An Image-Reused Phase-Tuning mm-Wave QVCO with a FoM_T of -204 dBc/Hz

This paper presents an image-reused phase tuning technique (IPTT) for millimeter-wave (mm-wave) quadrature voltage-controlled oscillators (QVCOs). The phase shifter addresses the $-45^{\circ}-45^{\circ}$ phase rotation limitation, extending it to $135^{\circ}-225^{\circ}$. This enhancement extends the QVCO tuning range without deteriorating phase noise. To facilitate the expanded phase tuning range, a transformer-based fourth-order resonator providing bimodal impedance is employed in the proposed QVCO. The bimodal impedance ensures intra-band monotonicity and inter-band continuity, optimizing the overall tuning range. Mismatch mitigation and PLL integration of the proposed QVCO are also discussed. A prototype QVCO, operating from 31.6 to 49.2 GHz, is fabricated in a $40-\text{nm}$ CMOS process. Measurement results show that the QVCO consumes 10 mW of power and achieves a tuning range of $44 \%$ and phase noise of $-129 \text{dBc} / \text{Hz}$ at $10-\text{MHz}$ offset. This leads to a figure of merit $\left(\text{FoM}_{\text{T}}\right)$ of -204 $\text{dBc} / \text{Hz}$ at a $10-\text{MHz}$ offset.