This paper describes a comparative study between traditional and sustainable approaches on a high-speed digital electronics design, demonstrating a solution similar to modern embedded systems. The system was produced on traditional flame retardant 4 (FR4) substrate and on biosourced and biodegradable, sustainable printed circuit board (PCB) substrate based on polylactic acid (PLA) and flax fibers, to evaluate the maturity of ecological substrates. The substrate was first characterized from a radio-frequency point of view, using resonant cylindrical cavities and a resonant microstrip line. Then, the circuit design was constrained by the measured relative permittivity and loss tangent, in order to guarantee a good matching of the differential lines and to reach a low signal distortion. Similarly, the physicochemical properties of the substrate induced the choice of processes for etching and soldering the components. The matched transmission lines were simulated with ADS software using input/output buffer information (IBIS) models of the digital circuits. Their characterization was conducted with eye diagram and time domain reflectometry technics. As an introduction, a life-cycle analysis (LCA) was conducted to evaluate the ecological impact part of the FR4 PCB among this electronic board life cycle impact.