Design Techniques for Load-Independent Direct Bulk-Coupled Low Power QVCO

Design techniques for a load-independent low-power low-phase-noise CMOS LC direct bulk-coupled quadrature voltage-controlled oscillator (DBC-QVCO) is presented in this paper. A capacitor tapping technique is used to lower the phase noise and achieve load-independent frequency of oscillation. Class-C operation is used to further reduce the phase noise and power consumption. Quadrature coupling is achieved using bulk coupling, leading to reduction in both power and area. The DBC-QVCO has been implemented in a standard 0.18-μm BiCMOS process and occupies an area of 0.3 mm
²
. The implemented DBC-QVCO achieves a measured phase noise of -114.2 dBc/Hz at 1-MHz offset from the 6.26-GHz carrier while consuming only 3.2 mW from a 1-V power supply. The DBC-QVCO achieves a figure of merit (FOM) of -185.1 dBc/Hz and an FOM with area of -190.3 dBc/Hz, which are among the best compared with recently published QVCOs operating in a similar frequency range.