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.
- 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.