A 17.4–26.4-GHz Dual-Injection Injection-Locked Frequency Tripler Featuring Low Power Consumption and High Harmonic Rejection

This paper presents a dual-injection injection-locked frequency tripler (ILFT) achieving wide locking range, high harmonic rejection and low power consumption. The injection voltage drives hard-switched tail transistors of the core oscillator as the first injection path, leveraging high injection strength for a wider locking range. The injection current is coupled to the core oscillator through an injection-current-boosting transformer in another injection path, which isolates the fundamental and the second-harmonic signals to improve the harmonic rejection property. An injection-locked buffer is cascaded to improve the output power flatness and further reject undesired harmonics. Fabricated in 65-nm CMOS process, the ILFT operates from 17.4 to 26.4 GHz with 41.1% locking range. Above 40-dBc harmonic rejection ratio within a 17.4 to 24 GHz bandwidth is achieved, and the power consumption of ILFT core is only 3.2 mW.