A 45 nm 2-port 8T-SRAM Using Hierarchical Replica Bitline Technique With Immunity From Simultaneous R/W Access Issues
- Resource Type
- Periodical
- Authors
- Ishikura, S.; Kurumada, M.; Terano, T.; Yamagami, Y.; Kotani, N.; Satomi, K.; Nii, K.; Yabuuchi, M.; Tsukamoto, Y.; Ohbayashi, S.; Oashi, T.; Makino, H.; Shinohara, H.; Akamatsu, H.
- Source
- IEEE Journal of Solid-State Circuits IEEE J. Solid-State Circuits Solid-State Circuits, IEEE Journal of. 43(4):938-945 Apr, 2008
- Subject
- Components, Circuits, Devices and Systems
Engineered Materials, Dielectrics and Plasmas
Computing and Processing
Random access memory
System-on-a-chip
Circuits
Degradation
Fabrication
Threshold voltage
CMOS process
CMOS technology
Large scale integration
High K dielectric materials
Hierarchical bit line
misread
simultaneous read/write access
single bit line
2-port SRAM
8T cell
- Language
- ISSN
- 0018-9200
1558-173X
We propose a new 2-port SRAM with a single read bit line (SRBL) eight transistors (8T) memory cell for a 45 nm system-on-a-chip (SoC). Access time tends to be slower as a fabrication is scaled down because of threshold voltage ($V_{\rm t}$) random variations. A Divided read Bit line scheme with Shared local Amplifier (DBSA) realizes fast access time without increasing area penalty. We also show an additional important issue of a simultaneous Read and Write (R/W) access at the same row by using DBSA with the SRBL-8T cell. A rise of the storage node causes misreading. A Read End detecting Replica circuit (RER) and a Local read bit line Dummy Capacitance (LDC) are introduced to solve this issue. A 128 bit lines—512 word lines 64 kb 2-port SRAM macro using these schemes was fabricated by a 45 nm bulk CMOS low-standby-power (LSTP) CMOS process technology . The memory cell size is 0.597 $\mu{\hbox {m}}^{2}$. This 2-port SRAM macro achieves 7 times faster access time without misreading.