A 1-V 27mW 10-GHz LC-NOR-Ring QVCO for UWB-OFDM Direct Frequency Synthesizer

This paper proposes an LC-NOR-ring quadrature voltage controlled oscillator (QVCO). Applied to the direct frequency synthesizer used in the frequency-hopped MB-OFDM UWB system, the ring is designed to enhance quadrature phase accuracy. To prevent from the inactive equilibrium state in an even-numbered delay-stage ring, the QVCO comprises four stages of NMOS-NOR gates that stimulate oscillation and equip with low-voltage operation capability. Inductor loads are used in accompany with the varactors to reduce the power consumption. Realized in a 0.18-mum 1P6M CMOS process, the circuit draws 27-mA current from a 1-V supply. The core circuit occupies an area of 1.012 times 0.35mm
²
. The measured oscillation frequency shows that the QVCO has the range of 9.7GHz to 10.6GHz. The phase noise performance is above -90dBc/Hz from 10-kHz offset in the wideband sense