STUPIDSID
1 (a)
A typical PCB substrate consists of Al2O3 with a relative dielectric constant of 10 and a loss tangent of 0.0004 at 10 GHz. Find the conductivity of the substrate.
5 M
1 (b)
Draw the lumped element circuit model for a transmission line. Derive the expression for voltage and current travelling waves.
5 M
1 (c)
Explain current flow in p-n junction and give the expression for Idiff in terms of diffusion constant and Vdiff in terms of doping concentration.
5 M
1 (d)
A lossless 50Ω microstrip line is terminated into a load with admittance of 0.05mS. What additional impedance has to be placed in parallel with load to assure impedance of 50 Ω.
5 M
2 (a)
A short circuited 50Ω transmission line section operated at 1GHz and possesses a phase velocity of 75% of the speed of light. Use both the analytical and the Smith chart approach to determine the shortest length required to obtain:
(i) 5.6 pF capacitor
(ii) 4.7 nH inductor.
(i) 5.6 pF capacitor
(ii) 4.7 nH inductor.
10 M
2 (b)
Explain various terminations used in Microstrip transmission lines.
10 M
3 (a)
Starting with the equation for normalized admittance-
y=g+jb= 1-τ/1+τ
Prove that the circle equations for the Y-smith chart are given by the following two formulas:
For the constant conductance circle as \[{\left(τ_r+\frac{g}{g+1}\right)}^2={τ_i}^2{\left(\frac{1}{g+1}\right)}^2 \]
(ii)For the constant susceptance circle as \[{\left(τ_r+1\right)}^2+{\left(τ_i+\frac{1}{b}\right)}^2={\left(\frac{1}{b}\right)}^2\]
y=g+jb= 1-τ/1+τ
Prove that the circle equations for the Y-smith chart are given by the following two formulas:
For the constant conductance circle as \[{\left(τ_r+\frac{g}{g+1}\right)}^2={τ_i}^2{\left(\frac{1}{g+1}\right)}^2 \]
(ii)For the constant susceptance circle as \[{\left(τ_r+1\right)}^2+{\left(τ_i+\frac{1}{b}\right)}^2={\left(\frac{1}{b}\right)}^2\]
10 M
3 (b)
Explain with equivalent circuits the RF behavior of resistor,inductor and capacitor.
10 M
4 (a)
State and prove Kuroda's four Identities.
10 M
4 (b)
Explain in brief the principle of operation of HEMT and RF FET along with their construction.
10 M
5 (a)
Design a prototype low pass Butterworth filter that will provide at least 20dB attenuation at f=2f3dB. Compute and plot the amplitude response for 0 to 5GHz.
10 M
5 (b)
What is Miller Effect? Show that:
\[C_{M1}=C_{cb}\left(1-\frac{V_{ce}}{V_{be}}\right)\ \\ \text{on the input port and } C_{M2}=C_{cb}\left(1-\frac{V_{be}}{V_{ce}}\right)\]on the output port.
\[C_{M1}=C_{cb}\left(1-\frac{V_{ce}}{V_{be}}\right)\ \\ \text{on the input port and } C_{M2}=C_{cb}\left(1-\frac{V_{be}}{V_{ce}}\right)\]on the output port.
10 M
6 (a)
Derive expression for internal, external and loaded quality factors for standard series and parallel resonant circuit.
10 M
6 (b)
Explain functionality of BJT.
10 M
Write short notes on:
7 (a)
Butterworth filter.
5 M
7 (b)
Chip components.
5 M
7 (c)
Schottky contacts.
5 M
7 (d)
Richard's transformations.
5 M
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