Basic Questions in Electronics Circuits - II

 

Basic Questions in Electronics Circuits - II

1. Define positive feedback?

If the feedback signal is in phase with input signal, then the net effect of the

feedback will increase the input signal given to the amplifier. This type of feedback is

said to be positive or regenerative feedback.

2. Define negative feedback?

If the feedback signal is out of phase with the input signal then the input

voltage applied to the basic amplifier is decreased and correspondingly the output is

decreased. This type of feedback is known as negative or degenerative feedback.

3. Define sensitivity?

Sensitivity is defined as the ratio of percentage change in voltage gain with

feedback to the percentage change in voltage gain without feedback.

4. What are the types of feedback?

i. Voltage-series feedback

ii. Voltage-shunt feedback

iii. Current-series feedback

iv. Current-shunt feedback

5. Define feedback?

A portion of the output signal is taken from the output of the amplifier and is

combined with the normal input signal. This is known as feedback.

7. Give an example for voltage-series feedback.

The Common collector or Emitter follower amplifier is an example for

voltage series feedback.

11. What is Oscillator circuit?

A circuit with an active device is used to produce an alternating current is called

an oscillator circuit.

15. What are the conditions for oscillation?

The total phase shift of an oscillator should be 360o. For feedback oscillator it

should satisfies Barhausen criterion.

18. What is Miller crystal oscillator? Explain its operation.

It is nothing but a Hartley oscillator its feedback Network is replaced by a crystal.

Crystal normally generate higher frequency reactance due to the miller

capacitance are in effect between the transistor terminal.

20. Define Oscillator

A circuit with an active device is used to produce an alternating current is called

an oscillator circuit.

21. What is a tuned amplifier?

The amplifier with a circuit that is capable of amplifying a signal over a narrow band of

frequencies are called tuned amplifiers.

23. What happens to the circuit above and below resonance?

Above resonance the circuit acts as capacitive and below resonance the circuit acts as

inductive.

24. What are the different coil losses?

Hysteresis loss

Copper loss

Eddy current loss

25. What is Q factor?

It is the ratio of reactance to resistance.

26. What is dissipation factor?

It is referred as the total loss within a component i.e1/Q

27. What is the classification of tuned amplifiers?

Single tuned

Double tuned

Stagger tuned

28. What is a single tuned amplifier?

An n amplifier circuit that uses a single parallel tuned circuit as a load is called single

tuned amplifier.

29. What are the advantages of tuned amplifiers?

They amplify defined frequencies.

Signal to noise ratio at output is good

They are suited for radio transmitters and receivers

30. What are the disadvantages of tuned amplifiers?

The circuit is bulky and costly

The design is complex.

They are not suited to amplify audio frequencies.

31. What is neutralization?

The effect of collector to base capacitance of the transistor is neutralized by

introducing a signal that cancels the signal coupled through collector base capacitance.

This process is called neutralization.

32. What are double tuned amplifiers?

The amplifiers having two parallel resonant circuit in its load are called double tuned

amplifiers.

33. What is a stagger tuned amplifier?

It is a circuit in which two single tuned cascaded amplifiers having certain bandwidth are

taken and their resonant frequencies are adjusted that they are separated by an amount

equal to the bandwidth of each stage. Since resonant frequencies are displaced it is called

stagger tuned amplifier.

34. What are the advantages of stagger tuned amplifier?

The advantage of stagger tuned amplifier is to have better flat, wideband characteristics.

35. What are the advantages of double tuned over single tuned?

1. Possess flatter response having steeper sides

2. Provides larger 3 db bandwidth

3. Provides large gain-bandwidth product.