A C-band low-power sub-1volt current-reused multiphase oscillator

A new sub-1V and low power multiphase voltage-controlled oscillator (QVCO) with current-reused structure is proposed. The proposed core oscillator consists of two N-metal oxide semiconductor (NMOS) and P-metal oxide semiconductor (PMOS) transistors and an additional NMOS-only cross-coupled pair that enhances the effective negative transconductance and facilities the start-up condition at sub-1V supply voltages in modern nm CMOS technologies. In the proposed coupling scheme, the gate of cross-coupled transistors is used for coupling in an 'inphase- anti-phase' manner. Parallel capacitors to the drain-source of transistors have been used for further enhancement of effective transconductance and thus lower power consumption; though the increase of parallel capacitors reduces the tuning range, indicating a trade-off in the proposed QVCO. The proposed quadrature oscillator is designed and simulated in a standard 0.18 mu m RF-CMOS technology. The results of the simulation show that the QVCO has a 9% tuning range from 5.35 GHz to 5.88 GHz, and the phase noise is -119.6 dBc/Hz at 1-MHz offset from the 5.7 GHz carrier while consumes only 1.4 mW from a 0.85-V supply voltage; yielding an excellent figure-of-merit (FOM) of -193.3 dBc that is amongst the best FOMs. Several Monte Carlo and PVT analyses verify the robust performance of the QVCO.