PSRAM设计

caroline11

Ahstruct -This paper describes a newly developed 1-Mbit (128KX 8) pseudostatic RAM (PSRAM). A unique feature of the RAM is its inclusion of a virtually static RAM (VSRAM) mode, while being fully compatible with asard PSRAM. The RAM changes into the VSRAM mode when the RFSH pin is grounded, even in active cycles. The RAM can be used either as a fast PSRAM of 36-11s access time or as a convenient VSRAM of 66-ns access time. The typical operation current and dataretention current are 30 mA at 160-ns cycle time and 30 pA, respectively. In order to achieve high-speed operation, low data-retention current, and high reliability, the RAM uses several new design technologies, that is, delay-time tunable design, a new current-mirror timer, hot-camer resistant circuits, and an optimized arbiter. These technologies are applicable to general advanced VLSI’s.