1.a. What is the source of the leakage current in a transistor?

If the emitter current of a transistor is 8 mA and $I_{B}$ is 1/100 of $I_{C}$, determine the levels of $I_{C}$ and $I_{B}$.

1.b. Explain the concept of virtual ground in operational amplifiers.

1.c. Draw the spectrum of amplitude modulated wave and explain its components.

1.d. Explain adaptive delta modulation.

2.a. The emitter bias configuration as shown in following figure has the specifications:

$.I_{CQ} = \frac{1}{4}I_{Csat}$ $.I_{Csat} = 8 mA$

$V_{C} = 18 V$ and $\small \beta$ = 110

Determine $R_{C}$, $R_{E}$ and $R_{B}$

2.b. Explain the following parameters and their values for 741 op-amp

CMRR, slew rate, Gain Bandwidth Product, Input Offset Voltage and Output Resistance.

3.a. GIven $\small \beta$ = 120 and $I_{E}$ = 3.2 mA for a common-emitter configuration with $r_{0} = \small \ \infty\small \Omega$, determine

i) $Z_{i}$

ii) $A_{v}$ if a load of 2 k$\small \Omega$ is applied.

iii) $A_{i}$ with the 2k$\small \Omega$ load.

3.b. State and explain Barkhausens criteria for oscillations.

3.c. Explain principle of TDM.

3.d. Determine the output voltage for the circuit if $V_{1}$ = 5V and $V_{2}$ = 3V

4.a. Draw the block diagram of phase cancelleation SSB generation and explain how the carrier and unwanted sidebands are suppressed.

4.b. Draw the PAM, PPM and PWM waveforms in time domain assuming a sinusoidal modulating signal. Explain them in brief.

5.a. State shannon's thorem on channel capacity.

What is the maximum capacity of a perfectly noiseless channel whose bandwidth is 120 Hz, in which the values of the data transmitted may be indicated by any one of the 10 different signal, explain them in brief.

5.b. With repect to neat diagram explain the elements of analog communication system.

6.a. What is Nyquist Criteria? What is its significance?

6.b. Give the proper definition for entropy and information rate.

6.c. Write short note on op-amp as comparator.

6.d. Differentiate between Class A and Class C power amplifiers with respect to circuit diagram , operating cycle and power efficiency.