1. The amplifier state of the transistor to meet the conditions of the emission junction is positive bias, collector junction reverse bias, no matter what kind of connection, the input voltage must be added to both ends of the emission junction, otherwise, the signal can not be added to the input end of the amplifier will not be amplified, that is, when the input current flows into the tube is either the base flow or the emission junction flow (note that the tube is in the amplified state at this time, input The current is slightly changed on the basis of the original base current or emitter current!)
2. In the common base connection of the transistor, the base is the common end of the input and output terminals, at this time, the emitter is used as an independent input electrode, the external signal current flows into the emitter, the remaining independent output electrode is the collector, and the output current flows out of the collector.
3. According to the definition of current amplification,Ai=Io\/Ii in the common-base circuit,Io is the collector current,Ii is the emitter current, so the common-base current amplification factor α=ic\/ie ic=βib,ie=ib ic=(1β)ib
则 a=b\/1 b