A 1.5-5-GHz Integrated RF Transmitter Front End for Active Matching of an Antenna Cluster

A recently proposed method for realizing frequency-reconfigurable antennas across a wideband is based on adjusting the feed amplitudes and phases of a multiport antenna. In this article, we demonstrate the feasibility of the method, for the first time, with a conjunction of an integrated RF transmitter and a four-element antenna cluster. The implementation performs on-chip amplitude and phase tuning with supply scaling and delay tuning circuits to tune the antenna cluster without requirement of matching network. The antenna cluster is built with four closely spaced antenna elements implemented on a printed circuit board. The transmitter integrated circuit (IC) is implemented in a 28-nm CMOS process with the chip size of 0.85 mm $\times0.95$ mm, including pads. The proof-of-concept implementation demonstrates tunability across a wideband from 1.5 to 5 GHz.