Analog Electronic

Subject description

The course provides knowledge of the basics of analog electronic circuits based on operational amplifiers (OA). Students are introduced to fundamental concepts in linear electronics (phasors, the response of linear circuits to sinusoidal excitation, transient and steady-state responses, and transfer functions), the distinction between linear and nonlinear circuits, and the basics of circuit analysis (systematic equation writing, nodal analysis, and modified nodal analysis).

Next, the fundamental properties of OA are explored. Students are familiarized with the response to slow signals, linear properties (gain, common-mode rejection ratio, and input and output impedance), and nonlinear properties (saturation). Since OAs are not used in linear circuits without feedback, a brief overview of negative feedback is given, examining its impact on gain and nonlinearity. The principle of virtual short-circuit, which constitutes the basis for the analysis of linear circuits wits OAs, is explained.

This is followed by a detailed analysis of two fundamental OA circuits, the non-inverting and the inverting amplifier. Circuits such as summing amplifier, voltage follower, transimpedance and transadmittance converters, and current amplifiers are derived.
Imperfections that occur at the input of OA (input offset voltage, input bias currents, and input offset current) are explained and the methods for their compensation are explored. The section concludes with an explanation of temperature drift, aging, and the low-frequency model of Op-Amps.

Basic concepts of frequency domain analysis are presented (poles and zeros of the transfer function, Bode plot, transient response, and stability of linear circuits). The impact of negative feedback on the frequency response and the frequency bounds of an amplifier is explained. The acquired knowledge is then used for describing the frequency response of an OA. Stability analysis of feedback amplifiers using Bode plots is covered, followed by the notions of frequency compensation, PSRR, and slew rate.

With the acquired knowledge some common linear circuits based on OAs are explained (differential and instrumentation amplifiers, amplifiers utilizing small resistors for achieving high gain, grounded-load transadmittance converters, integrators, differentiators, active filters with one and two poles, and s-C filters).

The last section focuses on the use of OAs in nonlinear circuits. Topics covered include half-wave and full-wave rectifiers, average, peak, peak-to-peak, and RMS value detectors, amplifiers with nonlinear transfer functions (quadratic, exponential, and logarithmic), multipliers and dividers, clippers, comparators, Schmitt triggers, relaxation oscillators, and monostable multivibrators.

The subject is taught in programs

Objectives and competences

The objective of the course is to provide students with fundamental knowledge of linear and nonlinear electronic circuits based on operational amplifiers. Students will gain knowledge of operational amplifier's characteristics, its imperfections, and stability. In addition, they will learn the fundamentals of negative feedback systems, circuit analysis in the frequency domain, Bode plots, and the notions of transfer function poles and zeros. Students will also gain an understanding of basic linear and nonlinear circuits with operational amplifiers and learn how to analyze them.

Teaching and learning methods

The lectures provide theoretical background and solutions of simple examples. Complete study material is available to students. As part of laboratory practice students analyze more advanced circuits and extend their knowledge with measurements and simulations of various operational amplifier-based circuits.

Expected study results

After successful completion of the course students should be able to:

systematically write down circuit equations,
select an operational amplifier based on required specifications,
draw and interpret a Bode plot,
utilize negative feedback,
recognize, analyze, and apply basic operational amplifier circuits,
synthesize simple circuits with operational amplifiers,
measure basic properties of circuits with operational amplifiers.

Basic sources and literature

Bűrmen, Á., Linearna elektronika, Založba FE, 2012.
Basarič, N., Analogna vezja z operacijskim ojačevalnikom, Založba FE, 2002.
Horowitz, P., Hill. W., The art of electronics, Cambridge University Press, New York, 2015.
Horowitz, P., Hill. W., The art of electronics : the x-chapters, University Press, New York, 2021.
Tuma, T., Bűrmen, Á., Circuit Simulation with SPICE OPUS, Theory and Practice. Springer, 2009.