A 20.65-to-40.55 GHz Dual-Core Quad-Mode VCO With Mode-Independent Transformer-Switching Technique in 65-nm CMOS

This brief proposes a dual-core quad-mode millimeter-wave (mm-wave) voltage-controlled oscillator (VCO) using a compact multi-mode LC network with a mode-independent switched transformer technique. On top of the dual-mode main LC tank, the mode-independent switched transformer technique introduces two additional oscillation modes, further extending the frequency tuning range with a small chip area overhead, while the mode-independent feature reduces the cost of switch off-capacitance compared with the conventional switched transformers. Implemented in 65nm CMOS process, the proposed VCO achieves a measured octave frequency tuning range from 20.65 to 40.55 GHz. The measured best phase noise is -131.04 dBc/Hz at 10 MHz offset from 20.65 GHz. The measured best figure-of-merit (FoM) is 187.25 dBc/Hz at 10 MHz offset from 26.66 GHz, corresponding to a figure-of-merit of tuning range and area (FoM textsubscript TA) of 216.72 dBc/Hz thanks to the proposed compact multi-mode LC network and the mode-independent switched transformer technique. The VCO consumes 9.75-to-18.85 mW from a 0.65 V supply voltage. The core area is 0.048 mm2.