Differential Retrodirective Array With Integrated Circuits in Low-Cost 0.18 μm CMOS for Automatic Tracking

This communication presents a differential retrodirective array (RDA) for real-time tracking. The proposed differential RDA consists of three phase-conjugating chips and two circularly polarized antenna arrays. The phase-conjugating circuit chip, which is in
$0.18~\mu \text{m}$
CMOS process, includes a differential low-noise amplifier, a double-balanced mixer, and a differential power amplifier. The specifically designed chip consumes 38.4 mW with a low voltage supply of 1.2 V. Experimental results of monostatic and bistatic cases show that the RDA has a 3 dB beamwidth up to 77°. To the best knowledge of the authors, the proposed RDA with circular polarization, which is promising for tracking free-moving targets, is the first differential RDA enabled by specifically designed low-cost CMOS chips.