Gas Discharge Tubes (GDTs)

Function: Protect circuits against high-voltage transients (e.g., lightning, ESD) by ionizing gas to create a low-resistance path to ground.

Key Features:

• • High surge current handling (kA range)
• • Low capacitance (<1pF), ideal for high-frequency lines
• • High insulation resistance when off
• • Slow response time (~μs)

Applications: Telecom lines, RF systems, power entry protection, hybrid protectors (with TVS diodes).

Common Configurations: Two-electrode (line-ground), three-electrode (line-line-ground).

Limitations: Follow-on current in AC; may require current-limiting elements.