This chapter presents a unified platform for design and verification of mixed-signal systems using SystemC-AMS standard. The platform bases on a bottom-up design and a top-down verification methodologies. In the methodologies, several hierarchical abstraction levels of the system are considered. These abstraction levels are: system, functional, macromodel and circuit levels. We introduce a simple and efficient solution to implement an interface between system level models and their circuit level realizations. Simulation tools such as SystemC-AMS and Spice simulators are combined with a sizing tool named CHAMS, in order to achieve a unified and standard design and verification environment. Moreover, a transient simulation scheme is proposed to simulate nonlinear dynamic behavior of complete mixed-signal systems. The unified platform is used to design and verify a pipeline ADC. The simulation results prove the effectiveness of the proposed structure and methodology.