Memory Structures - Docència

Memory Structures

Ramon Canal NCD - Master MIRI

Slides based on:Introduction to CMOS VLSI Design. D. Harris

NCD - Master MIRI

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Outline

? Memory Arrays ? SRAM Architecture

? SRAM Cell ? Decoders ? Column Circuitry ? Multiple Ports

? Serial Access Memories

NCD - Master MIRI

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Memory Arrays

Memory Arrays

Random Access Memory

Serial Access Memory Content Addressable Memory (CAM)

Read/Write Memory (RAM)

(Volatile)

Read Only Memory (ROM)

Shift Registers

(Nonvolatile)

Queues

Static RAM (SRAM)

Dynamic RAM (DRAM)

Serial In Parallel Out

(SIPO)

Parallel In Serial Out

(PISO)

First In First Out (FIFO)

Last In First Out (LIFO)

Mask ROM

Programmable ROM

(PROM)

Erasable Programmable

ROM (EPROM)

Electrically Erasable Programmable

ROM (EEPROM)

Flash ROM

NCD - Master MIRI

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Array Architecture

? 2n words of 2m bits each

? If n >> m, fold by 2k into fewer rows of more columns

wordlines bitline conditioning bitlines

row decoder

memory cells: 2n-k rows x 2m+k columns

n-k k

n column decoder

2m bits

column circuitry

? Good regularity ? easy to design

? Very high density if good cells are used

NCD - Master MIRI

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12T SRAM Cell

? Basic building block: SRAM Cell

? Holds one bit of information, like a latch ? Must be read and written

? 12-transistor (12T) SRAM cell

? Use a simple latch connected to bitline ? 46 x 75 unit cell

bit write write_b read read_b

NCD - Master MIRI

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