-frequencies applications. A major obstacle for the employment of HBT for high power and high frequency applications is self-heating effect, which is even more serious with the downscaling of the chip .The self-heating effects degenerate the electrical characteristics of transistors leading to DC bias shifting and the thermal runaway. To avoid the thermal runaway phenomenon, we usually use multi-finger or ballastinging resistor. We want to discuss in view of two kinds of sides: (1) same device emitter area 、ballastinging resistor and different emitter length to thermal stable (2) same device area and different ballastinging resistor to thermal stable. We induce the ballastinginging resistor in this thesis. The optimized ballastinginging resistor which built in the HBT in series can eliminate the thermal instability and improve RF performance. Therefore, we design the temperature-compensation bias circuits to further improve the performance with a wide temperature range operating from -450C to 850C. Additionally, the designed circuits also can achieve the low variations for RF characteristic under the bias voltage ranging from 2.6V to 3.2V.
