A low phase-noise 24GHz CMOS quadrature-VCO using PMOS-source-follower coupling technique

An effective coupling topology for multi-phase oscillators is proposed and demonstrated in a standard 90nm CMOS technology. Compared with the conventional parallel or series coupling methods, the PMOS-source-follower coupled (PSFC) technique with the coupling transistors operated in the cut-off region can significantly reduce the flicker noise and hence the phase noise of VCO. The proposed PSFC QVCOs at 24.39GHz demonstrates a low phase noise of -106.05dBc/Hz at 1MHz offset with a tuning range of 3.22GHz under the supply voltage and current consumption of 1V and 6.2mA, respectively. The proposed PSFC-QVCO exhibits a better FOM_T of 188.2dBc/Hz and smaller chip area (core area only 0.18 mm²) than previous works.