B.TECH - Semester 8 microwave devices and circuits Question Paper 2019 (nov)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- Explain the significance of shift in reference plane in microwave systems.
- What are the features of signal flow graph and its advantages.
- Show that it is impossible to construct a 3 port network i.e lossless, reciprocal and matched at all ports.
- Draw the circuit diagram showing biasing of RF FET structure.
- S-parameters for the HPHFET at 2 GHz with bias voltage $\mathrm{V}_{\mathrm{gs}}=0$ are $\left(\mathrm{Z}_{0}=50 \Omega\right) \mathrm{S}_{11}=0.894<-60.6^{\circ} ; \mathrm{S}_{12}=0.020<62.4^{\circ} ; \mathrm{S}_{21}=3.122<123.6^{\circ}$ and $\mathr...
- Find the frequency of Gunn oscillator of length $12 \mu \mathrm{~m}$. Drift velocity is $2 \times 10^{8} \mathrm{~m} / \mathrm{s}$.
- The drift length in a Gunn is $2.5 \mu \mathrm{~m}$. Determine the min. voltage needed to operate the Gunn.
- Discuss the effect of strip thickness in microstrip lines.
- Write note on circulators.
- At high frequencies why we prefer distributed elements instead of discrete ( $\mathbf{1 0} \boldsymbol{\times} \mathbf{4} \boldsymbol{=} \mathbf{4 0}$ Marks) Answer any two questions from each Module each question carries 10 marks.
- Find the ABCD parameter of a transmission line of length I and propagation factor $\beta$.
- For a load impedance $\mathrm{Z}_{\mathrm{L}}=60-\mathrm{j} 80 \Omega$ design two single stubs (short circuit) shunt tuning networks to match to a $50 \Omega$ line at 2 GHz .
- Design a double stub tuner to match $\mathrm{Z}_{\mathrm{L}}=60-\mathrm{j} 80 \Omega$ to a $50 \Omega$ line at 2 GHz . Stubs are open circuit and are $\lambda / 8$ apart.
- Explain why cavities are required for sustained oscillation of-ve one port devices.
- Design for 18 dB single stage MESFET amplifier operating at 5.7 GHz with S-parameters $\mathrm{S}_{11}=0.5<-60^{\circ} ; \mathrm{S}_{12}=0.02<0^{\circ} \mathrm{S}_{21}=6.5<115^{\circ}$ and $\mathrm{S}_{22}=0.6<-35^{\circ}$ (i) Determine if circuit is...
- Design a NA uwh transistor has gain and a noise figure less than 1.6 dB . Assume Fmin $=1.5 \mathrm{~dB} ; \mathrm{Rn}=4 \Omega \& \Gamma$ opt $=0.5<45^{\circ}$. Also $\mathrm{I}_{\mathrm{C}}=10 \mathrm{~mA} \mathrm{~V}_{\mathrm{CE}}=6 \mathrm{~V}$ ...
- Write note on coupled strip lines.
- Write note on inductors and BPF.
- Explain how to analyze microstrip coupled lines employing even \& odd modes. $$ \text { ( } 6 \times 10=60 \text { Marks) } $$