A 0.53-THz Subharmonic Injection-Locked Phased Array With 63- <tex-math notation="LaTeX">μ </tex-math> W Radiated Power in 40-nm CMOS

This paper presents a 0.53-THz subharmonic injection-locked 1 × 4 phased array based on an injection-locked oscillator (ILO) chain. Thanks to the ILO chain, the phase errors in the phased array can be compensated without introducing power variation. This technique enables accurate beam steering with a 60° scan range in the E-plane at 0.53 THz. A sixstage triple-push oscillator is proposed to generate the signal at 0.53 THz. Compared with a conventional triple-push oscillator, it reduces layout constraints, improves signal balance, and enhances output power by at least 3 dB. The phased array is implemented in 40-nm CMOS. With an injection power of 0 dBm, the injection-locked phased array generates an output frequency from 529 to 534 GHz. At 531.5 GHz, the proposed phased array achieves -12-dBm radiated power and 0.24 0 / 00 dc-to-terahertz (THz) efficiency without the use of silicon lens, quartz superstrate, or substrate thinning. The chip consumes 260-mW dc power and occupies an area of 2.5 mm 2 .