17923 - Electronics L-B

Learning outcomes

The aim of this course is to provide the basic knowledge for the analysis of simple analog electronic circuits including bipolar transistors and semiconductor diodes.

Required know-how

Basic calculus, complex numbers, Steinmetz, Laplace and Fourier transforms; first order differential equations; basic concepts onelectromagnetic fields; analysis of power dissipation for an electrical circuit and principle of energy conservation; voltage and current Kirchhoff laws applied to both real electrical variables and transformed variables; amplitude and phase Bode diagrams for real poles and zeroes.

Outcome
Frequency-domain analysis of first- and second-order circuits; basic principle of operation of semiconductor diodes and bipolar transistors; analysis of the bias point of circuits including diodes and bipolar transistors; small-signal linear analysis of transistor amplifiers (voltage gain, input and output resistance); basic amplifier stages: common emitter, common source and common base amplifiers; cascaded amplifiers: DC and AC connections; differential amplifiers; current mirror; operational amplifiers: ideal characteristics and main limitations of real devices; simple amplifier and filter stages including operational amplifiers.

Course contents

1. Linear networks



Steinmetz transforms for the sinusoidal analysis of linear networks, Fourier and Laplace transforms, application to the frequency-domain analysis of linear networks (Bode diagrams).

First- and second-order transfer functions; quality factor (Q) and natural frequency (w0). Amplitude diagram of the low-pass II-order filter (dependence on Q).

Power dissipation in electronic circuits.

Definition of voltage, current and power gains.



2. Diodes and Transistors circuits

Basic characteristics of semiconductors: energy bands, doping; conduction in semiconductors (drift-diffusion equations).

Junction diode: basic structure and principle of operation; I-V characteristics; constant-voltage-drop approximation.

Analysis of circuits including diodes; half-wave and full-wave rectifiers.

Bipolar junction transistor (BJT): principle of operation; elementary theory of base transport; regions of operation; simplified analytical model for the static I-V characteristics; “constant Vbe” approximation; Early effect. DC analysis of simple circuits with BJTs.

The PNP BJT.

Introduction to the concepts of bias, linearization and small signal analysis.

Analysis of the four-resistors bias circuit; desensitization with respect to the dispersion of electrical parameters and to the temperature.

Small signal equivalent low-frequency circuits for the diode and for the BJT.

Basic elementary small-signal amplifiers: common emitter, common base, common collector.

Cascaded amplifiers: AC and DC couplings. Analysis of transistor amplifiers by decomposition into elementary stages. BJT differential amplifier.

Diode-connected BJT; basic current mirror.



3. Operational Amplifier (OPAMP)

Introduction to the operational amplifier; main characteristics and ideal model; concept of “virtual short-circuit”.

Inverting amplifier with OPAMP: quiescent point; analysis of the signal voltage gain with ideal OPAMP and assuming a finite differential voltage gain; input differential resistance (for ideal OPAMP).

Analysis of simple amplifiers and filters: non-inverting amplifier; voltage buffer; differential amplifier; instrumentation amplifier; integrator; differentiator; first-order low-pass and high-pass filters.
Main non-ideal effects: finite gain and input-output resistances; voltage offset; bias currents; current and voltage limitations; slew-rate.

Readings/Bibliography

Richard C. Jaeger: Microelettronica 1 Elettronica analogica, McGraw-Hill, 2005.
A. Sedra, K. Smith: Microelectronic circuits, Oxford University press, 1997.
P.U. Calzolari, S. Graffi: Elementi di Elettronica, Zanichelli, 1984.
S. Callegari, Elettronica Analogica di Base, Pitagora Editrice 2000

Teaching methods

Theoretical lessons and exercises concerning the analysis and the design of simple analog circuits.

Assessment methods

Written exam divided into two parts:

1)    questions concerning the theory and the main concepts provided by the course.

2)    analysis of analogue circuits based on BJTs and OPAMP.

Office hours

See the website of Claudio Fiegna