CMOS fully integrated quasi‐circulator with self‐interference cancellation technique

Abstract

In this Letter, the authors propose a novel fully integrable architecture for a quasi-circulator. It is comprised of an inductorless and wideband structure and off-chip components are not required. This solution is appropriate for use in backscattering systems, such as RFID-tag readers. The proposed quasi-circulator differs from passive off-chip circulators because the power amplifier is embedded and the terminals have non-standard impedances. Thus, they propose a leakage figure as a figure-of-merit, which is related to the isolation of conventional circulators. The structure described herein is applied to a wireless power transfer system with an output power of 25 dBm at 990 MHz.