Impact of intermodulation distortion on spectrum preclusion for DSA: A new figure of merit

This paper discusses the importance of understanding the vulnerability of receivers towards intermodulation distortion. Knowledge of the RF front end non-linearity from a spectrum consumption point of view is of crucial importance in efficient spectrum management. A specific case of intermodulation distortion for Low Noise Amplifier (LNA) is studied to quantify the spectrum consumption. We show that the traditional single point IIP3 definition would render insufficient information about the extent of vulnerability to adjacent channel interference. Consequently we propose a new metric as a Figure of Merit with the inclusion of variation of IIP3 with tone spacing to quantify the LNA performance or tolerance to adjacent channel interference. Example measurements of this new FOM are presented along with the discussion on its utility and importance for efficient cognitive spectrum access.