This paper presents a practical and simple CPW broadside coupled-line balun with multi-layers profile microstrip line and broadside coupling structure to enhance the coupled coefficient and balanced output bandwidth. Designed broadside CPW coupled-line balun design with a symmetric quarter wavelength coupled-line is developed to increase wider bandwidth efficiency and the return loss is better than the traditional planar marchaned coupled-lines balun. The structure of the designed balun is fairly simple, practical and easily fabricated. The measured results show good agreements with those analyses data.