ELECTRONICS FOR DIGITAL SYSTEM
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- Versione italiana
- Academic year
- 2022/2023
- Teacher
- PIERO OLIVO
- Credits
- 6
- Curriculum
- Ingegneria elettronica e wireless
- Didactic period
- Secondo Semestre
- SSD
- ING-INF/01
Training objectives
- The course takes up the main topics seen in the course of Digital Electronic Systems, from a logical / system point of view, and examines in detail the circuit realizations, thus allowing to understand the motivations underlying the different design choices.
The main knowledge acquired will concern the analysis and design techniques of integrated digital circuits and systems with attention to problems related to power consumption, signal integrity, and their testing. In particular:
• basic elements of semiconductor technology;
• fundamental characteristics of a CMOS circuit;
• basic knowledge to face the study of complex digital systems and their interconnections with the constraints imposed by the required performance in terms of cost, speed, area occupation, noise immunity and power consumption;
• operation and sizing of the static and dynamic combinatorial blocks;
• operation and sizing of sequential, static and dynamic circuits;
• timing of electronic circuits: distribution of the synchronism signal and deviations from expectations;
• testing of digital integrated circuits.
The main skills (that are the ability to apply knowledge acquired) will be the analysis and design of digital systems using dedicated components. In particular:
• analyze the behavior of digital circuits in static and dynamic conditions;
• identify the design constraints that determine the size of a digital circuit;
• identify the most appropriate combinational and sequential circuits for the design of a specific electronic system;
• understand the timing problems that may arise during the design of an electronic system;
• identify the most suitable test procedure for an electronic system;
• identify the design constraints of a self-test system in a digital integrated circuit. Prerequisites
- To follow the course a full knowledge of the basics of Digital Electronic Systems is mandatory.
In particular it is necessary to have acquired and assimilated the following knowledge provided by courses of the 1st and 2nd year:
• basic concepts of mathematics and differential computation;
• knowledge of the basic concepts of the physics, especially those related to electromagnetic;
• knowledge of the circuit theory: Ohm and Kirchhoff lows and their practical application; methods to analyze electrical circuits in steady and transient states:
• knowledge of the logic networks: binary arithmetic; combinational and sequential circuits;
• ability in analyzing small digital systems at the logic level. Course programme
- The course includes 60 hours. By treating basic topics there are no lab applications.
Introduction to the course
Summary of key points seen in the course of Digital Electronic Systems
Semiconductor technology
Semiconductors - Diode - Basic technological processes: oxidation, photolithography, doping - Considerations on silicon technology costs
MOS transistor
MOS transistor physics - Threshold voltage - Ids / Vds characteristic - Examples of nMOS polarization pMOS transistor
Static logic gates
Logical families (comparison parameters) - Static and dynamic characteristics - CMOS inverter - Static characteristic - Logic threshold - Symmetrical and minimum area sizing - Dynamic power consumption - Short circuit and leakage power consumption - Connection modeling - Resistors - Capacity - Switching transients of a CMOS inverter - Switch model - Transients in a NOR CMOS - Comparison NAND-NOR - FCMOS - Capacity trend - Switching activity - Signal statistics - Correlations between signals – Differential logic (DCVSL) - Logics with pass-transistor - Problems in pass-transistor logics. Use of level restorer – Pass-transistors with reduced threshold - Transfer gate
Dynamic logic gates
Capacitive cross talk - Capacitive divider - Dynamic logic: speed, power consumption, switching activity - Leakage current - Charge redistribution - Capacitive coupling - Connection between dynamic circuits - Domino - Summary of the different combinational circuits
Ground bouncing and EMC issues
RC lines and transmission lines
Resistance trend - Distributed RC networks - Examples of distributed RC networks - Transmission lines - Characteristic impedance - Reflected wave and transmitted wave - Detailed examples of behavior as a function of source resistance - Real case with CMOS circuits - Load and source matching - Interval of the ratio Rs / Zo
Sequential circuits
Sequential circuits – Timings - Edge triggered registers - Level sensitive latches - Flip-flops - Clock overlapping - Dynamic registers - Flip flop SR - C2MOS - Timing and synchronism - Synchronous and timed asynchronous systems - Skew - Effects on performance and functionality - Jitter - Effect on performance - Combined effect of skew and jitter - Origin of skew and jitter - Parallelism and pipeline - Techniques of clock distribution - Latch-based synchronization - Self-timed logic - "End of operation" circuits - Replication of delay - Control signals
Consumption-speed relations
Power control - Double power supply and double threshold voltage - Run-time control of the power supply
Integrated circuit testing
Cost of testing - Definitions - Characterization & production testing - Parametric and functional testing - Test philosophy - Automated generation of test vectors - Fault simulation - Example of controllability and observability of a fault - Random generation - Design For Testability (DFT) - Economic aspects of DFT – “Ad hoc” methods - Scan design - Registers for scan design - Partial Scan - BIST: philosophy, advantages and disadvantages - BIST architecture - Random and pseudorandom generation - ALFRS - Weighted generation - Circuit response analysis - Signature analysis - Estimation of the aliasing error - MISR - Design procedure for the BIST - Boundary Scan test: commands and functions Didactic methods
- On an experimental basis the course will be held in "inverted classroom" mode. This means that the lessons have already been videotaped and can be used independently by the students, following a time schedule proposed by the teacher. Every week there will be a classroom meeting in which the main points of the lessons proposed for the previous week will be repeated by the teacher, questions will be asked that will be used by the student for a self-assessment and some exercises will be solved. These weekly classroom meeting will also be available remotely.
Learning assessment procedures
- The aim of the exam is to verify at which level the learning objectives previously described have been acquired.
The examination is divided in 2 sections that will take place in the same day.
• One test (multiple choice questions or solutions of numeric exercises) based on all the topics tackled in the class, with the aim of evaluating how deeply the student has studied the subject and how he is able to understand the basic topics analyzed. This section is selective (the student that does not show a sufficient knowledge of the subject, cannot be admitted to the following sections.) To pass this test it is required to get at least 8 points out of 20. The time allowed for this test is 50'. It is not allowed consulting any textbook or using any PC, smart phone, calculator….;
• One oral section, where the ability of linking different subjects related to the digital electronics is evaluated, rather than the ability of “repeating” specific topics tackled in the course. To pass this test it is required to get at least 5 points out of 13. Passing the test is a witness of having acquired the knowledge of the methods for the analysis of complex digital systems and their interconnections in the presence of constraints on cost, speed, area occupancy and noise immunity.
Given the complexity of many circuit diagrams, the student is not required to know how to redesign them. The student can use the schemes seen in class and on which he/she has studied. The goal of the study, in fact, is not to memorize circuit diagrams that, probably, in a few years will no longer be used, but you understand the theoretical, practical and economic reasons that led to the definition of the specific circuit solutions .
The preparation of the student will be evaluated, therefore, on the ability to remember diagrams or formulas, but on the ability to explain the reasons that led to specific and circuits and to identify possible limitations.
The final mark is the sum of the 2 marks.
To pass the exam it is necessary to get at least 18 point out of 33.
If one of the 2 tests is not passed or if the final mark is below 18, it is necessary to repeat all the exam’s sections.
Passing the exam is proof of having acquired the ability to apply knowledge relating to technologies for digital signal processing and to analyze the behavior of circuits and digital electronic systems in the different areas of information and communication technology. Reference texts
- Teacher’s handouts. The teaching material will be fully available before the course starts
