Bipolar Junction Transistor (BJT) Circuits

$α_{dc} = {β_{dc}}/{a + β_{dc}}$

$β = {α}/{1 – α}$

$β_{dc} = I_C/I_B$

$I_{CEO} = (1 + β_{dc}) I_{CBO}$
$I_{CEO}$ = reverse saturation current

$I_E = I_B + I_C$

$γ = I_E/I_B = (1 + β_{dc})$

Current gain, $A_I = I_o/I_i$
Voltage gain, $A_v = V_o/V_i$
Power gain, $A_p = A_v$ x $A_I$

$V_i = {R_i}/{R_i + R_s}$ x $V_s$