A 22.8–26.0-GHz VCO With Discriminative-Harmonic-Current-Manipulating for Phase Noise Improvement

A discriminative-harmonic-current-manipulating (DHCM) technique is proposed to improve the phase noise (PN) of high-frequency voltage-controlled oscillators (VCOs). Superior PN performance has been demonstrated by conventional multi-resonance VCOs when they are equipped with appropriately tailored tank impedance. However, meticulous alignment of the impedance peaks is typically required through manual tuning, particularly at high frequencies. In this work, the 3rd harmonic voltage, crucial for reshaping the impulse sensitivity function (ISF), is sustained by substantially boosting the 3rd harmonic current. Meanwhile, the 2nd harmonic current, identified as causing high ISF sensitivity and consequent noticeable PN fluctuations, is drastically suppressed. By selectively manipulating these harmonic currents, the rigorous requirement on the concurrent multiple impedance peaks is alleviated, thereby enabling a tuning-free multi-resonance oscillation. The DHCM VCO prototyped in a 65-nm CMOS process measures a tuning range of 22.8–26 GHz and PN of −134.6 dBc/Hz at 10-MHz offset, while consuming dc power of 7.3–9.7 mW from a 0.6-V supply. The figure-of-merit (FoM) and FoM with tuning range (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {FoM}}_{T}$ </tex-math></inline-formula>) achieved are up to 193.8 and 196.3 dBc/Hz, respectively. The core area occupied is 0.12 mm2.