**Campus Recruitment – Technical Interview – Electronics and Communication Engineering**

Contents

** Electronics and Communication Engineering**

1) Define band-gap energy. What is the relation between Eg and temperature?

2) What is Fermi-Dirac function?

3) Define mean life time of a carrier: hole or electron.

4) What is continuity equation?

5) Can you mention any one application of Hall Effect?

6) Define hole in a semi conductor.

7) Write down the expression for current in a p-n junction diode.

8) What are transition and diffusion capacitances of a p-n diode?

9) What is the difference between static and dynamic resistance of a diode?

10) What is the specialty of Zenere diode?

11) What is the application of tunnel diode?

12)What is ripple factor?

13)Mention ripple factor and regulation of: Half wave rectifier; Full wave rectifier; Bridge rectifier C – filter PI filter.

14)is meant by regulation in a power supply?

15) What is clipper?

16) What is clamper?

17) What is Ebers-Moll equation of a transistor?

18) What are the different regions of operations of a transistor?

19) What are the different configurations of transistor?

20) Why does a transistor need biasing?

21) Define stability factor.

22) Mention the merits and demerits of various bias circuits.

23) What is thermal runaway?

24) Define H – Parameter model of transistor.

25) What is small signal model of a transistor?

26) What is the specialty of high frequency model of a transistor?

27) What is phase reversal in Common Emitter configuration of transistor?

28) Why is common collector circuit known as emitter follower circuit?

29) Why is RC coupling most widely used coupling between two-stages of a cascaded amplifier?

30) What is push pull amplifier?

31) Define gain and phase margins of an amplifier.

32) What is tuned amplifier?

33) List out advantages of a Field Effect transistor.

34) What is Uni-junction transistor?

35) Classify the transistor based amplifiers.

36) What is feedback amplifier?

37) What is LED/LCD?

38) What is opto-coupler?

39) What are the Barkhausen’s conditions for oscillations?

40) What is Wein bridge oscillator?

41) List out the characteristics of an ideal operational amplifier.

42) Define: CMRR, Slew rate, offset voltage and currents

43) What is virtual ground?

44) What are bi-stable, mono-stable and astable multi-vibrators?

45) How does square waveform differ from pulse waveform?

46) What is Miller sweep circuit?

47) What is meant by time base?

48) What is monolithic IC?

49) What is an instrumentation amplifier?

50) What is the difference between triangular and sawtooth waveforms?

51) What is voltage controlled oscillator?

52) What is phased locked loop?

53) Can you explain any one three pin regulator?

54) What is UPS?

55) What is the working principle of IC 555?

56) How can an RC network circuit be used as integrator?

57) How can an RC network circuit be used as differentiator?

58) What is double differentiator?

**Communication Systems**

59) Why do we need modulation?

60) What is the Band Width used for TV broadcasting?

61) What is the Band Width required for Speech signal transmission?

62) What is ‘auto correlation’ and ‘cross correlation’?

63) What is the figure of merit for modulation with Full Carrier, Double Side Band Suppressed Carrier, and Single Side band modulation?

64) What are the disadvantages of amplitude modulation?

65) What is the Band Width required for Frequency

**Modulation transmission?**

66) Define entropy.

67) State Shannon theorem.

68) Why do you need aliasing filter for PCM before sampler?

69) How is Differential Pulse Code Modulation different from Pulse Code Modulation?

70) Define bit error rate.

71) Mention the bit error rates for Amplitude Shift Keying, Frequency Shift Keying and Phase Shift Keying.

71) What is channel capacity?

72) What is mean by multiple access techniques?

73) Which method of multiple access technique is used for Global System for Mobile communication?

74) Which method of multiple access technique used for Satellite communication?

75) What is the principle of Code Division Multiple Access (CDMA) transmission?

76) How do you analyze the performance of analog communication system?

77) How do you analyze the performance of digital communication system?

78) What is mean by Envelope Distortion in Amplitude Modulation and Demodulation?

79) Why is PLL used?

80) What is mean by half duplex communication?

81) What is mean by simplex communication?

82) What is mean by full duplex communication?

83) How do you decide number of bits required to represent a sample in Pulse Code Modulation?

84) What is quantization noise?

85) How does signal to quantization noise ratio depends on number of bits of a sample?

86) How do you get Frequency Modulation wave from Phase Modulation modulator?

87) How do you get Phase Modulation wave from Frequency Modulation modulator?

88) What is the functionality of matched filter?

89) What is capture effect?

90) What is superheterodyne receiver?

91) What is image frequency in superheterodyne receiver?

92) What are the factors considered for the selection of Intermediate frequency?

93) What is the frequency of Amplitude Modulation broad casting?

94) What is the frequency for Frequency Modulation broad casting?

95) What is the Intermediate Frequency used for Frequency Modulation broad casting?

96) What is the Intermediate Frequency used for Amplitude Modulation broad casting?

97) What is Vestigial Side band? What is its significance?

98) What type of modulation is used for audio in Television broad casting?

98) What type of modulation is used for video in Television broadcasting?

99) Define modulation index.

100) What are pre-emphasis and de-emphasis?

**Digital Electronics**

101) What are basic properties of Boolean algebra?

102) Mention the limitations of Karnaugh map.

103) What is an Essential Prime Implicant?

104) Describe the characteristics of digital ICs.

105) Define Figure of Merit.

106) State advantages and disadvantages of TTL.

107) What is priority Encoder?

108) What is code conversion?

109) Give the applications of Demultiplexer.

110) List out the applications of comparators?

111) What is the difference between Ripple Carry Adder and Carry Look-ahead Adder?

112) Differentiate between Latch and flip-flop

113) What is the operation of T – flip-flop?

114) Define race around condition.

115) What is edge-triggered flip-flop?

116) Define hold time of a flip-flop.

117) What are the two types of shift register counters?

118) What is the use of state diagram?

119) What is mask – programmable ROM?

120) How many words can a 16×8 memory can store?

121) What is the technique adopted by DRAMs?

122) Define hazards. What is static 1 hazard?

123) How can the hazards in combinational circuit be removed?

124) How does an essential hazard occur?

125) What are the types of asynchronous circuits?

126) What are races? Define critical race?

127) Specify the four control signals commonly used by the 8085 MPU.

128) What is the difference between INR & INX instructions?

129) If the clock frequency is 5 MHz, how much time is required to execute an instruction of 18 T-states?

130) Why the lower order address bus is multiplexed with data bus? How they will be de-multiplexed?

131) Differentiate between maskable and non-maskable interrupts.

132) Specify the contents of the registers and the flag status as the following instructions are executed.

MVI A, 01H

MVIB, FFH

MOV C, A

MOV D, B

ADD B

HLT

133) What is Cycle Stealing in direct memory data transfer?

134) Explain the function of READY pin of 8085 MPU?

135) What is the need of a register file in CPU?

136) Distinguish between 8085 and 8086 microprocessor.

137) What is R-2R ladder DAC?

138) Define accuracy of DAC.

139) Define: resolution, conversion time and range of ADC.

**Digital Signal Processing**

140) What is mean by Digital signal processing?

141) What are the advantages of processing a signal digitally compared to its analog form?

142) What are the limitations of digital signal processing?

143) What are the factors that must be considered for processing a signal using digital system?

**Processors**

144) How Digital signal processors are different from other microprocessors?

145) What is the difference between fixed point and floating point Digital signal processors?

146) What is mean by Harvard architecture?

147) What is mean by Very Long Instruction Word architecture?

148) Define zero overhead looping in DSP processor?

149) Define modified Harvard architecture?

150) How many stage pipelining is used in TMS320C54x processor?

151) How does parallel processing is done in Digital signal processor?

**Filters**

152) Classify digital filters?

153) Diffei entiate analog and digital filters?

154) Name the methods used for the design of HR filters?

155) Name the methods used for the design of FIR filters?

156) Where does poles lie for butter-worth filter?

157) Where does poles lie for Chebyshev filters?

158) What is the difference between type-I and type-II chebyshev filters?

159) Mention the properties of Finite Impulse Response filters?

160) Mention the properties of Infinite Impulse Response filters?

**Electro-magnetic Theory**

161) What is an electromagnetic wave?

162) State the applications of electromagnetism.

163) What is Gauss theorem?

164) What is stokes theorem?

165) State and explain Amperer’s law.

166) Explain Poynting vector and power flow in electromagnetic fields.

167) Explain the reflection of plane waves by a perfect dielectric.

168) What are the types of transmission lines?

169) What are the factors that limit the maximum power transfer capability in a transmission line?

170) Explain some of the methods to improve the strength of transmission system.

171) What is a Short Dipole?

172) What is self impedance and mutual impedance?

173) What is Antenna Aperture & What are its types?

174) Which antenna will produce circularly polarized waves?

175) What is the radiation resistance of a half wave dipole?

176) What is meant by antenna beam width?

177) What is meant by front to back ratio?

178) Give the minimum and maximum value of SWR and reflection coefficient.

179) How is the TEio mode launched or initiated in rectangular wave guide using an open ended coaxial cable?

180) Define characteristic impedance and propagation constant of transmission line.

181) What is the physical significance of an infinite line?

182) What are the applications of Smith chart

What is the dominant mode for the TE and TM waves in the rectangular waveguide?

183) Distinguish between wave guide and cavity resonator.

184) What is the value of Zfl for the dissipation-less line?

185) State the condition for distortion-less line.

186) Define skin depth.

187) What is mean by group and phase velocities?

188) What is point source?

189) How does data flow in optical fibre? ‘

190) What is mean by dispersion in optical communication?

191) What is the significance of S parameters?

192) What is mean by processing gain of an antenna?

193) Explain critical angle in optical fibre communication.

194) What is the difference between lumped elements and distributed elements?

**Signals and Systems**

195) What is Fourier statement?

196) Classify signals based on the characteristics.

197) What is mean by non realizable system?

198) When does a system called invertible.

199) Why do you want to covert signal from time domain into frequency domain?

200) How does Fourier series different from Fourier transform?

201) What is the Difference between Discrete Fourier Transform and Discrete Time Fourier Transform?

202) What is the Difference between Laplace Transform and Continuous Time Fourier Transform?

203) What is the Difference between Z-transform and Discrete Time Fourier Transform?

204) What are the properties of twiddle factor?

205) What is Fast Fourier Transform?

206) How do you analyze a Linear Time Invariant system for its stability?

207) What are the methods available for realization of Linear Time Invariant systems?

208) What is mean by canonical structure?

209) State sampling theorem for Low pass signals.

210) State sampling theorem for Band pass signals.

211) What is mean by aliasing?

212) How do you avoid aliasing?

213) How do you reconstruct a signal from its sampled version?

214) How do you describe a Linear Time Invariant system?

215) What is the sampling property of an impulse?

216) What are the properties of convolution?

217) What is Region of Convergence (ROC) in Laplace transform? .

218) What is ROC in Z-transform?

219) Where does location of poles lie in S-plane for the system to be stable?

220) What do you mean by inplace computation for the implementation Fast Fourier Transform algorithm?

221) What is the limitation of Fourier Transform?

222) Define group delay and phase delay.

223) What are the Dirichlet’s conditions for the existence of Fourier transform?

224) State Parseval’s theorem.

225) What are the basic signals?

226) What does unit represents in Unit impulse signal?

227) Define energy and power signals.

228) How do you analyze random signals?

229) What do you mean by auto correlation and cross correlation?

230) What is the condition required for addition of two periodic signal results into a periodic signal?

231) Classify the signals based on their characteristics.

232) How do check the time invariance of a Linear Time Invariant system?

233) How do you test the stability of a Linear Time Invariant system without using location of poles?

I 234) What is the relation between unit step and unit impulse signal?

235) What is mean by Hilbert transform of a signal?

236) List the properties of a Hilbert transform.

237) State initial and final value theorems for Laplace ; transform.

I 238) State initial and final theorems for Z transform.

239) When does a system considered as distortion less?

240) What is the Fourier transform of a Gate function?

241) What is the advantage of transposed form of realization of structure?

242) What is the Difference between Decimation in Frequency – Fast Fourier Transform and Decimation in time Fast Fourier Transform?

243) Write the speed improvement factor of Fast

Fourier Transform compared to Discrete Fourier Transform.

244) How do you find linear convolution using Discrete Fourier Transform?

245) What is the Difference between linear and circular convolution?

246) What is effect in frequency domain of a signal which is shifted in time domain?

247) What is the effect in time domain of a signal which is shifted in frequency domain?

248) What is the relation between number of Fourier coefficients and slope of signal in time domain?

249) How do you find Discrete Fourier Transform of a sequence using linear transformation?

250) Define multirate system.

251) What is mean by interpolation of a sequence?

252) What is mean by decimation of a sequence?

253) How do you change the sampling rate by a non integer factor?

**Network Theory**

254) Ohm’s law is applicable to ———–

255) What is the color code for a 220 05% resistor?

256) When parallel resistors are of three different values, which has the greatest power loss?

257) If the current in a circuit equals 0 A, it is likely that….

258) What is the effect of Resistance on temperature?

259) A Capacitor is driven by a constant current source. The output across the capacitor will

260) Kirchhoff’s current law is valid for which circuits?

261) If current flowing through inductance is constant with respect to time the voltage developed across the inductance ——

262) Two coupled inductances LI and L2 having mutual inductances M are connected in series. Bv a suitable connection, is it possible to achieve a maximum overall inductance?

263) If the voltage across a fixed capacitor is increased, the stored charge will be?

264) The units of measurement of reluctance are?

265) A capacitor has a stored energy of 0.04J with an applied voltage of 200V. The value of capacitance is?

266) Which law is used for finding direction of induced emf?

267) If the voltage across the capacitance is constant with respect to time, the current flowing through it is ?

268) The average power delivered bv passive element is

269) A series RLC circuit consists of R=20 ohms,

X1= j10 ohms & Xc= -j10 ohms is connected across an ac supply of lOOv. The quality factor of the circuit is ?

270) The X & Y in a phasor diagram stands for?

280) The half power bandwidth of a series RLC circuit is?

289) In a resonant circuit, the expression for bandwidth in terms of resonant frequency ‘fo’ & quality factor ‘Q’ is?

290) Q – factor of a resonant circuit is a measure of

291) A connected planar graph has 4 nodes & 5 branches. The number of meshes in the dual graph will be?

292) If n is the number of nodes then the total number of trees are?

293) In the thevenins equivalent circuit, v^ equals

294) Reciprocity theorem is applicable only to www.CampusRecruitment.co.in

295) In a linear circuit, the superposition principle can be applied to calculate the Norton’s theorem is a dual of

296) Compensation theorem is applicable to

297 A network having one are more than one source of emf is known as which network?

298) What are bilateral elements?

299) Two heaters, rated at 1000W, 250V each connected in series across a 250V, 50Hz Ac mains the total power drawn from supply would be?

300) The condition for the validity of ohms’s law is that?

301) The dual of a parallel RC circuit is a ———?

302) A network consists of linear resistors and ideal voltage source. If the value of resistors is doubled, then voltage across each resistor is?

303) Superposition theorem is not applicable for?

304) A current is said to be direct current when its?

305) The form factor of sinusoidal alternating current is?

306) The power factor of an ac circuit lies in between?

307) Unit of reactance power is?

308) If the small capacitance is added to highly inductive circuit then Power factor will be?

309) Real part of admittance is? Imaginary part is?

310) The shunt element of a band pass filter is?

311) The poles and zeros of an all pass network are located in which part of s-plane

312) The Euler’s identity is given by the equation?

313) Unit of inductive reactance is?

314) Substitution theorem is applicable to which networks?

315) Constant k filter is also known as?

316) The units of attenuation are?

317) In a two port network, the Z parameter Z11 can be expressed in terms of ABCD parameters as?

318) In a two port network, the Y parameter Y11 can be expressed in terms of H parameters as?

319) M derived filter is a development of which filter?

320) In the given below circuit, what type of failure will cause the voltage at point B to equal the voltage at point C?

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