ESD protection diodes for USB4 and Thunderbolt ensure signal integrity beyond 10GHz

Nexperia has introduced a new series of five high-performance protection 1V diodes that provide optimised protection for AC-coupled RF transmission lines against ESD events, surge currents and short circuit conditions. These diodes – examples include the PESD1V0C1BSF and PESD1V0H1BSF – are perfect for safeguarding USB4 and Thunderbolt interfaces found in various applications, including cellular handsets, portable electronic devices, communication systems, and computers and other peripherals.

As data rates for USB4 and Thunderbolt interfaces exceed 10GHz, ESD protection must provide superior RF performance while effectively guarding sensitive ICs against ESD events and surge pulses, especially those caused by potential short circuits between Vbus and TX/RX in non-compliant USB Type-C interfaces. The optimal choice of ESD protection device depends on the individual PCB layout. While boards with shorter traces between the transceiver IC and the protection device benefit from lower parasitic inductance, this has the unintended consequence of reducing overall system-level ESD robustness. On the other hand, boards with longer traces have fewer clamping issues (due to the increased inductance), but signal integrity issues can become a concern.

"With this new series of protection diodes, Nexperia provides designers with the flexibility to select the device that is most appropriate to their specific board layout and thereby offering the highest level of protection," says Stefan Seider, senior product manager at Nexperia. "Nexperia can also offer RF and SEED (ESD) simulation models to optimise the device choice."

These diodes can protect USB4 and Thunderbolt interfaces against ESD events up to +/-18kV while delivering best-in-class surge robustness (up to Ipp= 9.6A average). The ultra-low device capacitance (down to 0.1pF) of these diodes, housed in the company's industry-proven tiny leadless ultra-low inductance DSN0603-2 (SOD962-2) package, means they also benefit from minimal insertion losses (down to -0.21dB @ 12.8GHz) without any resonance up to 40GHz.