I hope you enjoyed reading and studying this book. It includes quite a lot of basics for electronics, mainly targeting analog circuits and analog systems. The main topics include a short introduction into the non-linear components that are crucial for the vast majority of useful electronic circuits: the transistors. Their non-linear behavior enables them to perform useful operations but that same non-linear behavior makes it quite hard to analyze analytically and hence to grasp the operation of circuits. That’s where separating transistor behavior in a (DC or quasi-DC) bias point behavior and into their behavior as a response to small signal excitations about that operating point comes in.
This was leveraged to analyze, synthesize and design amplifier circuits, with and without feedback. Stability issues of feedback systems are treated as well as creating stably oscillating (harmonic) oscillator circuits that you may use as frequency reference in e.g. analog-to-digital converters, in digital-to-analog-converters. And finally this book provides an outlook towards circuits operating at high frequencies (radio frequencies), which shows that then you need to model e.g. wires and that Kirchhoff’s voltage and current laws do not hold anymore. Luckily, Maxwell does hold. And luckily under some assumptions using Kirchhoff’s laws is still fine. This outlook allows you to understand the basics of radio systems: systems that transmit and/or receive signals wirelessly.
Again, I sincerely hope you did learn a lot and that you enjoyed the very interesting and world-shaping field of electronics.