CMOS integrated galvanically isolated RF chip-to-chip communication utilizing lateral resonant coupling

Abstract

In this work, a high voltage (HV) galvanically isolated chip-to-chip communication circuit utilizing laterally coupled resonators is reported. The adjacently placed resonators provide high voltage galvanic isolation (GI) using horizontal space between resonators filled with oxide, which minimizes the need for thick inter-metal dielectrics. A previously unexplored application for lateral coupling is introduced as a passive communication channel for GIs. Magnetic coupling between resonators is used to transfer an upconverted digitally-modulated OOK control signal at 2.8 GHz through the galvanic isolator. This proposed method can be integrated using CMOS processes, without altering the native process or adding extra fabrication steps. The system is realized in a 0.25 µm BCD (Bipolar-CMOS-DMOS) process with only four metal layers for proof of concept. The design does not require exotic packaging and provides 3.3kV RMS isolation, small physical area of 0.95mm2, and sub-20ns propagation delay. The implemented resonators inherently act as bandpass filters, thus enhancing circuit noise immunity to common mode transients.