18-Saad Qureshi SRAM - SRAM SRAM SAAD QURESHI ECE 3080...

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Unformatted text preview: SRAM SRAM SAAD QURESHI ECE 3080 Overview Overview History of RAM History Structure And Operation of SRAM Structure Application Application Future of SRAM Future Birth of Memory Birth Mid-1960s-discussion of development of randomMid access memory (RAM) using MOS technology at IEEE Solid-State Circuits Conference. 1974- first commercial 1024-bit (1 Kb) MOS RAM 1974 developed. Modern day- storage capacity increased to more than 1 Modern million times the storage capacity of the original RAMs. SRAM Static Random-Access Memory SRAM (SRAM) Static Memory-holds data as long as power is applied Static SRAM- able to store information in bit format SRAM Main storage unit consists of two cross- coupled Main inverters Structure Structure Standard 6T-Cell Structure Standard Transistor MA1 and MA2 provide path to access data Complete schematic showing all six CMOS or NMOS transistors Operation Operation 1. 2. 3. Three modes of operation: Three Standby or Idle Read Write Standby Standby Wordline not asserted or kept low Wordline Data access transistors- MA1 and MA2 disconnect Data cell from bit lines Inverters continue to store information. Inverters Read Read 1. 2. 3. 4. 5. Pre-charge both bitlines (BL) high using sense amplifier Turn on Wordline MA1 and MA2 turn on and allow access to inverters Current flows as shown into the Bitlines and causes the sense amplifier to assume same state as data stored on cell The Bitlines voltages also settle at the same values as D1 and D2 Read Continued Read Figure (right) shows final Figure steady state of 6T-cell No current flow through MA1 No or MA2 Memory waveform during Memory read operation State of memory cell disturbed State but not destroyed Write Write Bitlines are initialized Bitlines with the data to be written Wordline is turned Wordline on-access to cell created Bitlines overpower cell with new value Effect of Voltage Effect The graph shows that access time or read/write time The varies inversely with input voltage Decreasing the input voltage increases the access time Decreasing Effect of Temperature Effect Data access times are improved when the temperature Data is decreased The graph below shows this relationship between The access time and temperature Applications Applications SRAM is used in personal computers, workstations, SRAM routers and peripheral equipment In Computers it is used for internal CPU cashes In LCD screens and printers also normally employ static LCD RAM to hold the image displayed Small SRAM buffers are also found in CDROM and Small CDRW drives SRAM benefits over other RAMs SRAM SRAM is more power efficient than the highly used SRAM DRAM (Dynamic Random-Access Memory) Faster data access as compared to DRAM Faster Easier to control than DRAM Easier Future uses Future SRAM variant 1T-SRAM developed by MoSys, Inc SRAM combines the benefits of both SRAM and DRAM-high speed of access while reducing overall size. 1T-SRAM used in the Nintendo Wii to allow faster 1T load times Intel's new 32nm chip for its new processor line due to Intel's to begin production in 2009 will utilize SRAM Questions? Questions? Sources Sources Jaeger, Richard. Microelectronic Circuit Design. Third edition Jaeger, Microelectronic Third Prince, Betty. High Performance Memories. 1999 Prince, High http://en.wikipedia.org/wiki/Static_random_access_memory http://en.wikipedia.org/wiki/Static_random_access_memory http://en.wikipedia.org/wiki/Computer_memory http://en.wikipedia.org/wiki/Computer_memory http://en.wikipedia.org/wiki/1T-SRAM http://en.wikipedia.org/wiki/1T http://www.mosys.com/Products/1T-SRAM/Single-port-1Thttp://www.mosys.com/Products/1T SRAM.aspx http://whatis.techtarget.com/definition/0,,sid9_gci523855,00.ht http://whatis.techtarget.com/definition/0,,sid9_gci523855,00.ht ml ...
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This note was uploaded on 08/23/2011 for the course ECE 3080 taught by Professor Staff during the Spring '08 term at Georgia Institute of Technology.

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