STUPIDSID
1 (a)
Explain the properties of S-parameter.
5 M
1 (b)
Explain Stability circles and its importance in amplifier design.
5 M
1 (c)
Explain how noise parameters at microwave frequencies can be determined.
5 M
1 (d)
Explain 1dB compression point.
5 M
2 (a)
Find S parameters of 3 dB attenuator shown in Figure -
10 M
2 (b)
Derive the Transducer Power gain as
10 M
3 (a)
Define the figure of merit in unilateral microwave amplifiers. If unilateral gain of microwave amplifier is
show that
where GT is the transducer gain and GTU is the transducer gain in unilateral case.
show that
where GT is the transducer gain and GTU is the transducer gain in unilateral case.
10 M
3 (b)
A BJT has the following S-parameters as a function of three frequencies. Determine in which of these cases, device is unconditionally stable and which has the greatest stability.
| Frequency (MHz) | S11 | S12 | S21 | S22 |
| 500 | 0.7∠-570 | 0.04∠470 | 10.5∠1360 | 0.79∠-330 |
| 750 | 0.56∠-780 | 0.05∠330 | 8.6∠1220 | 0.66∠-420 |
| 1000 | 0.46∠-970 | 0.06∠220 | 7.1∠1120 | 0.57∠-480 |
10 M
4
Design a transistor oscillator at 4 GHz using FET in a common gate configuration. An inductor of value 5nH is placed in series with the gate to increase stability. Choose a Terminating network to match a 50Ω load and an appropriate tuning network. The S-parameters of the transistor in a common gate configuration are:
S11=2.18∠-35°
S12=1.26∠18°
S21=2.75∠96°
S22=0.52∠155°
S11=2.18∠-35°
S12=1.26∠18°
S21=2.75∠96°
S22=0.52∠155°
20 M
5 (a)
For a two port oscillator at steady state oscillations prove that if, Ï„L Ï„in=1 then Ï„TÏ„OUT=1
10 M
5 (b)
Discuss microwave amplifiers versus microwave oscillators.
10 M
6
GaAs FET has the following scattering and noise parameters at 4 GHz measured with 50Ω systems:
S11=0.6∠-60°
S12=0.05∠26°
S21=1.9∠81°
S22=0.5∠-60°
and Fmin=1.6dB, RN=20Ω and Γopt = 0.62°100°
Assuming the FET to be unilateral, design an amplifier using open circuited shunt stubs and transmission line lengths for a maximum possible gain and a noise figure no more than 2.0dB. Estimate the error introduced in GT due to this assumption.
S11=0.6∠-60°
S12=0.05∠26°
S21=1.9∠81°
S22=0.5∠-60°
and Fmin=1.6dB, RN=20Ω and Γopt = 0.62°100°
Assuming the FET to be unilateral, design an amplifier using open circuited shunt stubs and transmission line lengths for a maximum possible gain and a noise figure no more than 2.0dB. Estimate the error introduced in GT due to this assumption.
20 M
Write shorts notes any two of the following:-
7 (a)
Balanced FET mixer.
10 M
7 (b)
Power Distributed Amplifiers.
10 M
7 (c)
Microwave Resonators.
10 M
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