PHASE NOISE SUPPRESSION TECHNIQUES FOR 5-6GHZ OSCILLATOR DESIGN By

by Yang Zhang, M.S. Washington State University December 2007 Chair: Deukhyoun Heo This thesis presents novel designs of low-phase-noise 0.18μm CMOS LC voltage controlled oscillator (VCO) and quadrature VCO (QVCO) for 5-6GHz wireless communications applications. Using a new capacitor tapping technique, the phase noise of CMOS LC oscillators is lowered based on the improvement of loaded-Q improvement and suppression of flicker noise up-conversion. As a proof of concept, a 4.6GHz LC VCO using this technique is implemented and shows measured phase noise of -120dBc/Hz at 1MHz offset while drawing 7mA from a 1.8V supply. Bottom-series coupling is a low-phase-noise coupling method for QVCOs reported by other researchers recently. In this thesis, new analysis of bottom-series coupling is proposed and proves its phase noise advantage. A 5.3GHz LC QVCO using bottom-series coupling and capacitor tapping is implemented. The measured phase noise is -123dBc/Hz at 1MHz offset while drawing 10mA from a 1.8V supply and is -118dBc/Hz at 1MHz offset while drawing 10mA from a 1V supply. Bulk coupling is another coupling method reported for low-phase-noise QVCO design. Combining bulk coupling and capacitor tapping techniques, a 5.6GHz LC QVCO is implemented and shows measured phase noise of -118dBc/Hz at 1MHz offset while drawing