Low-frequency noise in nonlinear systems

This paper reviews some recent achievements regarding behavior and modeling of low-frequency noise sources that have the potential to improve phase noise simulations significantly. This paper discusses a heuristic interpretation of how time-varying currents affect low-frequency noise sources, review physics-based device simulations, and then present how the sources can be implemented in commercial circuit simulators. Finally, simulations and measurements of GaAs-based heterojunction bipolar transistors (HBTs) are presented.