A NOVEL 10T, 256 CELLS PER BITLINE 1KB STACKED SRAM DESIGN

Abstract

SRAM performance and stability play important role in designing high performance microprocessors where speed is the main criteria. On the other hand wireless sensors and bio-medical equipment have power saving as top priority. Along with these there are applications where memory access is required at fast rate for certain interval of time and it remains idle for rest of the period like laptops. In today's battery operated electronic devices saving power through voltage scaling of integrated circuits is best solution so increase battery life. But soon problems of reliability and failure of memory came. Hence main emphasis of all designers is to reduce power and optimize performance and reliability. Sub-threshold region of operation provides new opportunity so save power but at the cost of reduced speeds. During memory design memory cell forms the core of complete architecture. Optimizing the power in one cell ensures large saving of power as these units may be repeated for 21° to a,2° in just one processor. Peripherals and routing of word lines play important role in deciding the access time of memory. Hence it's important to design highly efficient peripherals. But it should be kept in mind that these peripheral circuits are continuously used, so there power consumed should not go beyond the limits. This thesis is aimed at development of memory-speed optimized cells and decoders, SRAM cell where leakage prevention and robust design under process variation were top priority. Moreover it was found that JOT Stacked cell can perform successfully in voltage range of 400mV to 1.1V making it the choice for application where dynamic voltage scaling DVS is possible. This was made possible at the cost of increased cell area. In nanometer regime this increase in area is a appreciable tradeoff with process tolerance and less power consuming cell design. Complete layout of prototype 11C SRAM design was made was tested with design rule check. Parasitic were extracted through layout versus schematics. Through circuit level techniques it was ensured that as high as 256 bits can be connected at voltage as low as 400mV.Write back circuitry was implemented to ensure proper writability. Simulations were performed at 90nm technology node.