Concept of spectrum-signal transformation

So far, there have been many front-end studies, but most of them fail to present, in a consistent way, how the signals are transformed throughout the front-end itself. In this paper, it is intended to introduce a unique presentation of spectrum and signal transformation within RF front-ends. This approach should help researchers to have better insight into the high-level modeling and characterization of RF front-ends and accordingly lead to new design strategies.