基于可动电荷的SiGe HBT势垒电容

Junction capacitance in the SiGe HBT based on movable charge

当SiGeHBT处于交流放大状态时,发射结空间电荷区和集电结空间电荷区存在可动电荷,因此,在考虑它们的势垒电容时,应采用微分电容.另外,集电结势垒区宽度与电流密度密切相关,依据电流密度该电容有3种情况.在SiGeHBT载流子输运基础上,建立了考虑发射势垒区载流子分布的势垒电容模型和不同电流密度下的集电结势垒电容模型.

When the SiGe HBT is in the normally amplified condition, there is more movable charge in emitter and collector space charge regions. Thus differential capacitance should be adopted when considering their junction capacitance. Additionally the width of the junction is largely related to the current density, so three cases exist according to the current density. Based on the consideration of carrier transit of the SiGe HBT, the B-E junction capacitance model related to carrier distribution and the B-C junction capacitance model under different current densities are established and analyzed.