Critical Area Analysis (CAA), Morphological Dilation & TVS Protection

1. Critical Area Analysis (CAA)

Critical Area Analysis (CAA) is a yield modeling technique used to quantify the layout area where a defect can cause a circuit failure (short or open).

Y = exp(-D₀ · Ac)

Larger critical area leads to lower yield.

Short CAA Concept (Defect Bridging)

Metal 1 Metal 2 Critical Area (Overlap) Expanded by defect radius (r)

2. Morphological Dilation

Morphological Dilation expands a polygon outward by a defined distance r.

A ⊕ B

Dilation Example

Original Polygon (A) r Dilated Region: All points within distance r

3. TVS (Transient Voltage Suppressor) Protection

A TVS diode protects sensitive circuits from transient voltage spikes by clamping excessive voltage and diverting surge current to ground.

When V > VBR → Avalanche conduction → Surge diverted to GND

During normal operation, the TVS remains off. When a transient spike occurs, it rapidly conducts and clamps the voltage.

TVS Protection Diagram

↩ Go to Home – Tech Notes Park