Active Isolation Structure for Directional Stress Current Injection

Abstract

In the testing of high-speed interfaces for electrostatic discharge (ESD)-induced soft failure susceptibility, for example, using a transmission-line pulse (TLP), the current propagates toward both ends of the channel from the injection point, resulting in the inability to determine if the host or the device under test (DUT) failed. Unidirectional current injection toward the DUT is necessary. An active circuit design is proposed for unidirectional current injection in high-speed simplex interfaces. The proposed method is applied to a USB3 Gen 1 interface. To verify the effectiveness of the proposed unidirectional injection structure, directionality, gain flatness, and maximum stress level are measured. Eye diagram simulation results verify the negligible electrical impact of the proposed isolating structure.