Linear Electronics

The course provides knowledge of fundamentals of linear electronic circuits at the transistor level. It begins with a review of basic concepts (definition of linear electronics, components, operating point, deviation from the operating point, phasors, Thévenin and Norton equivalent circuits, power, load matching, and transfer function). 

Next, fundamentals of two-port networks are introduced. Students learn about admittance, impedance, and hybrid parameters, as well as parameter conversion. Basic properties of two-port networks are discussed, including voltage and current gain, input and output admittance, power gain, reciprocity, activity, passivity, absolute stability, and potential instability. Orientations of 3-terminal circuits are discussed and the procedure for parameter conversion resulting from a change in orientation is explained. 

Linearized models of basic nonlinear electronic components (diode, Zener diode, bipolar transistor, MOSFET, and junction FET) are introduced. Students learn how to calculate the circuit's operating point based on simplified nonlinear characteristics of transistors. The concept of deviation from the operating point is introduced and large signal analysis is explained, leading to the calculation of nonlinear distortions. Assuming small deviations from the operating point the small-signal circuit model is introduced. 

Orientations of the bipolar transistor and unipolar transistors (common emitter/source, common base/gate, and common collector/drain) are analyzed and illustrated with real-world circuits. The analysis of multistage amplifiers (cascade amplifier, Darlington configuration, cascode amplifier, and differential amplifier) is also covered. 

Based on the transfer function, the computation of lower cutoff frequency is explained. Modelling of nonlinear capacitors is introduced. The corresponding small-signal model is provided and illustrated with the linearized diode model. Small-signal models of transistors valid from DC up to high frequencies are introduced. Miller's theorem is explained, and the upper cutoff frequency of transistor amplifiers is derived for all transistor orientations.  

This is followed by an introduction to noise modeling and analysis.  Based on the description of noise in the frequency domain (power spectral density), small-signal noise models of electronic components are introduced. These models are used in the calculation of the output noise of an amplifier. 

Knowledge of linear systems with negative feedback is complemented by root locus plots, Nyquist diagrams, and Nyquist stability criterion. Based on the latter, phase and gain margins are introduced. 

Last part of the course covers sinusoidal oscillators implemented as linear systems with positive feedback. The Barkhausen criterion is derived, and the location of poles of an oscillator is examined. The acquired knowledge is used for explaining oscillator startup and amplitude stabilization. Concrete examples of sinusoidal oscillators, such as phase-shift oscillators, LC oscillators, and quartz crystal oscillators, are discussed. 

The objective of the course is to provide students with essential knowledge required for the analysis, synthesis, and evaluation of linear electronic circuits. Students become familiar with linearization as a tool for analyzing linear circuits implemented with nonlinear components. They learn about transistor orientations and configurations used in linear circuits, the impact of capacitance on lower and upper cutoff frequency, fundamentals of noise analysis, the effects of feedback, the concept of circuit stability, and sinusoidal oscillators. Students gain practical experience by analyzing and measuring linear circuits. The course provides the theoretical foundation for discrete and integrated analog electronic circuit design.

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 of various linear circuits.