A CMOS Data Transfer System Based on Planar RF Coupling for Reinforced Galvanic Isolation with 25-kV Surge Voltage and 250-kV/µs CMTI

Abstract

This paper exploits an effective approach to overcome the breakdown limitations of traditional galvanic isolators based on chip-scale isolation barriers, thus achieving a very high isolation rating (i.e., compliant with the reinforced isolation requirements). Such an approach is based on radio frequency (RF) planar coupling between two side-by-side co-packaged chips. Standard packaging along with proper assembling techniques can be profitably used to go beyond 20-kV surge voltage without using expensive or exotic isolation components. As a proof of concept, a bidirectional data transfer system based on RF planar coupling able to withstand an isolation rating as high as 25 kV has been designed in a low-cost standard 0.35-µm CMOS technology. Experimental measurements demonstrated a maximum data rate of 40 Mbit/s using a carrier frequency of about 1 GHz. The adopted approach also guarantees a common mode transient immunity (CMTI) of 250 kV/µs, which is a first-rate performance in view of next generation galvanic isolators for wide-bandgap power semiconductor devices, such as gallium nitride high-electron mobility transistors (GaN HEMTs) and silicon carbide (SiC) MOSFETs.