Power Amplifiers (PA)

1. Conceptual Intuition (L1)

• The "Muscle" of the radio.
• Efficiency: Trading battery life for signal quality.
• Analogy: The engine throttle (Class A runs at full RPM always, Class B idles).

2. Engineering Math (L2)

• PA Classes:
  • Class A (Linear, Inefficient, 360 deg conduction).
  • Class B/AB (Compromise, Push-pull).
  • Class C (Pulses, tuned load).
  • Class D/E/F (Switching modes, theoretical 100% eff).
• Output Power ($P_{out}$), Power Added Efficiency (PAE).

3. System Application (L3)

• Linearity vs Efficiency Trade-off.
• Spectral Regrowth (ACPR) due to nonlinearity.
• Digital Pre-Distortion (DPD) concepts.
• Thermal management.

Interactive Component: Load Line Visualizer

• Description: Visualize where the transistor operates on the I-V curve.
• Controls: Bias Point, Input Drive, Load Impedance (Load Pull).