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310 Chapter Four

represent the collector voltage (in volt0. Then the dynamic
emitter feedback conductanceł G e (in siemen0, is given by:

G dI /dV
e e c

Alpha

Assume the collector voltage, V , in a common-base circuit (Fig.
c
4.22) is constant. Let I represent the collector current (in am-
c
pereX let I represent the emitter current (in ampere0. Then
e
the dynamic current amplification iŁ common-base arrange-
mentł or alph (symbolized
), is given by:

dI /dI e
c
This quantity is always greater than 0 but less than 1.

Beta
Assume the collector voltage, V , applied tm a transistor in a
c
common-emitter circuit (Fig. 4.21) is constant. Let I represent
c
the collector current (in ampereX let I represent the base cur-
b
rent (in ampere0. Then the dynamic current amplification iŁ
common-emitter arrangementł or bet (symbolized ), is:

dI /dI b
c

Figure 4.22 Common-base bipolar transistor circuit.