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Code: 15A04804

B.Tech IV Year II Semester (R15) Advanced Supplementary Examinations July 2019
RF INTEGRATED CIRCUITS
(Electronics & Communication Engineering)

Time: 3 hours Max. Marks: 70

PART ? A
(Compulsory Question)

*****
1 Answer the following: (10 X 02 = 20 Marks)
(a) Calculate the resonant frequency of a parallel RLC tank, given L = 1 nH, C = 1 pF.
(b) State skin effect.
(c) Write the wave equation in one space dimension.
(d) In an open-circuit time constant if R
1
= R
2
= 10 k ? and C
1
= C
2
= 100 pF, what are the pole
frequencies?
(e) Having the noise factor, F = SNR
i
/ SNR
o
give the expression to find noise figure.
(f) Differentiate between power match and noise match.
(g) In a VCO if CM change at X and Y is indistinguishable from a change in V
cont
, then what will be the
change in the oscillation frequency?
(h) While constructing a charge-pump PLL using PFD/CP, the loop ideally forces the input phase error
(i) Define fractional frequency.

PART ? B
(Answer all five units, 5 X 10 = 50 Marks)

UNIT ? I

2 Draw the phasor diagram for a parallel RLC circuit. And derive the expression for impedance and
current triangle of the circuit.
OR
3 (a) Differentiate between Pi match and T match.
(b) Why does the skin effect occur? Mention the factors affecting skin effect in a conductor carrying
a.c current.

UNIT ? II

4 An air-filled 50 ? coaxial line has a loaded VSWR of 3.3 at a frequency of 3 GHz. Replacing the load
with a short cause the voltage minimum to move 1.0 cm towards the generator. What is the
OR

Contd. in page 2

Page 1 of 2
R15
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Code: 15A04804

B.Tech IV Year II Semester (R15) Advanced Supplementary Examinations July 2019
RF INTEGRATED CIRCUITS
(Electronics & Communication Engineering)

Time: 3 hours Max. Marks: 70

PART ? A
(Compulsory Question)

*****
1 Answer the following: (10 X 02 = 20 Marks)
(a) Calculate the resonant frequency of a parallel RLC tank, given L = 1 nH, C = 1 pF.
(b) State skin effect.
(c) Write the wave equation in one space dimension.
(d) In an open-circuit time constant if R
1
= R
2
= 10 k ? and C
1
= C
2
= 100 pF, what are the pole
frequencies?
(e) Having the noise factor, F = SNR
i
/ SNR
o
give the expression to find noise figure.
(f) Differentiate between power match and noise match.
(g) In a VCO if CM change at X and Y is indistinguishable from a change in V
cont
, then what will be the
change in the oscillation frequency?
(h) While constructing a charge-pump PLL using PFD/CP, the loop ideally forces the input phase error
(i) Define fractional frequency.

PART ? B
(Answer all five units, 5 X 10 = 50 Marks)

UNIT ? I

2 Draw the phasor diagram for a parallel RLC circuit. And derive the expression for impedance and
current triangle of the circuit.
OR
3 (a) Differentiate between Pi match and T match.
(b) Why does the skin effect occur? Mention the factors affecting skin effect in a conductor carrying
a.c current.

UNIT ? II

4 An air-filled 50 ? coaxial line has a loaded VSWR of 3.3 at a frequency of 3 GHz. Replacing the load
with a short cause the voltage minimum to move 1.0 cm towards the generator. What is the
OR

Contd. in page 2

Page 1 of 2
R15

Code: 15A04804

5 In the folded cascade circuit shown in figure below, all transistors have the same ?C
ox
(W/L), the
same ? and I
D2
= 2I
D1
. Find the gain and the output resistance of the amplifier (in terms of g
m1
and r
01

only).

UNIT ? III

6 Lay out an LNA and connect its input to a pad through a metal line with the length of 200 ?m and
width of 0.5 ?m. By assuming a noise figure of 2dB for the LNA and a sheet resistance of about
40 m ? for the metal line determine the overall noise figure. Neglect the input-referred noise current
of the LNA.
OR
7 Which device is used to convert baseband signal or IF frequency to a higher IF or RF frequency for
efficient transmission in transmitters? Explain its operation in detail.

UNIT ? IV

8 Which amplifier operates linearly across the full input and output range while the transistors remain
ON? Explain in detail with necessary equations.
OR
9 (a) Write a brief note on resonators.
(b) If the input frequency changes by ? ?, how much is the change in the phase error? Assume the loop
remains lock.

UNIT ? V

10 (a) During synthesizer settling, the power amplifier in a transmitter is turned OFF. Explain why?
(b) Compute the required reference frequency and range of divide ratios for an integer-N synthesizer
designed for a Bluetooth receiver for direct conversion and sliding-IF down conversion with
f
LO
=(2/3) f
RF
.
OR