How do you put a BJT into the active region? Solution About BJT: Bipolar junction transistor consists of two p-n junctions. Those are, the Emitter-Base Junction and the Collector-Base Junction. Based on junctions conditions BJT will operates in three different modes/regions. Those are When VCB is reaches maximum value of fixing emitter current, the collect current is remains constant for further increase of VCB. When collector current is equal to the emitter current it enter to the active region..