B.TECH - Semester 8 microwave devices and circuits Question Paper 2008 (may)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- Draw the even and odd mode field distributions in a microstrip coupled line.
- Why we go for S-parameters at high frequencies?
- How circuit analysis can be extended to microwave networks and list the merits and demerits.
- What does theory of small reflection imply.
- Draw the circuit showing RF bias of a transistor.
- What is the avalanche zone velocity of a trappat diode if current density $=25 \mathrm{kA} / \mathrm{Cm}^{2}$ and doping concentration $=1.8 \times 10^{15} / \mathrm{cm}^{3}$.
- Explain the working of TRAPPAT.
- Explain the significance of Richard's transformation.
- Write note on resonators.
- List the characteristics of coupled lines. ( $\mathbf{1 0} \boldsymbol{\times} \mathbf{4 = 4 0}$ Marks) P.T.O. Answer any two Questions from each Module. Each Question carries 10 marks.
- Using Smith chart design all possible configurations of lumped 2 element matching network that match $Z_{s}=(50+j 25) \Omega$ to $Z_{L}=(25-j 50) \Omega$. Assume $Z_{0}=50 \Omega$ and working frequency 2 GHz .
- Using open single series stub design a matching network that will transform $Z_{L}=(100+j 80) \Omega$ to a $50 \Omega$ feed line (smith Chart)
- Design a quarter wave transformer to match $10 \Omega$ load to a $50 \Omega$ line at $f_{0}=3 \mathrm{GHz}$. Determine the percent bandwidth for which SWR $\leq 1.5$
- Explain the mechanism of oscillation of IMPATT diode and its operating principle. List the features and application of IMPATT.
- Given amplifier $r_{s}=0.5<120^{\circ} ; r_{L}=0.4<90^{\circ}$ $S_{11}=0.6<-160^{0} ; S_{12}=0.045<16^{0} ; S_{21}=2.5<30^{0}$ and $S_{22}=0.5<-90^{0}$. N - 6644 (a) Determine $\mathrm{G}_{\mathrm{T}}, \mathrm{G}_{\mathrm{A}}$ and $\mathrm{G}_{\mat...
- Given amplifier $r_{s}=0.5<120^{\circ} ; r_{L}=0.4<90^{\circ}$ $S_{11}=0.6<-160^{0} ; S_{12}=0.045<16^{0} ; S_{21}=2.5<30^{0}$ and $S_{22}=0.5<-90^{0}$. N - 6644 (b) Power levels $\mathrm{P}_{\mathrm{L}}, \mathrm{P}_{\text {IN }}, \mathrm{P}_{\text...
- Given amplifier $r_{s}=0.5<120^{\circ} ; r_{L}=0.4<90^{\circ}$ $S_{11}=0.6<-160^{0} ; S_{12}=0.045<16^{0} ; S_{21}=2.5<30^{0}$ and $S_{22}=0.5<-90^{0}$. N - 6644 (c) Mismatch loss at input and output of transistor
- Given amplifier $r_{s}=0.5<120^{\circ} ; r_{L}=0.4<90^{\circ}$ $S_{11}=0.6<-160^{0} ; S_{12}=0.045<16^{0} ; S_{21}=2.5<30^{0}$ and $S_{22}=0.5<-90^{0}$. N - 6644 (d) input and output reflection coefficient
- Given amplifier $r_{s}=0.5<120^{\circ} ; r_{L}=0.4<90^{\circ}$ $S_{11}=0.6<-160^{0} ; S_{12}=0.045<16^{0} ; S_{21}=2.5<30^{0}$ and $S_{22}=0.5<-90^{0}$. N - 6644 (e) VSWR $_{\text {IN }}$ \& VSWR $_{\text {OUT }}$
- Using lumped element network design broad band amplifier in the range 300 700 MHz with a transducer power gain of 10 dB . (Use Smith chart) | Freq. | $S_{11}$ | $S_{12}$ | $S_{21}$ | $S_{22}$ | | :--- | :--- | :--- | :--- | :--- | | 300 | $0.3<-45^{...
- Design a low pas filter for fabrication using microstrip lines. Specifications are cut off freq. $4 \mathrm{GHz}, 3^{\text {rd }}$ order, impedance $50 \Omega$ and a 3 dB equal ripple characteristic.
- Write notes on terminations; attenuators and capacitors.
- Write notes on switches and limiters. $$ (6 \times 10=60 \text { Marks }) $$