A 127–140GHz injection-locked signal source with 3.5mW peak output power by zero-phase coupled oscillator network in 65nm CMOS

A high output power and high efficiency injection-locked millimeter-wave (mm-wave) signal source is demonstrated by zero-phase coupled oscillator network (CON) at 140GHz. Each oscillator unit-cell is designed by an inter-digital coupler with zero-phase shift and 0.4dB loss at 70GHz, and is further doubled to 140GHz by a push-push frequency doubler. With four in-phase coupled unit-cells, high output power 140GHz signal is generated at the center of the CON by an in-phase power combination of the second harmonics generated by push-push frequency doublers. Moreover, a 9.7% frequency-tuning-range (FTR) centered at 133.5GHz is achieved by inductive tuing at each oscillator unit-cell. The proposed mm-wave signal source is farbicated in 65nm CMOS process with compact core chip area of 0.13mm². The measured results are: 3.5mW peak output power, 2.4% power efficiency and 26.9mW/mm² power density.