Characterization of Substrate Noise Impact on RF CMOS Integrated Circuits in Lightly Doped Substrates

Analog and RF circuit performance in single-chip transceivers can severely suffer from coupling of digital switching noise to the silicon substrate. To predict this performance degradation, a deeper understanding of the impact of substrate noise is absolutely necessary. Using measurements, this impact is studied as the cascade of an attenuation through the substrate from the source of substrate noise to the RF circuit and the propagation through the RF circuit to its output. This approach has been validated with measurements on a 0.25 μm and a 0.18 μm CMOS low-noise amplifier (LNA) and reveals insight in the mechanisms of impact of substrate noise on RF circuits. In addition, impact of a real digital circuit is measured on a 0.18 μm differential CMOS LNA.