Integrated superregenerative amplifier based 24 GHz frequency modulated continuous wave radar active reflector tags for joint ranging and communication

Abstract

Concepts for two cooperative active reflector tags (ARTs) for joint ranging and communication in a linear frequency modulated continuous wave secondary radar system are presented along with corresponding theoretical derivations. To prove the concepts, the ARTs operating from 24 to 24.5 GHz are implemented using custom integrated superregenerative amplifiers (SRAs) designed in a 130 nm SiGe BiCMOS technology. The SRAs have a measured minimum detected input power greater than −80 dBm, and an output power greater than 3.2 dBm after wire‐bonding. The ARTs also feature roll invariance using bandwidth enhanced microstrip patch antenna diversity and a novel quench frequency shift keying based low data rate simplex communication. Indoor ranging experiments done to prove the concepts and the theoretical considerations show a maximum distance of 77 m in the ranging mode and a data rate of 0.5 symbols per second in the data transfer mode. For distances less than 5 m, the characterised accuracy is better than 12 cm and the precision is better than 2 cm. To the best of authors' knowledge this is one of the first reported scientific works leading to a proof of concept for integrated superregenerative amplifier based joint ranging and quench frequency shift keying. The combination of maximum range and precision are also one of the best reported among similar works in the literature.