A Fully Integrated 263-GHz Retro-Backscatter Circuit with 105° Reading Angle and 12-dB Conversion Loss

This paper presents the first fully integrated on-chip sub-THz retro-backscatter CMOS circuit, specifically operating at 263~GHz. Using the Van Atta reflector principle, the design achieves retro-directive operation with an angle availability of 105$^\circ$. An electromagnetic (EM) switch pair is proposed to reduce the usage of transistor-based switches. Fabricated in an Intel-16 CMOS process, the prototype demonstrates stable BPSK modulation over an input power range of -7~dBm to -13.9~dBm at 263~GHz, exhibiting a measured conversion loss of 12 dB. These findings validate a low-cost, low-power, wide-angle THz retro-backscatter solution, paving the way for energy-efficient IoT networks and emerging high-frequency RFID applications.