VLSI与电子器件教学资料：Chapter 7 Bipolar Junction Transistor双极结型晶体管.pptVIP

Once the minority carriers reach at the edge of transition regions, they will diffusion and produce a distribution δp in the base . The hole distribution in base region is different from that in a p-n junction. Diffusion equation: Boundary conditions: For collector junction strong reverse-biased, ?pC?-pn, and pn is ignored （ ?pC?0） For collector junction strong reverse-biased, ?pC?-pn, and pn is ignored （ ?pC?0） Now the hole concentration is obtained, how to evaluate the emitter and collector currents? 7.4.2 Evaluation of the terminal currents Diffusion currents equations with Where, Example 7-2 Find the expression for the current I for the transistor connection shown if γ=1. How does the current I divide between the base lead and the collector lead? P+ P+ n C E B I V + - Solutions: Since VCB=0, p-n junction back * * Chapter 7 : Bipolar Junction Transistor(双极结型晶体管) Bipolar transistor 双极晶体管 emitter junction 发射结 collector junction 收集结 base 基区 transit time 渡越时间 common base 共基极 lifetime 寿命 excess hole 非平衡空穴 diffusion length 扩散长度 injection 注入 generation-recombination 产生-复合 emitter injection efficiency 发射极注入效率 current transfer ratio电流转移比 the common-base current gain共基极电流增益 the common-emitter current gain共发射极电流增益 amplification factor放大因子 Summary about Bipolar Junction Transistor (BJT) Transistor=?+? Transistor is the Combination of the words “transfer” and “resistor”. Summary about Bipolar Junction Transistor (BJT) (1) input characteristics Characteristics of BJT Common-base, IE~VEB Common-emitter, IB~VEB (2) Output Characteristics Common-base, IC~VCB VCB0, i.e. the collector junction is positive biased.At some point,Ic=0 saturation VEB=0 Cut-off Common-emitter, IC~VCE VCB-kT/q VCB=0, saturation IB=0, Cut off We will use the p-n-p transistor for most illustration. The main advantage of the p-n-p for discussing transistor action is that hole flow and current are in the same direction. Once these basic ideas are estab