f_（max）─载流子迁移率关系在高频HBT设计中的意义

Significance of f_(max)-Carrier Mobility Relationship in High-Frequency HBT Design

在导出ＨＢＴ的最高振荡频率与载流子迁移率关系的基础上［１］，指出了多子在影响频率性能方面与少子同样重要，呈现的几何平均关系清楚地揭示出晶体管的“双极”工作原理。在比较Ｎｐｎ和ＰｎｐＨＢＴ的频率性能中给出了目前少子迁移率的选择方法。为了提高计算的正确性，提出应进行深入的少子迁移率测量研究，以能为计算提供系统的、可靠的实验数据。初步估算得出ＰｕｐＨＢＴ的ｆ（ｍａｘ）稍高于或等于Ｎｐｎ的ｆ（ｍａｘ），最后，根据最高振荡频率与载流子迁移率的关系，对高频ＨＢＴ的最佳设计进行了比较系统的分析。

n the paper,on the basis of deduction of relationship between the maximum oscillating frequency fmax and carrier mobility, it is indicated that for the frequency characteristic the majority carrier has the same significance as the minority carrier. The relationship that fmax is proportional to the square root of the product of minority carrier mobility and majority carrier mobility shows clearly the 'bipolar' principle of transistors. By comparing the frequency performance of Npn and Pup HBT,selective method of minority carrier mobility is suggested. However, for increasing calculation correctness some studies on minority mobility measurements are needed to offer systematic and reliable experimental data. We have concluded that fmax of Pup HBT is equal to or higher than that of Npn. Finally, according to the relationship between the fine. and carrier mobility, the optimum design of high frequency HBT is analyzed systematically.