A Low Phase Noise Fully Monolithic 6 GHz Differential Coupled NMOS LC-VCO

A fullymonolithic 6 GHz low-phase noise VoltageControlled- Oscillator (VCO) is presented in this paper. It consists in two LC-NMOS differential VCOs coupled through a resistive network and is implemented on a 0.25 ae m BiCMOS SiGe process. This proposed integrated VCO can be used also for phased-array applications to steer the beam over the entire spatial range. In this case, the radiation pattern of the phased antenna array is steered in a particular direction by establishing a constant phase progression in the oscillator chain which can be obtained by detuning the free-running frequencies of the two oscillators in the array. At 2.5 V power supply voltage and a power dissipation of 62.5 mW, the coupled VCO array features a measured worst case phase noise of -102.4 dBc/Hz and -125.64 dBc/Hz at 100 kHz and 1 MHz frequency offset respectively from a 6 GHz carrier. The tuning range is about 400 MHz, from 5.85 to 6.25 GHz, for a tuning voltage varying from 0 to 2.5 V.