This paper presents a new methodology for layout-aware synthesis of analog systems. The methodology combines block parameter exploration, block placement and global interconnect routing while maintaining an accurate perspective on the layout parasitics. An original system representation (called Layout Constraint Graphs - LCG) as developed for synthesis. The paper discusses how block parameter exploration, placement and global routing are expressed in terms of the LCG graph. AC and transient performances of each explored solution are obtained using SPICE simulations. Experiments show the generality of the synthesis methodology by providing results for several applications including filters and converters.