A 40.6% Tuning Range Low-Phase-Noise Class-F-1/3 VCO Using Simultaneous Frequency and Harmonic-Mode Switching

In this brief, the method of simultaneous frequency band and harmonic-mode switching is proposed to maintain broadband low phase noise (PN) performance in transformer-based harmonic-shaping voltage-controlled oscillators (VCOs). The switched-capacitor arrays used for frequency band switching are multiplexed to achieve harmonic-mode switching, which enables the current-reuse VCO to operate in class- F-1 and class-F-3 modes at high- and low-band, respectively. Compared with manual harmonic tuning methods, the proposed method avoids the use of additional lossy harmonic tuning capacitors. The class- F-1/3 VCO is inherently area-efficient. The proposed VCO is fabricated in a 110-nm CMOS process. The measured frequency tuning range (FTR) is 6.18 similar to 9.33 GHz (40.6%). Thanks to dual-mode operation, the measured peak PN is -122.4 dBc/Hz at 1-MHz offset, and the FoM is 186.1 similar to 188.0 dB over the FTR. A -200.1 dB peak FoM with FTR (FoM(T)) is achieved.