STUPIDSID
1 (a)
A lossless co-axial cable has wavelength of electric and magnetic field of l=20cm of 960MHz. Find the relative dielectric of insulation.
5 M
1 (b)
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 (c)
For a parallel copper plate transmission line operated at 1GHz, the following parameters are given:
W=6mm, d=1mm, σdielectric=0.125mS/m, εr=2.25.
. Find the line parameters R, L, G and C per unit length.
W=6mm, d=1mm, σdielectric=0.125mS/m, εr=2.25.
. Find the line parameters R, L, G and C per unit length.
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1 (d)
A lossless 50 Ω 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 50Ω .
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2 (a)
A transmission line of characteristic impedance of Z0=50A transmission line of characteristic impedance of Z0=50Ω and length d=0.15? is terminated into load impedance of ZL =(25-j30)Ω.
Find τ0,Zin(d) and SWR.
Find τ0,Zin(d) and SWR.
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2 (b)
A lossless transmission line with Z0=50Ω is 10cms long f=800MHz, vp=0.77c. If the input impedance is Zin=j60Ω, find CL. What length of a short circuited transmission line would be needed to replace ZL.
10 M
3 (a)
To suppress noise in a digital communication system a bandpass RF filter is required with a passband from 1.9GHz to 2GHz. The minimum attenuation of filter at 2.1GHz and 1.8GHz should be 30dB. Assuming that a 0.5dB ripple in passband can be tolerated, design a filter that would be using minimum number of components
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3 (b)
Derive expression for internal, external and loaded quality factors for standard series and parallel resonant circuit.
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4 (a)
The intrinsic carrier concentration is typically recorded at room temperature.
For GaAs we find at T=300oK the effective densities of state
Nc=4.7x1017 cm-3,
Nv=7.0x1018 cm-3. .
Assuming that the bandgap energy of 1.42eV remains constant,
(a) Find the intrinsic carrier concentration at room temperature.
(b)Compute ni at T=400°K.
For GaAs we find at T=300oK the effective densities of state
Nc=4.7x1017 cm-3,
Nv=7.0x1018 cm-3. .
Assuming that the bandgap energy of 1.42eV remains constant,
(a) Find the intrinsic carrier concentration at room temperature.
(b)Compute ni at T=400°K.
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4 (b)
Explain in brief the principle of operation of HEMT and RF FET along with their construction.
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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.
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5 (b)
Explain Ebers-Moll model of a large signal BJT. Also give details of transport representation.
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6 (a)
Explain in brief the determination of AC parameters of bipolar transistors.
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6 (b)
Show that in the fig d12.1, the feedback capacitance Ccb can be expressed as
CM1=Ccb(1-vce/vbe) and CM2=Ccb(1-vbe/vce), on the input and output port
Assume that the input and output voltages are approximately constant, and keep in mind that vce is negative under CE configuration.
CM1=Ccb(1-vce/vbe) and CM2=Ccb(1-vbe/vce), on the input and output port
Assume that the input and output voltages are approximately constant, and keep in mind that vce is negative under CE configuration.
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Write short notes on:
7 (a)
DC characterization of BJT.
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7 (b)
Realization of RF filters using Kuroda s identities.
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7 (c)
Terminations used in microstrip line.
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7 (d)
Equivalent circuits of resistors, inductors and capacitors.
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