The terahertz frequency band offers a wide range of sensing and imaging applications. In the recent years, silicon technologies have been increasingly used for detecting and generating terahertz signals. This trend has been a major success to further reduce the size and cost of terahertz systems. Despite physical limitation related to the devices speed and cutoff frequencies, circuit design techniques have been implemented to integrate terahertz systems well beyond those limitations. One of the major goal is to further extend the application field by implementing extremely wide-band terahertz systems. This presentation will focus on the synthesis, detection and interpretation of multispectral signal at mm-wave and terahertz frequencies for imaging applications.