Dual Band Quadrature VCO Using Switched-transformer Coupling for Wireless Robot Applications

A dual band QVCO using switched transformer coupling is proposed. The proposed QVCO comprises two complementary cross-coupled dual-resonance VCOs and 4 switched-transformers in a ring for coupling the two differential VCOs to generate the quadrature outputs. The measured phase noise at 1MHz offset frequency from 2.41 GHz and 3.08 GHz carrier are -121.4 dBc/Hz and -113.9 dBc/Hz. Tuning range of VCO is 0.39 GHz and 0.61 GHz, from 2.41 GHz to 2.8 GHz and 2.83 GHz to 3.44 GHz while the control voltage was tuned from 0V to 2V. The VCO occupies a chip area of 1200×1200μm
²
and the figure of merit of -181.8 dBc/Hz and -173.7 dBc/Hz while consuming 5.2mW and 9.7mW power, implemented in TSMC 0.18 μm 1P6M CMOS process for wireless robot applications.