The thesis analyzes the design challenges that arise when developing high-speed ADCs and shows, through an extensive architecture study, that the SAR topology can be used with a sampling rate of 2.5GS/s if asynchronous processing and a multi-bit per cycle approach are adopted. The transistor-level implementation and simulation of a 6-bit SAR ADC are summarized in order to expose the existing trade-offs in terms of power consumption, speed and area.