Design of a switched injection-locked oscillator as an active backscatter transponder for a 2.45 GHz FMCW radar system

This paper presents a fully integrated active backscatter transponder for the use in a FMCW radar system for localization of passengers in sea in case of a ship sinking emergency. The active reflector tag is based on a cross-coupled oscillator circuit topology operating as a switched injection-locked oscillator (SILO). The circuit was implemented in a 180nm BiCMOS technology. Measurements resulted in an output power of 12.6dBm while consuming a DC power of 69mW, thus achieving a high efficiency of 26 %. Furthermore, the frequency tuning range is 18 %, the start-up time is 5.5 ns and the input referred noise power was measured to -79 dBm.