# Analog Electronics Communication July 2011

UNIT-I

1 (a) Draw the block diagram of a negative feedback amplifier.

Derive an expression-for the voltage gain of an amplifier of gain A when subjected to negative feedback with a feedback fraction B.

(b) State the merits and demerits of negative feedback amplifier .

2 (a) Discuss the effect of negative feedback on :

(i) Distortion

(ii) Output impedance

(iii) Input impedance

(b) An amplifier with current feedback has the following specifications :

hfe = 100Q; hie = 2000Q, R, = 15000Q

R2 = 5600Q, Re = 100Q and RL = 470Q

Calculate the values of voltage gain and input resistance of the amplifier with and without feedback.

UNIT-II

3 (a) Find an expression for the frequency of oscillations and condition for sustaining the oscillation in tuned collector oscillator.

(b) Describe Hartley oscillator circuit and explain its action.

4 (a) Sketch the circuit of schmitt trigger and explain its operation.

(b) What is a monostable multivibrator ? Explain its working with the help of neat waveform?

UNIT -III

5    Draw the circuit diagram of emitter follower at high frequencies.- Also explain its behaviour at high frequencies with necessary expression and parameter.

6. Determine gain bandwidth product, unity gain frequency using hybrid n model for CE configuration.                                                                                          .

UNIT-IV

7(a) Sketch 2 – input XOR function using static CMOS circuit technique, assume complementary signals are not available.

(b) Explain with neat diagram the working of a totem pole two input TTL NAND gate.

OR

(a) Explain the parameters used to characterize logic families..

(b) Write brief notes on ECL and RTL logic families.

UNIT-V

8. (a)Draw the circuit diagram of a push – pull amplifier. Explain its operation. (b)Discuss its advantages and disadvantages.

(a) Show that maximum collector efficiency of class A transformer coupled power amplifier is 50%.

(b)What do you understand by class A, B and C power amplifiers?

Define and explain the following terms as applied to power amplifiers:

(i) Collector efficiency

(ii) Power dissipation capability

(iii) Overall gain.