Question Paper: Advanced Microwave Engg : Question Paper Dec 2014 - Electronics & Telecomm. (Semester 8) | Mumbai University (MU)

Advanced Microwave Engg - Dec 2014

Electronics & Telecomm. (Semester 8)

(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
1 (a) What is an unilateral figure of merit of an amplifier?(5 marks) 1 (b) What are the causes of low frequency noise and high frequency noise associated with the mixer?(5 marks) 1 (c) Derive the expression of overall noise figure in three cascaded stages of amplifiers.(5 marks) 1 (d) Prove that scattering matrix is symmetrical and reciprocal.(5 marks) 2 (a) Explain in the detail stability criteria for microwave amplifier.(10 marks) 2 (b) Explain two methods of broadband amplifier design.(10 marks) 3 Design an amplifier to have a gain 10 dB at 6 Ghz using a transistor with the following s-palameters (Z0=50Ω): [ S11=0.61angle-170^{circ}, S21=2.24angle 32^{circ}, S12=0 S22=0.72 angle -83^{circ} ] plot constant gain circle for Gs=1dB and GL=2 dB. Use matching sections with open-circuited shunt stubs.(20 marks) 4

A GaAs FET has the following S parameter and noise parameter at 1GHz (Z0=50Ω) S11=0.7$\angle$$-155^{\circ}$, S12=0, S21=5.0$\angle$180$^{\circ}$, S22=0.51$\angle$-20$^{\circ}$Fmin=3dB, $\Gamma$opt =0.45$\angle$180$^{\circ}$, $R_N=4\Omega$ .Design a Low noise amplifier for a noise figure of 3.5dB and power gain of 16dB.

(20 marks) 5 (a)

A MOSFET is biased for Large signal class A operation with the following small-signal s-parameter at 5GHz.S11=0.55$\angle $-150$^{\circ}$, S12=0.04$\angle $20$^{\circ}$S21=3.5$\angle $170$^{\circ}$, S22=0.45$\angle $30$^{\circ}$The large signal S21=2.8$\angle $180$^{\circ}$.Design a Large signal class A amplifier with max. Transducer gain in 50Ω system.

(10 marks)
5 (b) Derive the necessary condition for two port NR oscillator.(10 marks) 6 (a) Explain in detail signal ended diode mixer. Also explain mixer design aspects.(10 marks) 6 (b)

Design a transistor oscillator at 4GHz using GaAs FET in common gate configuration with 5nH inductor in series. Common gate configuration s-parameters are S11=2.18$\angle $ -35$^{\circ}$, S21=2.75$\angle $96$^{\circ}$,S12=1.26$\angle $18$^{\circ}$, S22=0.52$\angle $155$^{\circ}$.Select $\Gamma_T$ so that Gamma in >1 

(10 marks)

Write short note on:

7 (a) Noise figure test equipment(5 marks) 7 (b) Power amplifier linearity(5 marks) 7 (c) Comparison of microwave amplifier and oscillator.(5 marks) 7 (d) 1dB compression point.(5 marks)

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