The objective of this paper is to motivate the design of Radio Frequency (RF) analog filters under the LFT framework. Current increase in filter complexity makes traditional design methods outdated. New methods need then to be developed to tackle this issue. The Linear Fractional Transformation (LFT) is a general tool enabling to represent, analyse and synthesize interconnected systems. Coupling with the so-called KYP lemma, and its extensions, it allows to transpose complex analytical optimization problem into a finite dimensional convex problem under Linear Matrix Inequality (LMI) constraints. That is to say a problem which is optimally and efficiently solvable. All through this paper, illustrations are provided on how using the LFT framework for LC filter design. Finally, potential benefits of such an approach are enumerated, which are mainly based on the generic property of the LFT.