Question Paper: Advanced Microwave Engg : Question Paper Dec 2013 - Electronics & Telecomm. (Semester 8) | Mumbai University (MU)
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## Advanced Microwave Engg - Dec 2013

### Electronics & Telecomm. (Semester 8)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(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 are the causes of low frequency noise and high frequency noise associated with the mixer?(5 marks) 1 (b) Find S-parameters of two port series network Z=50Ω and ZO=100Ω network.(5 marks) 1 (c) What are the characteristics of power amplifiers?(5 marks) 1 (d) Explain 1dB Compression point.(5 marks) 2 (a) A BJT with IC = 30 mA and VCE = 10V is operated at a frequency of 1 GHz in a 50Ω system. Its S-parameters are -
S11=0.73∠175°
S12=0
S21=4.45∠65°
S22=0.21∠-80°
Determine whether the transistor is unconditionally stable. If yes, calculate optimum terminations, GSmax, GLmax, GTUmax.
(10 marks)
2 (b) Explain using suitable diagrams two methods of designing broad band amplifier.(10 marks) 3 (a) A BJT has the following s-parameters -
S11=0.65∠-95°
S12=0.035∠40°
S21=5∠115°
S22=0.8∠–35°
Is this transistor unconditionally stable? Draw input and output stability circles.
(10 marks)
3 (b) Determine the stability of GaAs FET that has the following S-parameters at 2 GHz in a 50Ω systems both graphically and mathematically -
S11=0.89∠-60°
S12=0.02∠62°
S21=3.1∠123°
S22=0.7∠-27°
(10 marks)
4 (a)

Derive the Transducer Power gain as
$G_T = \dfrac {|S_{21}|^2 (1-|\tau_S|^2) (1-|\tau_L|^2)}{|1-\tau_S\tau_{in}|^2 |1 - S_{22}\tau_L|^2}$

(10 marks) 4 (b) If a one port microwave diode has Γin=1.5∠60° with respect to Z0=50Ω. Design an oscillator for desired frequency of 10GHz.(10 marks) 5 (a) Describe and classify in detail generator tuning networks.(10 marks) 5 (b) Explain in detail single ended diode mixer. What are mixer design considerations?(10 marks) 6 (a) Compare Microwave Amplifiers with Microwave Oscillators.(10 marks) 6 (b) What are the different techniques to obtain power amplifier linearity? Draw and explain feed forward technique.(10 marks) 7 (a) Balanced FET mixer.(5 marks) 7 (b) Noise figure test equipment.(5 marks) 7 (c) Power Distributed Amplifiers.(5 marks) 7 (d) Noise parameters at microwave frequencies.(5 marks)