A high performance SDRAM controller for HDTV decoder is designed.MB-based (macro block)address mapping,adaptive-precharge and command interleaving are adopted in this controller.MB-based address mapping reduces the precharge operations of the video processing unit in one access;adaptiveprecharge avoids unnecessary precharge operations;while command interleaving inserts the precharge and activate commands of the next access into the command sequence of the current access,thus reduces the no operation(NOP)cycles.Combination of these three schemes effectively improves the SDRAM performance.Compared with precharge-all scheme,adaptive-precharge and command interleaving reduce the SDRAM overhead cycles by 70% and increases SDRAM performance by up to 19.2%in the best case.This controller has been implemented in an AVS SoC and the frequency is 200MHz.