CMOS QVCO With Current-Reuse, Bottom-Series Coupling, and Forward Body Biasing Techniques

Abstract

This letter presents an LC-tank quadrature voltage-controlled oscillator (QVCO) using bottom-series coupling, forward body biasing, and current-reuse techniques. The bottom-series coupling to generate the quadrature signals enhances the phase noise performance. The forward body biasing of the switching and coupling transistors is used to alleviate the voltage headroom issue for stacked transistors. In addition, the current-reuse technique reduces the current consumption. A phase shift analysis for QVCOs introduces how to choose device sizes for a better Q-factor of the LC-tank. The proposed QVCO showed a phase-noise figure-of-merit of -190.9 dBc/Hz and a frequency tuning range from 5.80 to 6.44 GHz, while having a low power consumption of 2 mW for the core QVCO from a supply of 1.05 V.