On the design and characterization procedure of 300-GHz slotline-coupled oscillators in CMOS

This contribution reports on a submillimeter-wave source consisting of two mutually coupled harmonic oscillators in CMOS that emit coherent radiation at 300 GHz. The unitary oscillator cell uses a differential self-feeding topology which incorporates an on-chip integrated folded-slot antenna for second-harmonic radiation. To increase the radiated power, two free-running oscillator units are injection-locked by each other through their respective slotline resonators. In this case, a standing wave is sustained across the array with a virtual short circuit at the connection point. Both, the single and the two-coupled oscillator were prototyped in commercial 65-nm CMOS technology. In combination with a silicon lens, the measured samples produced linear-polarized radiation above 290 GHz with frequency tunability exceeding 10 GHz and 6 GHz for the single and the double oscillator designs, respectively.