A 148-GHz Radiator Using a Coupled Loop Oscillator With a Quad-Feed Antenna in 22-nm FD-SOI

• Published in: IEEE journal of solid-state circuits Vol. 56; no. 5; pp. 1514 - 1526
• Main Authors: Mansha, Muhammad Waleed, Hella, Mona M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna; Antennas; CMOS; Configurations; Couplings; effective isotropic radiated power (EIRP); efficiency; injection locking; Integrated circuits; Lenses; millimeter-wave (mmWave); Oscillators; Power generation; Radiators; Signal injection; Slot antennas; SOI; Substrates; terahertz (THz); voltage-controlled oscillator (VCO)
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2021.3066121

This article presents a 148-GHz coupled loop fundamental oscillator with a quad-feed octagonal slot antenna. The proposed loop configuration with a multi-feed antenna leads to each oscillator experiencing multiple injected signals. An analysis is performed to explain the dynamics of the coupled loop oscillator in the presence of multiple signal-injection paths. It is shown that the proposed oscillator configuration will only operate with <inline-formula> <tex-math notation="LaTeX">- \pi /2 </tex-math></inline-formula> phase between the adjacent oscillators. This phase difference is necessary for the quad-feed antenna to combine and radiate the output power from the four single-ended oscillators in the loop. The output from each oscillator is ac coupled to the following oscillator stage using a phase compensating capacitor, whose value is selected to enhance the oscillation frequency of the coupled loop. The use of buffer stages is avoided in favor of a passive power feed network for extraction of the output power from each oscillator. The proposed oscillator is fabricated in a 22-nm FDSOI process and has a 0.5-mm 2 chip area. The measured peak effective isotropic radiated power (EIRP) of the oscillator is 9.7 dBm with a corresponding dc-EIRP efficiency of 34.3% when operating from a 0.8-V supply. To the authors' knowledge, this dc-EIRP efficiency is the highest among reported oscillators to date operating between 100 and 200 GHz.