Fundamentals of Analog Electronics and Semiconductors

Sep 28, 2024

Analog Electronics Lecture Notes

Introduction to Analog Electronics

  • Begin with semiconductor materials: the backbone of electronic devices and circuits.
  • Course covers:
    • Bipolar Junction Transistors (BJT)
    • Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET)
    • Junction Field-Effect Transistors (JFET)
    • Operational Amplifiers (OPAMP)

Conductors, Insulators, and Semiconductors

Conductors

  • Conductors support a generous flow of charge with applied voltage.
  • Examples: Copper wire, Aluminum wire.
  • Formula for cross-sectional area: A = πr².

Insulators

  • Low conductivity; flow of charge is nearly zero.
  • Examples: Mica, Wood.
  • Mica used for thermal and electrical insulation.

Semiconductors

  • Conductivity between that of conductors and insulators.
  • Examples: Silicon (Si) and Germanium (Ge).

Resistivity

  • Represented by ρ (rho), reciprocal of conductivity (σ).
  • Formula: ρ = RA/L (where R is resistance, A is area, L is length)
  • Units: Ohm meter (Ω·m).

Resistivity Values

  • Conductor (Copper): 10^-6 Ω·cm.
  • Insulator (Mica): 10^12 Ω·cm.
  • Semiconductor (Silicon): 50 x 10³ Ω·cm.

Energy Band Diagram

Key Concepts

  • Isolated Atom: Nucleus with neutrons/protons surrounded by electrons in orbitals.
  • Valence Band & Conduction Band: Outermost orbit splits in lattices.
  • Energy Band Gap (Forbidden Band Gap): Energy needed to move electrons from valence to conduction band.
    • Insulators: ~6 eV gap.
    • Semiconductors: ~1 eV gap (Germanium: 0.75 eV, Silicon: 1.16 eV).
    • Conductors: Overlapping valence and conduction bands.

Periodic Table Position

  • Silicon and Germanium in Group 4 (4 electrons in outermost orbit).
  • Aim for noble gas configurations (Silicon: Argon, Germanium: Krypton).

Crystal and Lattice Structures

  • Silicon and Germanium atoms form crystal structures through covalent bonds.
  • Covalent bonds share electrons to achieve stable electron configurations.

Upcoming Topics

  • Intrinsic and Extrinsic Semiconductors.
  • Electron and Hole concept.

These notes summarize the essential topics from the lecture on analog electronics and semiconductor materials. Future lectures will delve deeper into semiconductor concepts.