The purpose of the emitter bypass capacitor in a CE BJT amplifier is to

The purpose of the emitter bypass capacitor in a CE BJT amplifier is to

Right Answer is:

Increase the mid-band voltage gain of the amplifier

SOLUTION

The purpose of the emitter bypass capacitor in a CE BJT amplifier is to increase the mid-band voltage gain of the amplifier.

  • A bypass capacitor is a capacitor that is used to establish an ac ground (or common) connection at a .specific point in a circuit.
  • The voltage gain of a common-emitter amplifier varies inversely with its total ac emitter resistance. The lower the ac resistance of the emitter circuit, the greater the voltage gain of the amplifier.
  • By effectively shorting RE. the bypass capacitor ensures that the value of RE does not weigh into the voltage gain calculation for the amplifier.

bypass capacitor in a CE BJT amplifier

  • The bypass capacitor also provides a low reactance path to the amplified a.c. signal. If it is not inserted, the amplified a.c. signal passing through RE will cause a voltage drop across it.
  • This will reduce the output voltage, reducing the gain of the amplifier.
  • When a bypass capacitor is connected in parallel with an emitter resistance, its input impedance reduces while the mid-band voltage gain of the amplifier increase.
  • Bypass capacitors also reduce both the power supply noise and the result of spikes on the supply line.
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