Circuits

Amplifiers – Biasing (1)

  • Amplifier devices may be biased so that when a sinusoid is applied the device conducts (collector or drain current flows) for all or a portion of the cycle
  • Where the amplifier does not conduct for a complete cycle the missing part is restored by the flywheel effect in a parallel resonant (tank) circuit
  • Audio and signal amplifers operate in Class A where the device is biased to conduct for all of the cycle (360°); these are linear, theoretical efficiency is 50% but 25-30% is more normal