1 (a)
Explain Large Signal characterization with reference to load pull contours. How is it measured?

5 M

1 (b)
What are the causes of low frequency noise and high frequency noise associated with the mixer?

5 M

1 (c)
Define and explain with neat diagram noise correlation matrix for general noisy two port network.

5 M

1 (d)
What is unilateral figure of merit of an amplifier?

5 M

2 (a)
If the transistor has following S-parameters at 5Ghz with 50Ω impedance.

S

S

S

S

Determine the stability criteria and plot the stability circles.

S

_{11}=0.6∠–175°S

_{12}=0.02∠20°S

_{21}=2.2∠35°S

_{22}=0.6∠-95°Determine the stability criteria and plot the stability circles.

10 M

2 (b)
Derive the parameters of an Amplifier:

(i) Power gain (G)

(ii) Available gain (GA)

(iii) Transducer gain (GT)

(i) Power gain (G)

(ii) Available gain (GA)

(iii) Transducer gain (GT)

10 M

3 (a)
Explain using suitable diagrams two methods of designing broadband amplifier.

10 M

3 (b)
A BJT with I

S

S

S

S

Determine whether the transistor is unconditionally stable. If yes, calculate optimum terminations, G

_{C}= 30 mA and V_{CE}= 10V is operated at a frequency of 1 GHz in a 50Ω system. Its S-parameters are -S

_{11}=0.73∠175°S

_{12}=0S

_{21}=4.45∠65°S

_{22}=0.21∠-80°Determine whether the transistor is unconditionally stable. If yes, calculate optimum terminations, G

_{Smax}, G_{Lmax}, G_{TUmax}.
10 M

4 (a)
A certain GaAs MESFET has following noise figure parameters measured at V

F

Plot noise figure circles for given values of f

_{ds}= 50, I_{ds}= 20 mA with 50Ω resistor once for frequency of 9 GHz,F

_{min}= 4dB, Γ_{opt}=0.55∠175, R_{0}= 4Ω.Plot noise figure circles for given values of f

_{1}at 2, 2.5, 3.5, and 4.5 dB.
15 M

4 (b)
Define stability. List the various criteria for stability.

5 M

5 (a)
If a one port microwave diode has Γ

_{in}=1.5∠60° with respect to Z_{0}=50Ω. Design an oscillator for desired frequency of 10GHz.
12 M

5 (b)
For a two port oscillator at steady state oscillations prove that if τ

_{L}τ_{in}=1 then τ_{in}τ_{out}=1
8 M

6
A certain MESFET is biased for large signal class A operation with following small signal S-parameters at 5GHz:

S

S

S

S

The large signal forward transmission coefficient S

S

_{11}=0.55∠-150°S

_{12}=0.04∠20°S

_{21}=3.5∠170°S

_{22}=0.45∠-30°The large signal forward transmission coefficient S

_{21}is measured to be S_{21}=2.1∠180°. Design a large-signal class A amplifier with maximum transducer gain in a 50Ω system. Assume (±)0.5dB error in gain. What is the high-power amplifier gain?
20 M

7 (a)
Write a note on optimal loading used in 1+PA design.

10 M

7 (b)
A wideband amplifier (2-4 GHz) has gain of 10dB, an O/P power gain of 10dBm and a noise figure of 4dB at room temperature. Find the output noise power in dBm.

10 M

More question papers from Advanced Microwave Engg