Characterization and modeling of the substrate noise and its impact on the phase noise of VCO

This paper presents a simple scheme for estimating the digital switching noise at the sensitive RF nodes with the help of a lumped element model for the substrate network. The model parameters have been extracted from the 2-port RF measurements. The efficacy of different isolation schemes such as grounded P+ guard bars and deep N-well has been investigated using phase noise of a VCO as a figure of merit.