晶体管发射极电流集边效应物理意义之探讨

Discussion on the Physical Meaning of the Edge Crowding Effect of Emitter Current in a Transistor

由基区电阻的自偏压引起的晶体管发射极电流集边效应，是限制晶体管承载电流能力的因素之一［１～４］。本文以发射极电流集边效应发生的程度，分为四个区域，详细探讨了归一化电位和电流密度分布的特点，指出：在Ⅰ～Ⅱ区，发射极电流集边效应不明显，晶体管承载电流能力主要由发射区面积决定；在Ⅰ～Ⅲ区，发射极电流集边效应明显，晶体管承载电流能力由发射区面积和发射区有效周长共同决定；在Ⅰ～Ⅳ区发射极电流集边效应已非常突出，晶体管承载电流能力由发射区有效周长决定。

The edge crowding effect of emitter current in a transistor caused by self bias of base resistor is one of the factors to limit its capability of loaded current.It is discussed in details in the paper that there are four regions depending upon the case occurred in the edge crowding effect of emitter current,The distributions and normalized voltage and current density,and their characters are discussed in this paper.It is pointed out that in region(Ⅰ～Ⅱ),the effect is not distinguished,its capability of loaded current is almost depending upon the area of emitter.Inregion(Ⅰ～Ⅲ),the effect is distinguished,the capability of loaded current is depending upon the area of emitter and its effctive peripheral length.In region(Ⅰ～Ⅳ),the effect is tremendous distinguished,the capability of loaded current is depending upon the effective peripheral length of emitter only.