Electronic Devices & Circuits

This is a complete, web-native course in Electronic Devices and Circuits for second- and third-year undergraduates in electrical and electronics engineering. Its thirty chapters run from what a silicon crystal is doing before any junction exists, through to a regulated supply and a working oscillator. Each chapter lives on its own page — readable on any device, linkable, searchable and free to share.

Nothing on these pages is decorative or borrowed. Every figure is drawn inline as SVG in the page itself — every band diagram, characteristic curve, circuit schematic, waveform and Bode plot — so it scales to any screen, prints cleanly, carries a written description for a reader who cannot see it, and cannot go missing the way an image file can. Every numerical result is computed rather than quoted: each carrier concentration, ripple factor, bias point, gain, break frequency and efficiency figure was evaluated before it was written down, which is why the numbers here do not always match the rounded ones printed in textbooks.

The six parts follow the order in which the subject has to be learnt. Part 1 is the physics — bands, doping, the Fermi level, drift and diffusion, and the junction in equilibrium, without which the diode equation is just a formula to memorise. Part 2 is one junction put to work: rectification, filtering, wave shaping and regulation, with the four figures of merit that decide whether a supply is any good. Part 3 covers the junctions engineered away from rectification — Schottky, varactor, tunnel, optoelectronic and four-layer devices. Parts 4 and 5 are the transistors, bipolar and field-effect: how each one works, how its operating point is placed and held, and how the small-signal model turns a curved characteristic into a linear amplifier. Part 6 puts them together — cascading and frequency response, the operational amplifier and the circuits built around it, active filters, oscillators and voltage regulators.