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MIT 6.004 Computation Structures, Spring 2017Instructor: Chris TermanView the complete course: https://ocw.mit.edu/6-004S17YouTube Playlist: ... ... <看更多>
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MIT 6.004 Computation Structures, Spring 2017Instructor: Chris TermanView the complete course: https://ocw.mit.edu/6-004S17YouTube Playlist: ... ... <看更多>
#1. DRAM 原理1 :DRAM Storage Cell - 蜗窝科技
Differential Sense Amplifier 包含Sensing Circuit 和Voltage Equalization Circuit 两个主要部分。它主要的功能就是将Storage Capacitor 存储的信息 ...
#2. 第二十一章記憶體電路
(1)隨機存取記憶體(RAM):可細分為靜態SRAM 與動態DRAM。 (2)唯讀記憶體(ROM):可再分 ... 稱為感測放大器(sense amplifier)。 ... (一) 結構特色與所用原理.
#3. DRAM 原理1 :DRAM Storage Cell - 程式人生
Differential Sense Amplifier 包含Sensing Circuit 和Voltage Equalization Circuit 兩個主要部分。它主要的功能就是將Storage Capacitor 儲存的資訊 ...
#4. 2.1.2. 動態RAM · 每位程式設計師都該知道的記憶體知識
圖2.5 示意了常見的DRAM 記憶單元設計結構。 ... 資料線路必須被連接到感測放大器(sense amplifier),其能夠根據仍需計作1 的電量範圍來分辨儲存的0 或1。
#5. DRAM的工作原理 - 知乎专栏
DRAM (Dynamic Random Access Memory, 动态随机访问内存),是现在主流的内存形式。基本单元主要由一个晶体管和一个电容组成,电容中有电荷代表“1”,没有电荷代表“0”。
Differential Sense Amplifier 包含Sensing Circuit 和Voltage Equalization Circuit 两个主要部分。它主要的功能就是将Storage Capacitor 存储的信息 ...
在現代DRAM中Open Bitlines結構幾乎不用了,但隨著工藝的發展,理論上Open Bitlines的優點更大。 1.2.2 差分感應放大器. A. 作用. 1)將bitline上的微小 ...
#8. DRAM 原理2 :DRAM Memory Organization - 壹讀
DRAM 在設計上,將所有的Cells 以特定的方式組成一個Memory Array。 ... 從圖中我們可以看到,增加Bitline 後,Sense Amplifier、Read Latch 和Write ...
#9. 鎖存型讀出放大器(Sense Amplifier)電路探討 - 古詩詞庫
因儲存器陣列的相似結構,讀出放大器不僅在SRAM中使用,在其他種類的儲存器如動態隨機儲存器(DRAM),快閃記憶體(Flash Memory)中也得到廣泛使用。從 ...
#10. CN102881331A - 灵敏放大器的控制电路及包括其的dram
Similar Documents ; KR101676724B1 2016-11-16 향상된속도를갖는기록-보조된메모리 ; US7158430B2 2007-01-02 Bit line sense amplifier control circuit ; CN102394094B ...
#11. Sense amplifier with offset mismatch calibration for sub 1-V ...
In this paper, a sense amplifier circuit, which aims to operate with 1V or less ... The relaxed amount can be utilized for lowering Vcore, the DRAM core ...
#12. 锁存型读出放大器(Sense Amplifier)电路探讨 - 机器之心
我们有幸请到了UCLA的PhD KO大神来为我们介绍一些sense amplifier ... 的存储器如动态随机存储器(DRAM),闪存(Flash Memory)中也得到广泛使用。
#13. (a) Conventional DRAM sense amplifier circuit and (b) its ...
Download scientific diagram | (a) Conventional DRAM sense amplifier circuit and (b) its sensing waveforms (NMOS side operation only). from publication: A ...
#14. 作為一個程式設計師,你不得不知道內存(DRAM)的工作原理
每一條行地址線路會與多條列地址線路和cell相連接,為了偵測列地址線路上微弱的激活信號,還需要一個額外的感應放大器(Sense Amplifier)放大這個 ...
#15. Flash Memory中灵敏放大器的设计
circuits--sense amplifier. ... Key words: Flash Memory; full-CMOS; sense amplifier; simulation ... 动态随机存取存储器(DRAM)存储单元的存储结构及工作原理:.
#16. 圖解RAM結構與原理,系統記憶體的Channel、Chip與Bank
而RAM 在電腦裡又可大致上分為2 種:SRAM 和DRAM,兩者的基礎原理 ... 組bank 的下方還會有個row buffer(sense amplifier),負責將獨出的row 資料暫 ...
#17. RAM (Random Access Memory)
capacitor DRAM cell, http://www.cmoset.com/uploads/4.1-08.pdf ... Basic organization of DRAM internals ... to overwrite sense amplifiers and DRAM cells.
#18. Multiple subarray DRAM having a single shared sense amplifier
The first stage of sense amplifiers/latches located at each DRAM array is used for ... for sensing, also is the write circuit for writing to the DRAM cells ...
#19. 於動態隨機存取記憶體技術對N型金氧半場效電晶體與N型感測 ...
... 使得電路切換的速度以及電子元件的耗電量都必須跟著降低,特別是對於暫態隨機存取記憶體(DRAM)的操作過程,若在周邊電路(periphery circuit)中感測放大器的電流不夠 ...
#20. DRAM基本工作原理 - 百度文库
DRAM 基本工作原理-而資的傳輸徑則是藉由字元線、位元線、資輸出入線(I/O線)等徑進 ... 儲存在記憶單元中的訊號,因此m 條位元線具有m 個感應放大器(sense amplifier)。
#21. (23-25 DRAM Circuits) - UMD ECE Class Sites
Part II, DRAM Circuits. Prof. Bruce Jacob [email protected] ... material taken from Keeth & Baker's DRAM Circuit Design. ... Sense Amplifiers II. Basic idea:.
#22. Latched CMOS DRAM Sense Amplifier ... - Semantic Scholar
Aiming for a systematic evaluation of DRAM sense amplifier performance, the SA is modeled using small signal equivalent circuit approach in order to analyze ...
#23. Robust Design of DRAM Core Circuits - Yield Estimation and ...
Chapter 5 describes the leakage effects in DRAM cells. Some mathematic ... 2.1 DRAM Cell and Pre-sensing . ... 3 DRAM Sense Amplifier and Sensing Techniques.
#24. Offset-Compensation High-Performance Sense Amplifier for ...
The transistor offset from sense amplifiers affects the sensing performance in dynamic random-access memory (DRAM).
#25. 【DRAM】DRAM基本结构与原理 - 360Doc
所以当transistor选同时,存储在存储电容上的电荷传输到Bitline时,Bitline上的电压变化很小,需要使用差分比较放大器(此差分比较放大器非模拟集成电路中 ...
#26. 積體電路雜訊偵測關鍵技術研究(II) 研究成果報告(精簡版)
一般的PDSH 電路的工作原理與時序 ... 圖一峰值偵測電路時序與工作原理. 圖二峰值偵測電路 ... (英文)A 0.5V high speed DRAM charge transfer sense amplifier.
#27. Sense amplifier - Wikipedia
Sense Amplifiers are primarily applied in Volatile memory cells. The memory cells are either SRAM or DRAM cells which are laid out in rows and columns on ...
#28. 簡介]DRAM系統- 看板VideoCard - 批踢踢實業坊
Sense Amplifier 會偵測電壓變化來判定bit的1/0,並順便回寫資料. ... edge trigger的方式不同,但是原理相同) 原先DRAM中,Row,Col必須都送.
#29. Design of DRAM with Coupled Sense Amplifier for Low Power ...
A DRAM circuit consists of row decoder, column decoder, input and output buffers, sense amplifier and memory array. This paper is organized as follows. Section ...
#30. Latched CMOS DRAM Sense Amplifier Yield ... - Springer Link
Aiming for a systematic evaluation of DRAM sense amplifier (SA) performance, the SA is modeled using small signal equivalent circuit approach in order to ...
#31. Design of dynamic genetic memory - PMC - NCBI
A typical DRAM memory cell consists of a capacitor C s and a transistor M1; ... For the reading cycle, a sense amplifier is used to detect the unrecognised ...
#32. Switched capacitor DRAM sense amplifier with immunity to ...
Voltages developed across the first and second input capacitors compensate for offset voltages developed in the sense amplifier circuit due to the mismatches in ...
#33. 14.2.3 DRAM - YouTube
MIT 6.004 Computation Structures, Spring 2017Instructor: Chris TermanView the complete course: https://ocw.mit.edu/6-004S17YouTube Playlist: ...
#34. A DRAM Sense Amplifier Circuit by Multi-pillar Vertical ... - Confit
[J-5-4] A DRAM Sense Amplifier Circuit by Multi-pillar Vertical MOSFET Realizing Sub-1V Core Voltage Operation without Overdrive Technique.
#35. 7 DRAM TECHNOLOGY - Smithsonian Chip Collection
DRAM Technology. INTEGRATED CIRCUIT ENGINEERING CORPORATION. 7-2. Data. Data. Sense. Amplifier. Data. Data. Sense. Amplifier. Data. Data. Sense. Amplifier.
#36. Memory Basics
Dynamic: must be refreshed periodically (DRAM) ... bit and bit_bar read by a sense amplifier. • Sense Amplifier. – basically a simple differential amplifier.
#37. DRAM architecture with combined sense amplifier pitch - Google
The present invention provides an integrated circuit memory that minimizes chip area and further avoids the use of complex voltage boosting circuits. The memory ...
#38. Signal Margin Analysis for DRAM Sense Amplifiers
Spatial analysis gives further insight into the sensing limitations. This can be used to improve the circuit modeling of the sense amplifier and to simulate ...
#39. ECE 224a Lecture 1
STMicro/Intel/UCSD/THNU. DRAM. Bitline cap is an order of magnitude larger than the cell, causing very small voltage swing. A sense amplifier is used.
#40. Investigation of different CMOS DRAM sense amplifier ...
Principle of Operation. 17. 2. Simulation Results for The. Standard Current Mirror Circuit. 19. B. The Modified Configurations. 20. 1 ...
#41. 美光科技公司-產品工程師-面試經驗分享 - 1111人力銀行
畫出Sense Amplifier Schematic 說明如何應用於DRAM中,並解釋其原理並考到,Sense Amplifier把訊號拉到0或VDD,哪個比較慢?
#42. DRAM的架构/标准/特点/未来展望(dram结构和原理) - 睿象云
这些电流将微幅改变每条位元线的电压,这个小改变会由感测放大器(sense amplifier)侦测出来。 感测放大器这种结构会将小幅增加的电压放大成高电压(代表逻辑1),并把微 ...
#43. An asymmetrically controlled sense amplifier with boosted ...
The bit-line sense amplifier (BLSA) is the crucial circuit for correct DRAM data sensing. The ability of BLSA to sense the data to proper ...
#44. 深入浅出DDR系列(二)--DDR工作原理【转】 - srekyba - 博客园
然后DRAM 再将Active Command 所选中的Row 中,DRAM 就将Memory Array 中的数据从DRAM Cells 中读出到Sense Amplifiers,或者将数据从Sense Amplifiers 写 ...
#45. Sense amplifier | McGraw Hill's AccessScience
An electronic amplifier circuit used to sense and refresh the value of a bit stored in a memory cell of a dynamic random access memory (DRAM) integrated ...
#46. Circuit Design of DRAM for Mobile Generation - KoreaScience
reduced driving strength of the BL sense amplifier. Direct current sensing scheme improves the sensing performance by using an NMOS differential pair to.
#47. Physical Design of DRAM Cell: - Inderjit Singh
Cross-coupled nMOS sense amplifier circuit : Assume that both columns (bit lines) are being pulled up during the precharge cycle and that the voltage on the bit ...
#48. Storage - RAM - LostJeffle - Bitcron
... Memory),主要包括SRAM (Static RAM) 与DRAM (Dynamic RAM) 两类 ... 入的电平状态;之后BL 与$\overline{BL}$ 之间的sense amplifier 通过感知BL ...
#49. 6-2-1 SRAM之工作原理
DRAM 使用時需要設計刷新電路,導致使用不便及速度慢. 有些廠商將刷新電路做在DRAM 內部,以計數器控制自動刷新動作. 可簡化外部電路設計,讓使用的便利性有如SRAM ...
#50. Inverted bit‐line sense amplifier with offset‐cancellation ...
An inverted bit-line sense amplifier (BLSA) equipped with offset compensation capability for low-power DRAM applications is proposed.
#51. Impact of Processing Technology on DRAM Sense Amplifier ...
John Nickel served as my mentor during my first assignment, patiently teaching me CMOS circuit design. Jim Yankosky, John. Barth, and John ...
#52. 嵌入式DRAM 測試方法研究成果報告(精簡版)
to the commodity-DRAM testing and SRAM testing since an eDRAM core utilizes the DRAM cells with the ... The control circuit (CTL) and global sense amplifier.
#53. D14-039 - 旺宏教育基金會
及操作原理有很多種,簡單來說,在ReRAM的兩端點施加電壓,. 可以改變ReRAM的阻值,達到存0存1的 ... 是swing-sample-and-couple voltage mode sense amplifier (SSC-.
#54. MODIFIED DRAM CELL DESIGN USING HIGH-K MOS ...
We have implemented the capacitor model developed in Verilog-A code in a DRAM circuit consisting of two memory cells and a sense amplifier. The circuit is taken ...
#55. DRAM 原理2 :DRAM Memory Organization - 台部落
在 DRAM Storage Cell 章節中,介紹了單個Cell 的結構。 ... 從圖中我們可以看到,增加Bitline 後,Sense Amplifier、Read Latch 和Write Driver 的 ...
#56. A Sense Amplifier Scheme with Offset Cancellation for Giga ...
As operating voltages decrease, the sense amp circuit becomes slower, because of the lower NMOS gate-to- source voltage. In DRAM a lot of the power consumption ...
#57. SRAM的工作原理是什么? - 品慧电子网
SRAM的速度快但昂贵,一般用小容量的SRAM作为更高速CPU和较低速DRAM 之间的 ... 灵敏放大器(Sense Amplifier),控制电路(control circuit),缓冲/驱动电路(FFIO)。
#58. SRAM and DRAM Peripherals - Electrical Engineering (EE)
This difference in these voltages is detected by the sense amplifier to produce and output voltage, which corresponds to te stored value in the cell which is ...
#59. A Write-Back-Free 2T1D Embedded DRAM with Local Voltage ...
We also proposed various circuit techniques for mitigating read disturbance issues including a local-sense- amplifier scheme. In addition, a dual-row-access low ...
#60. Performance evaluation of 64 bit SRAM and DRAM - ProQuest
Overview of RAM. In Figure 12, RAM consists of the following circuits: memory array, sense amplifier, pre-charge and equalizing circuit, row and column decoder, ...
#61. DRAM Reliability - TU Delft Repositories
DRAM reliability prediction model that can be used in the circuit design phase. ... sense amplifier it holds that higher radiation doses break down the ...
#62. Effective Activating Compensation Logic for Drams in 3D-ICs
failure of DRAM caused by BTI effect in 3D stacked system which degrades circuit functionality ... in DRAM, duty cycle of sense amplifier is closely related.
#63. CN102682827A DRAM的读出放大器的控制电路及包括其的 ...
Control circuit of read amplifier of dynamic random access memory (DRAM) and ... 在该模块中,读出放大器为常规的SA(Sense Amplifier,灵敏放大器),该使能控制 ...
#64. Design-Induced Latency Variation in Modern DRAM Chips
⑥ Data from the global sense amplifiers is then sent to the memory channel through the IO interfaces of the DRAM chip. Both DRAM row and column accesses are ...
#65. News Releases from Headquarters : Sep 26, 2001 - Hitachi
High-speed DRAM circuit technology for the 1V generation ... the sense amplifier circuit, resulting in an overall decrease in DRAM operation ...
#66. A 16-Mbit DRAM with a relaxed sense-amplifier-pitch open-bit ...
For reducing in-ter-bit-line coupling noise, the DRAM features a latched-sense, shared-sense circuit with open bit-line readout and folded bit-line rewrite ...
#67. Improving the Performance and Efficiency of Bulk Bitwise ...
We implement the DRAM sense amplifier circuit us- ing 55nm DDR3 model parameters [57], and PTM low-power transistor models [56, 76]. We use cell ...
#68. 作为一个程序员,你不得不知道内存(DRAM)的工作原理 - 简书
每一条行地址线路会与多条列地址线路和cell相连接,为了侦测列地址线路上微弱的激活信号,还需要一个额外的感应放大器(Sense Amplifier)放大这个 ...
#69. 深入浅出DDR系列(2)——带你继续扒DDR工作原理-
然后DRAM 再将Active Command 所选中的Row 中,DRAM 就将Memory Array 中的数据从DRAM Cells 中读出到Sense Amplifiers,或者将数据从Sense ...
#70. 计算机组成原理第四章存储器
-SRAM/DRAM原理、主存系统构建. 唐本第四章$4.1,$4.2. COD5 $5.2,A.9 ... 由于存取原理的不同,又分为静态RAM和动态 ... Sense & Refresh amplifier ...
#71. DRAM sense amplifier active matching fill features for gap ...
Latest Micron Technology, Inc. Patents: · 34 may include a number of circuits, such as a clock input circuit · 40 and a command address input ...
#72. High-speed charge transfer sense amplifier for 0.5 V DRAM ...
Besides, both high voltage pre-charge levels and high voltage control signals are not required in this proposed circuit as compared with prior arts. Keywords:.
#73. Dynamic Random Access memory project - Studocu
FInal project report dram circuit design purpose of this paper is to present the learning ... sense amplifier Precharge equalizers and address decoders.
#74. Low power and improved speed 1T DRAM using dynamic logic
efficient implementation of a sense amplifier. ... logic DRAM circuit has compared with the designed circuit and other existing circuits.
#75. A 0.94 W 611 KHz In-Situ Logic Operation in Embedded ...
Embedded DRAM Memory Arrays in 90 nm CMOS. Myeong-Eun Hwang 1 ... arrays of sense amplifiers and row and column address decoders.
#76. Lecture 27 Semiconductor Memory: DRAM and Non-Volatile ...
1T DRAM requires a sense amplifier for each bit line, due to charge redistribution read-out. DRAM memory cells are single ended in contrast to SRAM cells.
#77. 單端式DRAM陣列的存取結構 - 電子工程專輯
嵌入式DRAM(eDRAM)經由單端式感應裝置(single-ended sense device)獲得單端式儲存單元(storage cell)的儲存狀態。eDRAM相對於應用差動感應放大器 ...
#78. Renesas Electronics Introduces 576-Megabit Low-Latency ...
Renesas Electronics Introduces 576-Megabit Low-Latency DRAM for Network ... existing low-latency DRAM by leveraging the company's high-speed sense amplifier ...
#79. A Novel High-Speed Sense Amplifier for Bi-NOR Flash ...
for DRAM or SRAM, but few have been discussed about the mismatch of sense amplifiers. Another category of memories is flash memory [4], [5].
#80. DESIGN AND IMPLEMENTATION OF 8X8 DRAM MEMORY ...
DRAM memory array are as follows. 1. DRAM cell. 2. Pre-charge circuit. 3. Read and write control circuit. 4. Sense amplifier. 5. Row and column decoder.
#81. Understanding Latency Variation in Modern DRAM Chips
One major DRAM vendor presents a circuit design for a contemporary sense amplifier, and observes that it senses the VDD value on the bitline ...
#82. [특허]Sense amplifier circuit and method for a dram
A sense amplifier of a DRAM includes, in series between two terminals of application of a supply voltage, at least one first transistor of a first channel ...
#83. DESIGNING OF VARIATIONS TOLERANT SENSING ...
Sense amplifier circuits are used to sense the voltage levels on the bitlines [1]. The reliable operation of the circuit requires perfectly matched transistors ...
#84. A Circuit-Level 3D DRAM Area, Timing, and Energy Model
In this chapter, we first present component modeling such as transistor, driver, repeater, address decoder, and sense amplifier model. Along with the components ...
#85. DRAM Design Overview Contents - Stanford University
/pre#. # is bank No. MWDEC level shifter. VPP. Feb. 11th. 1998. DRAM Design Overview. Junji Ogawa. Sense Amplifier Circuits - Folded Shared Interleaved -.
#86. Dynamic Random Access Memories; Dynamic RAMs, DRAMs
The enabled transistor allows the voltage on the capacitor to be read by a sensitive amplifier circuit through the 'bit' line. This sense circuit is able to ...
#87. HIGH SPEED LOW POWER EMBEDDED DRAM DESIGN ...
Sense amplifier is a circuit that is able to recognize if a charge has been loaded into the capacitor of the memory cell, and to translate this charge or lack ...
#88. IMPLEMENTATION OF DRAM USING SELF VOLTAGE LEVEL ...
current in the circuit implementing of DRAM using self-controllable voltage ... BL so the output is sending to sense amplifier we will get as output =1.
#89. Novel Low Power Cross-Coupled FET-Based Sense Amplifier ...
In this study, LTSpice software is used to come up with a high-performance sense amplifier circuit for low-power SRAM applications. Throughout this research ...
#90. DDR4 DRAM 101 - Circuit Cellar
ACT signals control the data movement and control of the sense amplifiers. FIGURE 4 – 1 bit storing (left) and sense amplifier (right). FIXED ...
#91. 記憶體設計探索 - COMPOTECH Asia
圖1是傳統的6T SRAM cell的電路圖,不論是DRAM還是SRAM,每個記憶細胞都 ... 位元線的電阻會產生壓降,必須使用感測放大器(Sense Amplifier)將微弱的 ...
#92. IMPLEMENTATION OF MODERN DRAM USING CMOS ...
The work includes designing of write driver circuit, pre-charge circuit, memory cell, Sense amplifier and row decoder. The. DRAM Memory array ( ...
#93. [DRAM] Differential Sense Amplifier(차동 증폭기)
sense amp의 핵심은 sensing circuit(감지회로)라고 되어 있는 4개의 서로 연결되어있는 트랜지스터들 입니다. 감지회로는 SAN(Sense-Amplifer N-Fet ...
#94. 메모리 시스템 Ch8_'DRAM 디바이스 조직 : 기본 회로와 구조-3'
8.4.1 DRAM 디바이스 상에서 sense amplifier의 기능 ... 회로의 핵심은 감지회로(sensing circuit)라고 되어있는 4개의 서로 연결되어있는 ...
#95. sense amplifier 的功能以及实现过程 - BiliBili
内存pin脚介绍,以及为什么要引入 sense amplifier. 160 · 24:54 ; memory sense amplifier introduction. 82 · 19:24 ; 信号为啥会失真. 132 · 29:20 ; memory ...
#96. Memory Systems: Cache, DRAM, Disk - 第 362 頁 - Google 圖書結果
Figure 8.10 shows the circuit diagram of a basic sense amplifier. More complex sense amplifiers in modern DRAM devices contain the basic elements shown in ...
#97. Integrated Circuit and System Design. Power and Timing ...
Latched CMOS DRAM Sense Amplifier Yield Analysis and Optimization Yan Li1, Helmut Schneider2, Florian Schnabel2, Roland Thewes2, ...
dram sense amplifier原理 在 簡介]DRAM系統- 看板VideoCard - 批踢踢實業坊 的推薦與評價
1. 1bit DRAM
1bit DRAM由一個電晶體以及一個電容器組成.
Bitline
|
|
+---| |--- VCC
| | |
| [---]
--+--
|
RowLine
利用電晶體控制線路是否與電容相接.
接著以電容內的電位高低(有無電荷)
決定這個bit內容是1還是0.
但是這樣結果就是.電容內的資料只要一讀取
就會消失.所以必須讀取後將資料回寫.同樣的電容
一段時間沒理他電荷還是會跑掉.因此必須一段時間內
(按:不超過幾十ns等級的時間)就refresh一次.
當然DRAM(1T,T=transistor)因此可以比起SRAM的4T/6T
擁有較低成本以及高容量單位密度的優勢.因此DRAM佔據了
主流的記憶體系統很長的一段時間,而修正DRAM的效率的各種
實作也是曾出不窮.也幾乎都曾經採用於顯示系統上.
===============================================
詳細原理請翻查數位系統或是電子電路相關教科書.
這裡重點是.DRAM的效率問題來自於電容導致在讀取
後需要寫回以及必須定期refresh.限制了效率表現.
===============================================
2. DRAM array
實際上的DRAM晶片是以2D array的方式組成的.
Col 0 -----------------------------------------
| | | |
VCC ...........................................
| | | |
Col 1 ------------------------------------------
| | | |
VCC ...........................................
| | | |
Col 2 ------------------------------------------
| | | |
VCC ...........................................
| | | |
Col 3 ------------------------------------------
| | | |
VCC ...........................................
| | | |
Row0 Row1 Row2 Row3
(每個Row,Col相連的地方都有如上圖的1bit DRAM存在.
但是我畫不進去...放棄)
每1bit的資料都可以Row/Col的位址決定.當在外部
決定好Row/Col的位址後.也就可以從DRAM array中
讀寫這1bit的資料.
一個典型的RAM晶片規格標示,如16Mx8,表示這顆的傳輸
資料寬度為8bit,而ADDRESS總共有8Mega"組"8bit資料.
因此總容量是128Mbit.
這樣一顆晶片就可以看成有如上的DRAM array 8組.
而每組的Row/Col數量?通常兩者數量會僅可能的接近.
那麼就是有4096 Row以及4096 Column.
3. A DRAM Chip
那麼要如何把以上16Mx8的設計出一個對應晶片的介面呢?
Column以及Row的address各需要12bit.不過我們可以讓它
使用同一組訊號線分兩次傳遞(這稱作row/column multiplexing,
而DRAM基本上都是採用此種方式.也因此影響了效能).因此只要
一組12bit的位址線就夠了.但是需要額外的訊號線通知晶片
正在送的是Row還是Column,因此可以增加兩條1bit的訊號線.
RAS#(Row Access Signal)以及CAS#.當然還要訊號線告知
現在是讀取或是寫入.以及當晶片準備好傳送資料時通知完成的
訊號線.以及8bit的資料線.
[-------]
Address=| |=Data Output(1:8)
(0:11) | |
| |
WE#-| |
RAS# -| |-OE#
CAS# -| |
[-------]
內部應該是長的這樣:
Address(0:11)
==================|
|| [Column Decoder]
|| ------------------
|| Row | |
=== | DRAM Array |
Dec | |
ode | |
r | |
--------------------
| | | | | | | |
v v v v v v v v
----------------
DRAM Sense --->Output Buffer==>Data Output
Amplifier --->
Address送入後.依照RAS#,CAS#判斷現在是Row還是Col的定址.
然後把位址送到ROW or Col的decoder,由decoder啟動對應的
row/col的線路.Row/Col的位址都決定後.Sense Amplifier
會偵測電壓變化來判定bit的1/0,並順便回寫資料.
最後讀取到的資料送到output buffer.因為這顆是16Mx8的晶片.
所以晶片內部應該會有8組同上的Array/Decoder/Sense Amp.
Output buffer將它組成8bit輸出.
DRAM Read Timing
RAS# ----|__________________|--
CAS# --------|______________|--
ADR ====XOOOXOOOX============
11:0 Row Col
WE# _|-----------------------|_
OE# ----|____________________|-
DQ ===============XOOOOOOX===
8:1 Valid Data
DRAM Write Timing
RAS# ----|__________________|--
CAS# --------|______________|--
ADR ====XOOOXOOOX============
11:0 Row Col
WE# --------------|_______|---
OE# _|----------------------|_
DQ ===============XOOOOOOX===
8:1 Write Data
嗯,好極了.終於可以開始傳資料,我們只要"每次"
都送Row,Col位址進去,就可以讀或者寫入8bit的資料.
等等.這是否有哪裡不對勁......??
每次都要送Row/Col,那麼是不是花在送Row/Col的時間
比等待資料傳輸的時間還要多??沒錯.....
所以這顯然不是個好現象.有沒有辦法改進呢?
==================================
Row/Column multiplexing也限制了DRAM的性能
==================================
DRAM的加速: Paged Mode/Fast Paged Mode
既然送Row,Col要花很多時間,可不可以偷懶不送..??
但是不送的話,又要怎麼知道要存取哪邊呢?折衷一下.
只送一個.而另外一個不送的話就假設跟以前一樣.
這是DRAM系統第一個普遍的加速手段.稱為Paged Mode
或者是Fast Paged Mode(事實上這兩者有少許差異,
edge trigger的方式不同,但是原理相同)
原先DRAM中,Row,Col必須都送.
Addr <Row><Col>------<Row><Col>------<Row><Col}
Data <Data> <Data> <Data>
Paged Mode/Fast Paged Mode
Addr <Row><Col> <Col> <Col> <Row><Col>
Data <Data> <data> <data> <data>
可以大幅度增加DRAM的效率.
DRAM的加速: EDO RAM(Hyper Paged Mode DRAM)
EDO RAM是在SDRAM之前普遍的一種加速DRAM.它進一步
擴展了fast paged mode,主要的改進為送下一個Column Address
的時候可以不用等待前一個Data輸出完成.而重疊兩者的時間.
EDO RAM(Hyper Paged Mode)
Addr <Row><Col 0><Col A><Col B> <Row><Col>
Data <Data0><dataA><dataB> <data>
另外我還找到一個說法表示.EDO RAM會預設下個Col為這個Col
的次一個而預先準備,進一步縮短access time.不過我不確定
是否所有的EDO RAM都支援.或者是僅有部分access time
較低的EDO RAM是如此.還是這是burst EDO才加入的.
Burst EDO:快速消失
Burst EDO支援burst Mode.基本原理為...在DRAM
內部將array再分割成更小可獨立運作的internal bank.
然後同步存取這些internal bank,讓它們在同一段latency
後差不多都準備好了.而可以在接下來最短的時間內依次
寫入或讀出資料.
Normal Mode Burst Mode
Buffer <---Bank 1 Buffer <-----Bank 1
<---Bank 2
<--Bank 1
<-Bank 2
Timing
Addr <Row><Col>
Data <Data>
burst
Addr <Row><Col>
Data <Data><Data><Data><Data>
以基本Latency差不多的DRAM而言,晶片組
在66MHZ外頻下使用Fast Paged Mode
可以達到X-3-3-3的Timing.使用EDO RAM可以達到
X-2-2-2.而使用burst EDO可以達到X-1-1-1.
(以上是讀取,寫入都比較慢)
但是Burst EDO只存在少量以及短時間.而立即被JEDEC SDRAM取代.
JEDEC SDRAM同樣也是利用internal bank而支援burst Mode.
==============================================
你不想休息嗎?我都想了
==============================================
SDRAM:採用同步傳輸
介紹SDRAM之前要先定義好SDRAM是什麼.是不是如字面上
一樣.採用Synchoronos transfer的就算嗎?不.事實上Rambus
跟1T-SRAM也都是同步傳輸.一般說的SDRAM指的是JEDEC SDRAM.
包含在PC66/PC100/PC133下的SDR SDRAM.DDR SDRAM,DDRII SDRAM
等.也有許多基於相關標準的衍生型,如SGRAM,GDDR/2/3,Enhanced
SDRAM(又稱為cached SDRAM,也就是加入SRAM為cache..另外也有
Enhanced/Cached EDO),NEC的Virtual Channel(PC133/DDR/DDR2)
等..
所以,一般稱的DDR RAM是不是JEDEC SDRAM?當然是.
只是在DDR SDRAM未出來之前,當然PC66/PC100/PC133
那時都直接稱為SDRAM,在DDR SDRAM出現之後為了區分
才將它們稱為SDR SDRAM.不過稱DDR SDRAM是SDRAM的一種
或者是SDRAM的演進/改良仍然沒錯.
synchronous bus ?
同步傳輸介面指的是什麼意思?與非同步Asynchronous的差異?
簡單一點的比喻,就好像一堆人合作作事情.
非同步傳輸:
A做好後通知B,C等待B完成後才開始作,D等待A以及C兩個
人一起通知它開始做事etc.....
同步傳輸:
所有人都事先收到一份嚴格規定好的行程表(timing diagram)
隨著時間的進行(clock).在行程表內定好的時間一定會完成.
沒達成的就地處決(........有嗎??)
效率上的差異是很明顯的.
可是SDRAM只是把DRAM改成synchronous介面嗎?
很不幸的,如果只是這樣做對效率一點幫助都沒有.雖然
如FPM DRAM及EDO RAM是非同步介面.但是主機板晶片組或者是
顯示晶片上的記憶體控制器存取它們仍然是照著固定的Timing
如6-3-3-3,4-1-1-1,只是需要依照外頻以及RAM的規格手動設定
不同的timing.......
JEDEC SDRAM主要的加速機制仍然發揚了過去有的方法.
省略重複的Row Addr,傳輸Col Addr可以與資料讀寫同時進行,
Burst Mode等..前面簡介過的方法都以另外一種形式在JEDEC
SDRAM上實作.
除此之外JEDEC SDRAM還有Mode Register可以動態改變
SDRAM的存取方式,burst length,各種相關的timing如CL等.
(Mode Registry和SPD不要混淆,作用算是相反吧)
====================================================
最早的SDRAM並沒有SPD
====================================================
JEDEC PC66/PC100/P133 SDRAM在介面上增加了BA(Bank
Address),以指定internal bank,SDR SDRAM有2組internal
bank,DDR SDRAM有4組.
internal bank
Bank 0 Bank 1
v v
Control |-------------| ----|
Logic --> | Bank 0 array| nk1 |
| | |
|-------------|-----|
|Sense Amp | Amp |
--------------------|
Buffer
所以SDRAM存取的時候會碰到三種情況.
1.在同一個page/row中(同一個row中的位址稱為page).
Timing :
CL-1-1-1...傳到burst length結束,SDRAM支援1/2/4/8
(CL=Cas Latency) 以及page結束這幾種
2.不同的row address.沒有bank conflict
RtC-CL-1-1-1...
(Ras to CAS latency)
3.不同的row address而碰上bank conflict.
該bank正在使用中
Precharge-RtC-CL-1-1-1....
而三者發生的機率.除了應用程式的種類外,memory controller
的規劃以及整個記憶體系統的配置(SDRAM不是拼命把記憶體頻寬
加大或是增加多通道效率就會持續增加的)都會有影響.最佳化
記憶體系統.對SDRAM來講可能就是平均有效傳輸速率33%與66%
的差異.
比如說以CL,RtC,Precharge都是3cycle的SDRAM來說
(其實哪裡有這麼好的??),burst length=4,那麼有效傳輸比例
分別是66%,44%,33%.但是memory系統的排程決定了三者的機率.
尤其是效率的bank conflict,在不同的情況下比例可以由5%
到25%以上不等.
Latency:貨真價實的效能障礙.
相對於DRAM密度的快速成長.DRAM對於存取的latency
卻是緩慢的改進.DRAM密度以符合電晶體密度的標準(1.5X/year)
成長的同時,DRAM latency的改進卻不到每年7%.
也就是說,看的到的RAM,雖然好像PC133跳DDR400,DDR2-533,
或者GDDR3 1.xGHZ等.可是真正的latency沒改進的情況下,採用的
是如同更多的internal bank去實作,得到的是更低的有效傳輸比例
.效能改進並沒有如同帳面數字一般.
=====================================
待續: DDR2
DirectRambus
1T-SRAM
Embedded DRAM
記憶體系統的設置參數對效能的影響
改進記憶體存取的軟體技巧
=====================================
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※ 編輯: eola 來自: 140.113.23.107 (02/06 04:32)
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