A Hybrid Class-B/C Mode-Switching VCO With 80% Current Efficiency and 202.2 dBc/Hz FoMT

Abstract

In this article, an innovative class-B/C hybrid mode-switching technology is proposed, which can significantly improve the frequency tuning range (TR) and current efficiency of the voltage-controlled oscillator (VCO). Using the proposed technology, the class-B current in the traditional mode-switching VCO is replaced with the more efficient class-C current, thereby optimizing the power consumption and steady-state performance of the VCO. In addition, the use of a negative resistance structure with an opposite temperature coefficient improves the VCO's robustness to process, voltage, and temperature (PVT), especially to temperature changes. Thanks to the introduction of the low harmonic distortion of the class-C core and the source degeneration resistor, the flicker noise of the transistor and the phase noise (PN) of the VCO have been further improved. The VCO is designed and laid out in 65-nm complementary metal-oxide-semiconductor (CMOS) technology, with a total area of 0.12 ${\text{mm}}^2$.The postsimulation TR is 41.3% from 12.6 to 19.1 GHz. The PN and figure of merit turning ( ${\text{FoM}}_T$) at 1-MHz offset are −113.2 and 202.2 dBc/Hz, respectively. The VCO consumes only 3.36 to 3.58 mA of current under a 1.2 V power supply, while maintaining an 80% current efficiency, which is significantly higher than the 63.7% of typical Class-B VCOs.