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TITLES OF THE THEMES FOR THE ADMISSION TEST TO THE
DOCTORATE RESEARCH COURSE IN
“ELECTRICAL AND COMMUNICATION ENGINEERING”
XXII cycle
TEMA N. 1
PART A (60 min)
Answer in short form to the following questions (max 20 lines each answer)
1 The relations between voltages and currents at the ports of a linear, time-invariant two-port
electric device can be given in terms of proper matrices. Show one of these matrices and
describe how to obtain its elements through voltage and current measurements.
2 Given a basis of non orthogonal vectors v1, v2, v3 in a three dimensional space, describe a
method to obtain a basis of orthogonal vectors x1, x2, x3
3 Describe the DTFT (Discrete-Time Fourier Transform) and the DFT (Discrete Fourier
Transform) showing their analogies and differences.
4 Illustrate the main characteristics and differences of voltage feedback and current feedback
amplifiers (VFA and CFA).
5 Describe the high frequency small signal model of a bipolar transistor.
PART B (120 min)
Describe the research and educational activities that you would like to develop during a Ph.D.
program in Electrical and Communication engineering.
Your description must emphasize the methodological point of view, be contained in one A3
sheet and be organized according to the following scheme:
1 Title:
sequence of terms (max 10) defining the subject of the proposed research
2 Abstract:
short summary of the proposed activity (max 100 words)
3 Keywords:
Technical terms that help classifying the subject and technical area for the proposed activity
(min 3 - max 5)
4 State of the art:
Description of the state of the knowledge and of the resources currently available for the
subject of the proposed activity
5 Proposed contribution:
Description of the proposed activity, highlighting theoretical and methodological issues and
stating how and why it would improve the state of the art
6 knowledge:
List the knowledge you should purse during the program, in order to carry out the proposed
activity
7 Activity steps:
Time ordered list of the actions to take in order to carry out the activity (min 3 - max 10
items)
TEMA N. 2
PART A (60 min)
Answer in short form to the following questions (max 20 lines for each answer)
1 Show the concept of wide-sense stationary (WSS) process, and how
it is used to define the models of random signals.
2 Explain what is a matched filter receiver and a correlation receiver in a numeric transmission
system.
3 For a one-input linear time-invariant circuit, consider as output variable the voltage at a
given branch. Show the structure and the meaning of the impulse response.
4 Discuss the closed loop stability of an amplifier using an op amp. Show the compensation
methods using an inverting deriver.
5 Show the block schematics of an analog PLL, and derive the linear equations for the phase
transfer function.
PART B (120 min)
Describe the research and educational activities that you would like to develop during a Ph.D.
program in Electrical and Communication engineering.
Your description must emphasize the application point of view, be contained in one A3 sheet
and be organized according to the following scheme:
1 Title:
sequence of terms (max 10) defining the subject of the proposed research
2 Abstract:
short summary of the proposed activity (max 100 words)
3 Keywords:
Technical terms that help to classify the subject and technical area of the proposed activity
(min 3 - max 5)
4 State of the art:
Description of the state of the knowledge and of the resources currently available for the
subject of the proposed activity
5 Proposed contribution:
Description of the proposed activity, highlighting application aspects and stating how and why
it would improve the state of the art
6 knowledge:
List the knowledge you should purse during the program, in order to carry out the proposed
activity
7 Activity steps:
Time ordered list of the actions to take in order to carry out the activity (3 to 10 items)
TEMA N. 3
PART A (60 min)
Answer in short form to the following questions (max 20 lines for every answer)
1 From the sampling theorem to the ADC. Show the aliasing phenomenon and the use of an
antialiasing filter before an ADC converter.
2 Consider a linear, n-th order ordinary differential equation with constant coefficients (n>1).
Show a method to rewrite the equation as an equivalent system of n first-order differential
equations. Can the method be extended to the non-linear case?
3 Given N values f(xi) of a function f(x) for a set of points xi (i=1,…N) in an interval [a,b],
show some interpolation methods to estimate f(x) for any x in [a,b]
4 Define numeric modulation based on I and Q signals (in phase and quadrature), and show
how these signals are received
5 Describe the buck converter, derive the voltage ratio M=Vo/Vi for continuous and
discontinuous conduction mode, assuming ideal devices.
PART B (120 min)
Describe the research and educational activities that you would like to develop during a Ph.D.
program in Electrical and Communication engineering.
Your description must emphasize the educational point of view, be contained in one A3 sheet
and be organized according to the following scheme:
1 Title:
sequence of terms (max 10) defining the subject of the proposed research
2 Abstract:
short summary of the proposed activity (max 100 words)
3 Keywords:
Technical terms that help the classification of the subject and technical area of the proposed
activity (min 3 - max 5)
4 State of the art:
Description of the state of the knowledge and of the resources already available for the
subject of the proposed activity
5 Proposed contribution:
Description of the proposed activity, highlighting also educational issues, and stating how and
why it would improve the state of the art
6 knowledge:
List the knowledge you should purse during the program, in order to carry out the proposed
activity
7 Activity steps:
Time ordered list of the actions to take in order to carry out the activity (min 3 - max 10
items)