A Millimeter-Wave Standing-Wave Oscillator With Frequency-Specific Wave-Velocity Control Demonstrating Class-F Effects

Abstract

Implementing dual-resonance class-F oscillators with transformer feedback beyond 60 GHz poses significant challenges due to the limited third-harmonic tank impedance when using small coils with low coupling factors. To address these limitations and leverage the phase noise advantages of class-F operation, this letter introduces a standing-wave oscillator (SWO) topology featuring an on-chip multiband transmission-line (t-line) resonator loaded with harmonically tuned open stubs. The proposed design enhances third-harmonic resonance while facilitating precise alignment of the oscillation frequencies. Three voltage-controlled oscillators (VCOs) were implemented using TSMC’s 65-nm LP technology, demonstrating that the proposed class-F half-wavelength SWO achieves phase noise improvements of 3.1 and 6.4 dB at a 1-MHz offset compared to conventional SWO and transformer-based class-F VCO, respectively.