A K-Band VCO using a Transformer-Based Resonance Tank for Biomedical Radar Applications

This paper presents a millimeter-wave widetuning range voltage-controlled oscillator (VCO) fabricated using the TSMC 90-nm CMOS process. A low phase noise (PN) and wide-tuning range performance can be achieved by utilizing a noise filter inductor and a transformer-based resonator. The transformer-based resonator increases the tuning range by doubling the bias range of the varactor and boosts the quality factor of the resonator tank through impedance transformation. A 2-bit capacitor bank is also used to achieve reasonable VCO gain (Kvco). The proposed VCO achieves a $\mathbf{2 7. 5 \%}$ tuning range of $19.5-25.8 \text{GHz}$ while consuming 7.9 to 8.6 mW. It realizes a phase noise of $\mathbf{- 1 0 2. 6} \mathbf{\ d B c} / \mathbf{H z}$ at a $1 \mathbf{\ M H z}$ offset and a figure of merit with a tuning range $\left(\text{FOM}_{\mathrm{T}}\right)$ of $\mathbf{- 1 8 9. 5 \text{ dBc } / \text{ Hz } \text {. }. \text {. } \text{ d }}$