Selection Criteria for Using DDR, GDDR or MobileDDR Memories in System Designs

摘要

The variety of memory devices available today provides the system architect with multiple options when selecting a memory. The selection is usually driven by key considerations-power, speed, device configurations, cost and pin count. Functionality differences can play a big roll in optimizing system level performance, cost and power. A detailed understanding of the impact of various memory features on the overall system can be critical when selecting the right mix of memory subsystem components. This paper will review popular DDR memory device architectures and provide a selection criteria to pick the right memory device based on system design objectives. This paper will include a short review of the key features of DDR, GDDR and MobileDDR memory architectures, covering power, speed and cost characteristics as well as key functionality differences that can impact overall system architecture. Using real system design experiences each of the main memory architectures will be used to address system design challenges of sustained bandwidth, reliability, access priority, power savings, and interface requirements. By using real world example designs the reader will learn the key elements of the selection criteria that can be used to guide the choice for a specific memory architecture to solve specific system level application requirements.