With today's demand for devices having more functionality and reduced sizes, the integration of mixed signal modules into a tightly-designed system in which digital signals are combined with RF/analog signals is crucial. Noise isolation is a key to the success of high-performance mixed-signal modules. Electromagnetic bandgap (EBG) structures are promising solutions for power/ground noise isolation in mixed signal systems. This is due to the characteristic that the periodicity of the EBG structures prohibits electromagnetic wave propagation over certain frequency bands called stop bands. Another advantage of the EBG structures is that the EBG structures can be easily implemented into a system requiring a single power supply without additional vias or layers, which can be expensive. In this paper, an EBG synthesizer using genetic algorithms has been introduced to design EBG structures for given design specifications. The synthesized EBG structures have been modeled and simulated with multilayer finite-difference method (M-FDM), and as a real application of EBG integration in mixed signal systems, an EBG structure has been applied to a prototype load board design. The load board has been successfully analyzed, designed, fabricated, and measured. Reduced noise spectra and better performance of an analog-to-digital converter have been resulted from the integration of EBG.