A Reconfigurable Compact Multiband RF Bi-directional Coupler for sub-6 GHz RF Front-Ends in RF SOI CMOS Switch Technology

In this work, a radio-frequency (RF) bi-directional coupler with tunable operating frequency is presented. To cover the entire sub-6 GHz spectrum, the directivity is optimized for different frequencies with the proposed digitally controlled-tuning network by compensating the frequency dependency of the coupling components and the degradation induced by parasitics. The tuning network with an inductive component and its area-efficient design is proposed. The device is implemented in 90 nm RF SOI CMOS switch technology. The designed tuning network allows the coupler to have a directivity of over 30 dB from 700 MHz to 6 GHz with a power consumption of only 29 µW. An input-referred third-order intercept point (IIP3) of 110 dBm is reached for the signal through the transmitted path.