FEEDBACK AMPLIFIER ( MODIFIED)

An emitter follower circuit has hie= 1275 Ω, hfe=98, R_L= 3.3 KΩ, R_B=220 KΩ then current gain & voltage gain are _________________.respectively.

• 39.75 & 0.996 

• 45 & 1.5

• 45 & 0.996

• 39.75 & 1.5

The total harmonic distortion is reduced from 15% to 3% , when 4% negative feedback is used. The voltage gain without & with feedback are respectively.

• 150 & 20

• 100 & 33.33

• 100 & 20

• 150 & 33.33

An amplifier with mid band gain of 500 has negative feedback β= 1/100. If the upper cut off frequency without feedback is 60 K Hz then, with feedback it would becomes______.

• 10 KHz

• 12 KHz

• 300 KHz

• 360 KHz

An emitter follower is widely used in electronic instruments as__________.

• its voltage gain is very high

• its voltage gain never exceeds unity.

• its output impedance is high & input impedance is low

• its input impedance is high & output impedance is low.

An emitter follower is mainly used as_________________.

• an impedance matching device

• a power amplifier

• a follower of base signal

• voltage amplifier

Feedback in an amplifier increases the input impedance from 1 KΩ to 40 KΩ because of _____________.

• Positive feedback

• shunt-current negative feedback

• series-current negative feedback

• shunt- voltage negative feedback

The shunt derived series- fed feedback in an amplifier_________.

1. Increases its input impedance

2. increases its output impedance

3. decreases its output impedance

4. decreases its input impedance

of these statements-

• 1 & 3 are correct

• 1 & 2 are correct

• 3 & 4 are correct

• 2 & 4 are correct

The feedback in emitter follower is___________.

• 50 %

• 100 %

• 25 %

• 75 %

Emitter follower is a special case of __________.

• current series feedback

• voltage series feedback

• current shunt feedback

• voltage shunt feedback

In a common emitter amplifier, the unbypassed emitter resistance provides________.

• voltage shunt feedback

• current series feedback

• negative voltage feedback

• positive current feedback