Simulation and measurement of supply and substrate noise in mixed-signal ICs

Digital noise in mixed-signal circuits is characterized using a scalable macromodel for substrate noise coupling. The noise coupling obtained through simulations is verified with measured data from a digital noise generator and noise sensitive analog circuits fabricated. in the 0.35-mum heavily doped CMOS process. The simulations and measurements also demonstrate the effectiveness of including grounded guard rings and separating bulk and supply pins in digital circuits to reduce substrate coupling.