ESD mm-Wave-Circuit Protection: 3-dB Couplers

This article presents an innovative architecture for the implementation of an electrostatic discharge (ESD) protection for millimeter-wave (mm-wave) devices. The proposed architecture is based on the use of 3-dB couplers, whose coupled outputs have been shorted to the ground node. In order to reduce the physical dimensions of the 3-dB coupler and to reach the high coupling required for this application, the Coupled Slow wave CoPlanar Waveguides (CS-CPWs) architecture was favored. The demonstrator of the proposed system was fabricated in the STMicroelectronics 55-nm bipolar-cmos (BiCMOS) technology, demonstrating a return loss greater than 10 dB across the 50–160-GHz frequency range, an attenuation greater than 18 dB below 5 GHz, and a minimum insertion loss at 90 GHz of 0.55 dB. To prove the performance of the proposed solution, human body model (HBM) and charge device model (CDM) events were simulated at the input of the 3-dB coupler, showing that the proposed architecture effectively protects against these events while minimally impacting the RF path.