1. Memory Semiconductor Memory Classification ETEG 431 SG Size: Bits, Bytes, Words. Timing Parameter: Read, Write Cycle… Function: ROM, RWM, Volatile, Static, … Access Pattern: RAM, FIFO, LIFO,… Input/Output Architecture : Multiport… Application: Embedded, Secondary, …

2. Memory Semiconductor Memory Classification ETEG 431 SG Read-Write Memory Non-Volatile Read-Write Memory Read-Only Memory EPROM E 2 PROM FLASH Random Access Non-Random Access SRAM DRAM Mask-Programmed Programmable (PROM) FIFO Shift Register CAM LIFO

3. Memory Memory Architectures ETEG 431 SG N-word memory N-word memory M-bits M-bits Select bits (S o -S N-1 ) Select bits (S o -S N-1 ) Good for Small Memories Good for Small Memories Not for Large ones Not for Large ones Too many Select Signals Too many Select Signals M bits Word 0 Word 1 Word 2 WordN 2 2 N 2 1 Storage cell N words S 0 S 1 S 2 S N 2 2 S N 2 1 Input-Output (M bits)

4. Memory Memory Architectures: Decoder ETEG 431 SG K address bits N = 2 K Decoder reduces the number of select signals

5. Memory Memory Architectures: Decoder (Contd.) ETEG 431 SG Reduces the number of external address lines. Memory Aspect Ratio??? Shape of storage cell is approximately square. Excessively long vertical wires.

6. Memory Memory Architectures: Array ETEG 431 SG Amplify swing to rail-to-rail amplitude Selects appropriate word ll Aspect ratio approaches Unity Logic swing, noise margin, fanout, …

7. Memory Hierarchical Memory Architecture ETEG 431 SG

8. Memory Hierarchical Memory Architecture (Contd..) ETEG 431 SG Larger Memories: Slower. Add one extra dimension. Block address. Shorter wires within blocks. Power Saving: Block address activates only one block.

9. Memory CMOS SRAM Cell ETEG 431 SG WL BL V DD M 5 M 6 M 4 M 1 M 2 M 3 BL Q Q 6 Transistor CMOS SRAM Cell

10. Memory CMOS SRAM: Read Operation ETEG 431 SG Pre-charge bit lines to … V DD /2. Assert the word line. Read Upset. Small sized cell: Very slow discharge. Sense Amplifier.

11. Memory CMOS SRAM: Write Operation ETEG 431 SG NMOS: Strong 0. Pull voltage below the threshold value.

12. Memory 1-T DRAM ETEG 431 SG