A dual wideband and low phase-noise CMOS voltage-controlled oscillator with a transformer-based switching resonator

This work presents a dual-band CMOS voltage-controlled oscillator (VCO) design by using a pair of transformers as part of a switching resonator for band selection. The proposed design is characterized mainly by its ability to achieve two separate wide tuning bands. Additionally, the VCO phase noise is significantly diminished by applying the impedance locus method. Consequently, the dual-band VCO has a tuning range of 2.3 to 3.2 GHz for the low-band mode and 4.29 to 5.35 GHz for the high-band mode. The measured phase noises are -125 dBc/Hz and -123 dBc/Hz for the low-band and the high-band, respectively, at the frequency offset of 1 MHz. This dual-band VCO is implemented using 0.18 μm CMOS technology with a supply voltage of 1.8 V.