362 SEMICONDUCTOR DEVICES
7.3.8(c)ICEOmay often be ignored at room temperature, in which case the model reduces to an
open circuit at all three terminals. Representative values for a silicon BJT at room temperature
areVγ(junction threshold voltage)=0.7 V,Vsat= 0 .2 V, andICEO= 0 .001 mA. The one BJT
parameter that must be specified is the common-emitter current gainβ, because it is subject to
considerable variation.
Figure 7.3.3Common-base static curves for typicalnpnsilicon BJT.(a)Emitter (input) characteristics.(b)
Collector (output) characteristics.
V
Figure 7.3.4Common-emitter static curves for typicalnpnsilicon BJT.(a)Input characteristics.(b)Output
characteristics.