Analysis of BJT and HBT power performance by Load-Pull method

本論文主要分為四個部分，第一部份是介紹BJT和HBT的基本原理；第二部分是HBT元件結構的量測和分析；第三部分是分析BJT在基極定電流以及基極定電壓，這兩種不同偏壓方式之下的功率特性和增益壓縮機制；第四個部分則是分析HBT在基極定電流以及基極定電壓，這兩種不同偏壓方式之下的功率特性。 在HBT的元件結構分析方面，我們有特別的方法可以求出元件的摻雜和厚度；在基極定電流的偏壓方面，我們觀察其基極電壓、集極電流和電流增益，來判斷BJT不同的增益壓縮機制；在基極定電壓的偏壓方面，我們可以利用平均電流增益的下降，來判斷BJT大信號增益的壓縮；此外，我們也比較了HBT在基極定電流和基極定電壓，這兩種偏壓方式之下不同的功率特性；另外，對於偏壓在相同的偏壓點，但是負載阻抗卻不同的情形也作了分析，我們發現高的負載阻抗和低的負載阻抗，會有不同的功率特性。This thesis is divided into four subjects. The first subject is the basic theory of BJT and HBT. In the second subject we analyze layer structure of HBT device. In the third subject we analyze the power performance and gain compression mechanism of BJT when it bias at constant base current and constant base voltage. In the fourth subject we analyze the power performance of HBT when it bias at constant base current and constant base voltage. For the analysis of HBT device structure, we have developed a special method to find out device doping and thickness. For constant base current, we determine the gain compression mechanism of BJT by observing base voltage, collector current and average beta. For constant base voltage, we determine the gain compression mechanism of BJT by the decreasing of average beta. Moreover, we compare the power characteristics of HBT when it bias at constant base current and constant base voltage. Furthermore, we also analyze the power performance when it bias at the same point with different load impedance. Finally, we found that different load impedance get different results.摘要(中文)………………………………………………………………….i 摘要(英文)………………………………………………………………....ii 誌謝………………………………………………………………………..iii 目錄………………………………………………………………………..iv 圖目錄…………………………………………………………………..…vi 第一章 簡介……………………………………………………………….1 第二章 基本理論………………………………………………………….3 2.1 Cut-off Frequency (FT)……………………………………………3 2.2 HBT的exponential I-V特性…………….…........………………6 2.3 HBT的Two-tone特性……………………………………....…..15 2.4 Kirk Effect………………………………………………….……21 2.5 Early Effect………………………………………………………26 2.6 Thermal Effect in HBT…………………………………………..29 第三章 InGaP/GaAs HBT的元件結構………………………………...31 3.1本章目的…………………………….……………………….….31 3.2集極和射極的doping和thickness……………………………....33 3.3基極的thickness和doping……………..………………….….....43 3.4 Ledge的厚度……………………………………...………….…48 3.5 InGaP/GaAs HBT的重要參數………………………………….53 3.6 InGaP/GaAs HBT的 …………………………………….…54 第四章 BJT的高頻功率特性…………………………………………...57 4.1 BJT基極定電流的增益壓縮機制…….……………..……….…57 4.2 BJT基極定電流的短軸量測結果……………..………….….…76 4.3 BJT基極定電壓的增益壓縮機制……………………..……..…93 4.4 BJT基極定電壓的短軸量測結果…………..…………………102 第五章 HBT的高頻功率特性…………………..…………………..…111 5.1 HBT基極定電壓以及定電流的分析………………………….111 5.2 HBT基極定電壓的短軸量測結果………………………..…..124 第六章 結論……………………………………………………...……..135 參考文獻…………………………………………………………...……137 Appendix A…………………………………………..……….………....139 Appendix B…………………………………………..……………….....142 Appendix C…………………………………………..…….………...….14