Current reused VCO using stacked transformer and self body bias structure

This article presents a self-body-bias current reused VCO with stacked transformer. The transformer is designed to improve the output symmetry and enlarge the swing also saves more chip area by stacking the two coils. In order to extend the tuning frequency, the primary coil of the transformer has a small inductance. Since the core structure is a current reused circuit, a modified adaptive body-bias is used. The self-body-bias structure provides two different feedback swings with small voltage deviation to the core transistors. The proposed VCO is deigned to achieve IEEE 802.11a application, the frequency can be tuned from 4.672GHz to 6.238GHz, where the tuning voltage is 0~2V The phase noise is -118.524dBc/Hz and core power is 6.102mW.