If the base is common to the input and output circuits, it is know as common base configuration as shown in fig. 1.
For a pnp transistor the largest current components are due to holes. Holes flow from emitter to collector and few holes flow down towards ground out of the base terminal. The current directions are shown in fig. 1.
(IE = IC + IB ).
For a forward biased junction, VEB is positive and for a reverse biased junction VCB is negative. The complete transistor can be described by the following two relations, which give the input voltage VEB and output current IC in terms of the output voltage (VCB) and input current IE.
VEB = f1(VCB, IE)
IC= f2(VCB, IE)
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