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FE are derived from forward-current amplification and common-emitter configuration respectively.įor ac conditions, an ac beta has been defined as the changes of collector current (I C) compared to the changes of base current (I B) where I C and I B are determined at the operating point. On data sheet, β dc= hfe where h is derived from ac hybrid equivalent circuit. The ratio of dc collector current (I C) to the dc base current (I B) is dc beta (β dc ) which is dc current gain where I C and I B are determined at a particular operating point, Q-point (quiescent point). There is still some value of current flowing. Small increase in I B causes big increase in I C I B(♚) is very small compared to I C (mA).

Output characteristics for common-emitter npn transistor.įor small value of V CE (V CE V CESAT, I C does not totally depend on V CE → constant I C

Increasing V CE will reduce I B for different values. I B will flow when V BE > 0.7V for silicon and 0.3V for germanium.īase-emitter junction is forward bias. I B is in microamperes compared to milliamperes of I C. Proper Biasing of common-emitter configuration in active region. input (base terminal) and output (collector terminal) parameters. Two set of characteristics are necessary to describe the behavior for CE i.e. Emitter is usually the terminal closest to or at ground potential.Īmplifier design is using connection of CE due to the high gain for current and voltage. It is called common-emitter configuration since : emitter is common or reference to both input and output terminals.

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