Solve the Electronics and Telecommunication Engineering (Conventional) Question Paper of 2011 Engineering Services Examination.
6. (a) (i) What are the three significant difference between Microwave Transistors and Transferred Electron Devices (TED) ? Sketch the two-valley model of band structure of GaAs (Gallium Arsenide).
(ii) On the basis of RWH theory, give the important criteria a semiconductor must satisfy, in order to exhibit negative resistance. 10
(b) (i) Sketch the different Gunn domain modes exhibited by GaAs. Which mode will gave a frequency much higher than the intrinsic frequency of the Gunn diode ?
(ii) A negative resistance parametric amplifier has a signal frequency of 2 GHz, pump frequency of 12 GHz and output resistance of signal generator is 16 ohms. If input resistance of the signal generator is 1 kΩ, calculate the power gain in dB. What will be the power gain, if it is working as a USB converter ? 10
(c) What is the magic in a 'Magic Tee'? With the help of a schematic, show how a magic tee can be used in microwave receiver for constructing a balanced mixer.
If drift length of a Read diod is 20 μm, calculate the drift time of carrier and operating frequency of the diod (carrier drift velocity=105 cm/sec). 10
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