Although BJT transistors are current operated devices, a key characteristic is the signal voltage gain as an amplifier specified as:
A) $A _ { V } \cong R _ { C } / R E$
B) $A _ { V } \cong R _ { B } / R _ { E } .$
C) $\mathrm { A } _ { \mathrm { V } } \cong \mathrm { RE } / \mathrm { RC } .$
D) $\mathrm { A } _ { \mathrm { V } } \cong \mathrm { RC } / \mathrm { RB }$

Question

Quizplus · Accepted Answer

The signal voltage gain for a common-emitter amplifier in a BJT transistor is approximately equal to the load resistor (collector resistor) divided by the emitter resistor, i.e.,

\begin{equation}
A_V \cong \frac{R_C}{R_E}
\end{equation}

Option B is incorrect as it suggests using the base resistor in the calculation, which is not a part of the gain formula. Option C suggests the opposite of the correct formula, and option D suggests using the base and collector resistors in the calculation, which is also not correct for a common-emitter configuration.

Although BJT Transistors Are Current Operated Devices, a Key Characteristic AV≅RC/REA _ { V } \cong R _ { C } / R EAV​≅RC​/RE

Although BJT Transistors Are Current Operated Devices, a Key Characteristic $A _ { V } \cong R _ { C } / R E$