Teaching

Courses

DIGITAL ELECTRONICS (6 credits)
Bachelor Degree in Electrical Engineering - 3rd year
Caltanissetta University annex
2nd semester, academic year 2014/15

Dr. Roberto Macaluso



 Lesson Plan



The aim of the course is to provide students with a basic and broad knowledge in the field of analysis and design of digital electronic systems. The basic elements of a digital system are examined from the electrical point of view, treating the information either as a current or a voltage. During the course, a number of project exercises will be carried out, by using data sheets of commercial integrated circuits (both in bipolar and CMOS technology). These exercises will enable students to master the methodologies for the design of digital electronic systems. Students who attend the course will be able to analyze, identify and resolve issues relating to the design of digital systems and their interface with the user through an analog system. This will enables them to access easily to both the industrial job market and the master degree in Electronics Engineering. The course is closely related to the courses of Electronic Devices, Logic Networks and Analog Electronics.

Introduction to digital electronics
Difference between analog and digital electronics. The monolithic integration. Discrete and integrated circuits. Manufacture of integrated circuits: state of the art of the CMOS technology and future prospects. CMOS image sensors: comparison with CCD. Performance improvement: scaling and its problems. Electronic systems: functional blocks. Levels of functioning system: system, card, integrated and different levels of abstraction. Design issues for different levels of abstraction. Information and power processing.
Digital systems
Basic logic gates. Definitions of logic levels. Noise in logical systems. Noise immunity. Noise margins. Dynamic characteristics of the logic gates. Propagation delay. Fan-in and fan-out.
Switching operations of the bipolar transistor (BJT)
Storage time. Saturating and non-saturating logic. Circuits for non-saturating switching operations. Schottky transistor. Applications of the BJT as a switch: driving a low-power relay, driving a speaker, driving an LED.
Summary on MOSFET
n-MOS, p-MOS. Enhancement and depletion MOSFET. Triode, pinch-off, and cut-off regions. The MOSFET as a switch. Applications: analog switch. Data sheets of commercial integrated devices.
CMOS
Static mode. CMOS as a switch. Pass transistor n and p. Strong and weak levels. CMOS transmission gate.
The digital logic inverter in CMOS technology
Transfer characteristics, logic threshold, noise margins, propagation delay, static and dynamic power dissipation, delay-power product, fan-out and interconnection problems. Description of the properties and the fundamental parameters of a CMOS inverter. Design on the basis of physical parameters. Output stages separators (buffer).
Logic gates in CMOS technology
NAND and OR. Comparison as a function of the physical parameters: problems of area occupation. A method for synthesizing logic functions implemented in CMOS logic: pull-up and pull-down networks. Multiple input CMOS gates. Integrated CMOS logic families: HC, HCT, AC, ACT, AHC, AHCT, ACQ, ACTQ, LV, LVC, ALVC. Data sheets of commercial digital integrated devices.
Main logic families
DL, RTL, DTL, TTL, D-TTL, LS-TTL. Logic gates description. Totem-pole output stage. Main operational characteristics of integrated circuits series advanced logic. Open collector and three-state: properties and applications. Wired AND. Data sheets of commercial digital integrated devices.
BiCMOS family
Properties and advantages over CMOS and TTL families. Logic gates description.
Hint on other logic families
ECL, GaAs technology.
Compatibility and comparison of logic families
Interface circuits.
Combinational circuits
Decoder-encoder, decoder BCD-7 segments, multiplexer/demultiplexer. Examples and applications. LED and LCD displays. Hint on programmable logic devices (PLD). Programmable arrays of AND and OR.
Sequential circuits
SR latch with NAND gates in CMOS, CMOS SR Flip-Flop (FF), CMOS SR FF with pass transistors. JK, T, and D FF. Data sheets of CMOS and TTL commercial digital integrated devices. Application of SR latch: anti-bounce circuit. Multi-position buttons.
Shift registers
S-S, S-P, P-S, P-P. Universal register.
Counter circuits
Asynchronous binary counters: frequency divider. Synchronous Counters. Decade counter in BCD code. Ring counters. Back and forth counters. Data sheets of commercial digital integrated devices.
Multivibrator circuits
Astable multivibrator with CMOS gates. Controlled astable multivibrator. Ring oscillator. Monostable circuits: Monostable with CMOS gates. Integrated monostable. LMC555. Applications of the Schmitt trigger. NAND Schmitt trigger. CMOS 555 timer integrated circuits (monostable and astable).
Analog-to-digital and digital-to-analog conversion
Quantization error. Examples of application of the A/D conversion Structure and properties of a sample and hold circuit. D/A converters with weighted ladder network, with R-2R ladder network. A/D flash conversion, with forward-backward counter, successive approximation, simple ramp, dual slope. Data sheets of commercial digital integrated devices.
Project exercises.

Teaching material:
- Sedra-Smith: Circuiti per la Microelettronica (IV Edizione), Ingegneria2000, 2004
- Paolo Spirito: Elettronica digitale (III Edizione), McGraw-Hill, 2006.
- Teaching notes provided by the lectures.
- Data sheets and application notes of commercial devices of the leading manufacturers.

Assessment:
Oral examination, including a discussion of one of the projects covered during the course.



 Teaching Material



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Communications to the students
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University of Palermo  -  Department of Energy, Information engineering and Mathematical models (DEIM)
viale delle Scienze, Building 9  -  I-90128  Palermo (Italy)