A Read-Disturb-Free, Differential Sensing 1R/1W Port, 8T Bitcell Array

作者：Kulkarni Jaydeep P^*; Goel Ashish; Ndai Patrick; Roy Kaushik

来源：IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2011, 19(9): 1727-1730.

DOI：10.1109/TVLSI.2010.2055169

• Differential sensing
• low voltage static random access memory (SRAM)
• 1R/1W port SRAM
• process tolerance
• 8-transistor (8T) bitcell

We propose a read-disturb-free, 1-read/1-write port, 8-transistor (8T) bitcell utilizing differential sensing. The conflicting design requirement of read versus write operation in a conventional 6T SRAM bitcell is eliminated using separate read/write access transistors. A distributed read-access transistor shared across the bitcells of every row enables read-disturb-free differential sensing operation with eight transistors per bitcell. Write-access transistors are upsized to form a diffusion-notch-free layout which would result in improved manufacturability. 1R/1W port nature of the proposed 8T bitcell makes it an attractive choice for the high speed, dense register file (RF) designs. Bitcell failure measurements on 20 test-chips fabricated in 90-nm CMOS technology demonstrate that the proposed differential 8T bitcell shows 220 mV lower read-V-min, 40 mV lower hold-V-min, 25 mV higher weak-write voltage compared to the iso-area 6T bitcell at iso-performance. At 600 mV, the proposed 8T bitcell array operates up to 67.2 MHz.

• 出版日期2011-9