Experimental results and simulation of substrate noise coupling via planar spiral inductor in RF ICs

While previous studies on substrate coupling focused mostly on noise induced through drain-bulk capacitance, substrate coupling from planar spiral inductors at radio frequency via the oxide capacitance have not been reported. This paper presents experimental data and simulation results for inductor-induced noise in the substrate. Noise coupling from conventional and hollow inductors via the substrate to P+ diffusions with and without guard rings were also examined. A compact model of the inductor and substrate that can accurately match the measured inductor-induced noise is then derived. Using the inductor-substrate model, we investigated the effectiveness of various guard rings configurations to reducing substrate noise coupling, the trade-off between noise coupling and self-inductance, and the coupling of noise from the inductor of a tuned RF amplifier.