A new transformer-coupled differential Armstrong VCO for very low power operation

We present a novel differential Armstrong VCO. The proposed Armstrong VCO adopted a new transformer structure which effectively enhanced the output voltage swing of the VCO. The Armstrong VCO was implemented in 0.13 μm RF CMOS process, and measurement showed the oscillation frequency range from 13 to 14.5 GHz (tuning range of 10.9%). The new Armstrong VCO achieved a measured phase noise performance of -104.6 dBc/Hz at 1 MHz offset from 13.66 GHz carrier. The figure-of-merit (FOM) shows excellent performance and the results demonstrate a potential of the novel Armstrong VCO structure for achieving a good phase noise performance.