Modeling of Substrate Noise Impact on a Single-Ended Cascode LNA in a Lightly Doped Substrate (RESEARCH NOTE)

Abstract

Substrate noise generated by digital circuits on mixed-signal ICs can disturb the sensitiveanalog/RF circuits, such as Low Noise Amplifier (LNA), sharing the same substrate. This paperinvestigates the adverse impact of the substrate noise on a high frequency cascode LNA laid out on alightly doped substrate. By studying the major noise coupling mechanisms, a new and efficientmodeling method is proposed to predict, prior to processing, the LNA performance degradation due tothe substrate noise. Our simulations prove that the model can estimate the magnitude of the spurioussignals appearing at the output spectrum of the 5 GHz LNA, within an acceptable error of 13%.