The Capacitance Dilemma at Multi-Gigabit Speeds
Standard TVS diodes exhibit parasitic junction capacitance between 5pF and 50pF. At high frequencies (such as USB 3.2 Gen 2 at 10Gbps or HDMI 2.1 at 48Gbps), this capacitance rounds signal square waves, causing severe eye closure and packet loss.
Specifying Ultra-Low Capacitance TVS Arrays:
- For USB 2.0 (480Mbps): Diode capacitance < 3.0pF is sufficient.
- For USB 3.2 / PCIe 3.0: Diode capacitance must be < 0.5pF.
- For Thunderbolt 4 / HDMI 2.1: Use specialized silicon arrays with parasitic capacitance < 0.2pF to preserve impedance matching.