Ku-Band Low Phase Noise VCO Using High-Quality Factor Transformer in 0.18-μm CMOS Technology

Abstract

This work introduces a low phase-noise (PN) wideband voltage-controlled-oscillator (VCO) by proposing five ports transformer in 0.18- $\mu \text{m}$ CMOS technology. The proposed VCO uses five ports transformer and operates in the low band when all the pMOS–nMOS cross-coupled VCO components are activated, whereas this VCO operates in the high band using only part of the transformer, and an nMOS cross-coupled core. The transformer is designed using the top metal layer (M6) and the first inductor is meander line U-shaped center tap inductor, while the second inductor consists of two shunted octagonal loops to increase the quality ( ${Q}$ -) factor compared with using a single-loop inductor. The wideband switched transformer VCO achieves a measured frequency tuning range (FTR) of 16.4–17.1 GHz with a PN of −113.3 dBc/Hz at 1-MHz offset, and from 17 to 17.9 GHz with a PN of −110.3 dBc/Hz at 1-MHz offset in the low and high bands, respectively. The achieved figure-of-merit (FoM) is −189 and −186.4 dBc/Hz in the low and high bands, respectively.