🔷 Block Diagrams & Signal Flow

Block Diagrams

A block diagram represents a system as a set of functional blocks connected by signals (arrows). Each block has a defined transfer function — the mathematical relationship between its input and output.

Block diagrams are used to:

• Visualize system structure and signal flow
• Identify interfaces between subsystems
• Calculate overall system gain or transfer function
• Analyze stability and performance

Series Blocks (Cascade)

When blocks are connected in series, the output of one feeds the input of the next. The overall gain is the product of individual gains:

G_total = G₁ × G₂ × G₃ × ...

Example: amplifier (gain 10) → filter (gain 0.5) → output stage (gain 4) → total gain = 10 × 0.5 × 4 = 20

Parallel Blocks

When the same input goes to multiple blocks whose outputs are summed, the overall gain is the sum of individual gains:

G_total = G₁ + G₂ + G₃ + ...

Summing Junctions and Branch Points

• Summing junction: A circle with "+" or "−" signs where multiple signals are added or subtracted
• Branch point (pickoff point): Where a signal splits to feed multiple paths — the same value goes to each path