Amplitude and phase noise in modern CMOS circuits

The classical long-channel MOSFET noise formulation underestimates the drain current noise of short-channel devices by a factor often referred to as the excess noise factor. In order to predict the effects of this excess noise on amplitude and phase noise in future circuits, it is crucial to have a reliable MOSFET noise model and an accurate phase noise formulation.; In this dissertation we first present the semi-ballistic MOSFET noise model based on the transport properties of ballistic MOSFETs. Unlike most existing models, this model is not based on the long-channel formulation. Thus it does not require continual revision as we discover emerging short-channel effects. By studying noise in ballistic MOSFETs and using results of historic studies on vacuum tubes, we show that noise in short-channel MOSFETs is partially-suppressed shot noise. Using this model, we study the overall noise performance of future MOSFETs and discuss its implications for the future of analog circuit design.; We then discuss the effects of device noise on the phase noise of electrical oscillators and introduce the time-domain formulation of phase noise which is especially accurate for switching-based oscillators. This method can be used to predict phase noise for a given device noise level or to calculate the device noise from phase noise data. The latter application is called indirect device noise characterization through phase noise measurements, a method that we introduce in this work. The time-domain phase noise formulation can also be used to investigate properties of phase noise, especially at close-in frequencies. We explore all of these applications.; We validate our MOSFET noise model using hydrodynamic device simulations. The accuracy of our phase noise formulation is then verified by presenting experimental data on the phase noise of ring oscillators with various device sizes. Finally, we present an unsymmetrical ring oscillator, especially-designed for MOSFET noise characterization. We show that indirect noise characterization facilitates the extraction of device noise parameters and these parameters substantiate the validity of our MOSFET noise model. Our findings provide insight about the future of analog CMOS design and guidelines for low-noise circuit design and device engineering.