Class A Power amplifiers(series fed)

Class A Power amplifiers(series fed)

An amplifier is of type class A if its output remain in the active region during a complete cycle of sine wave input signal .It is an amplifier under normal condition i.e the output never saturates or cut off.If the input is 360°,then output is also 360° ,i.e distortion is very low

Efficiency

$V_{pp}=V_{cc}$
$I_{pp}=\frac{V_{cc}}{R_c}$ 
$I_c=\frac{V_{cc}}{2R_c}$
$η =\frac{V_{pp}I_{pp}}{8V_{cc}I_c}$
$=\frac{V_{cc}\frac{V_{cc}}{R_c}}{8V_{cc}\frac{V_{cc}}{2R_c}}$ 
$=\frac{1}{4}$=25%
η is low .So class A is never used as a power amplifier