Rajasthan Technical University 2011-2nd Sem B.Tech Computer Science and Engineering I (Main & Back),- , Electronic Devices & Circuits (3CS2) - Question Paper

n r o Roll No. * fTotal No. of Pases I 3 I B.Tech. Illrd Semester ( Common foi Electroni 3E2072 Main/Back r Compute] c Devices & l) Examination, Feb. - 2011 r Engg. & IT t Circuits

Time : 3 Hours    Maximum Marks : 80 Min. Passing Marks : 24

Instructions to Candidates:

Attempt overall five questions, selecting one question from each unit. Schematic diagrams must be shown wherever necessary. Any data you feel missing may suitably be assumed and stated clearly.

Unit-I

1. a) What do you understand by clamping circuit with neat diagram explain the action of

i)    Positive clamming and

ii)    Negative clamper

b) Describe the Hall effect? What properties of a semiconductor are determined From a Hall effect experiment?    (8+8)

2. a) Find the output of a clipper as shown in Fig. (i). Assume that V_f = 0 and r = 0 for both diode

R,

3.    a) Find out the expression of S, S' and S' for Potential divider biasing circuit

(For C.E. configuration)

b) Draw and explain Ebers Molls representation of BJT? Also define the voltage and current used in Ebers Molls Equation for PNP transition.    (8+8)

4.    a) Draw the circuit of transistor in common emitter configuration of BJT and

sketch the output characteristics indicate the active, saturation and cutoff

region. Derive the relationship between a and j3 for BJT?

b) h - parameter for CE amplifier has h._e = 1100Q h_fe = 50, h_oe = 25* 1 O'⁶Mho, h_re = 2.5* 10 if R_l = iKH Determine the following parameters

i)    current gain

ii)    voltage gain

iii)    power gain

iv)    input impedance    (8+8)

Unit-III

5.    a) Draw the R-C coupled amplifier circuit? Calculate the current gain for low,

middle and high frequencies region?

b) The amplifier of Fig. (2) Utilizes an N-channel FET for which V_p - -2V, g_mo - 1,60 mA/V and I_DSS = 1.65mA, It is desired to bias the circuit at I_n = 0.8 mA using V_DD = 24V assume r_d R_d Determine

*)

ii)

iii)

iv) -M

such that the voltage gain is atleast 20 dB with R_s bypassed with a very large

capacitance C

C.

a)    Explain the working of n-channel MOSFET. What is the difference between enhancement and depletion mode of operation.

b)    Explain Millers theorem. Define Boot strapping with its electrical equivalent circuit?    (8+8)

Unit-IV

a)    Explain the Brakhausen criterion for sustained oscillations.

b)    Prove that in a negative Feedback amplifier

dAF	_ l		dA
A	|1 + 0A		A

Where A_p = gain with feedback, A = transfer gain, p = feedback factor.

(8+8)

8.    a) Draw the circuit diagram of voltage shunt Feedback amplifier with its necessary

effects? What are the difference between voltage shunt and voltage series Feedback amplifier?

b) Determine the operating frequency of a Hartley oscillator if L, = lOOiH L₂ = ImH mutual inductance between coils M = 10/v H and C = 10 PF

(8+8)

Unit-V

9.    a) Draw the circuit of the wein bridge oscillator. Derive the expression for

frequency of oscillation for such as oscillator

b) The parameter of a crystal oscillator equivalent circuit are L_s = 0.8 H, C_s = .08 PF R_s = 5 KQ and C_p = 1.9PF Determine the resonance frequencies F_sand F_P    (8+8)

10.    a) With the help of circuit diagram explain the working of Astable multivibrator

give its waveform what are the basic difference among the three types of multivibrator circuits

b) Draw the circuit of a Schmitt Trigger using BJT and explain its working with input voltage versus the output voltage curve.    (8+8)

3E2072    (3)

Attachment: rajasthan-technical-university-2011-b-tech-computer-science-and-engineering-36494-1.pdf

Earning:   Approval pending.