A 45 nm 2-port 8T-SRAM using hierarchical replica bitline technique with immunity from simultaneous R/W access issues

Satoshi Ishikura; Marefusa Kurumada; Toshio Terano; Yoshinobu Yamagami; Naoki Kotani; Katsuji Satomi; Koji Nii; Makoto Yabuuchi; Yasumasa Tsukamoto; Shigeki Ohbayashi; Toshiyuki Oashi; Hiroshi Makino; Hirofumi Shinohara; Hironori Akamatsu

doi:10.1109/JSSC.2008.917568

A 45 nm 2-port 8T-SRAM using hierarchical replica bitline technique with immunity from simultaneous R/W access issues

Satoshi Ishikura^*, Marefusa Kurumada, Toshio Terano, Yoshinobu Yamagami, Naoki Kotani, Katsuji Satomi, Koji Nii, Makoto Yabuuchi, Yasumasa Tsukamoto, Shigeki Ohbayashi, Toshiyuki Oashi, Hiroshi Makino, Hirofumi Shinohara, Hironori Akamatsu

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

31 Citations (Scopus)

Abstract

We propose a new -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_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 (RAV) 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 [1]. The memory cell size is 0.597 μm³, This 2-port SRAM macro achieves 7 times faster access time without misreading.

Original language	English
Pages (from-to)	938-943
Number of pages	6
Journal	IEEE Journal of Solid-State Circuits
Volume	43
Issue number	4
DOIs	https://doi.org/10.1109/JSSC.2008.917568
Publication status	Published - 2008 Jan
Externally published	Yes

Keywords

2-port SRAM
8T cell
Hierarchical bit line
Misread
Simultaneous read/ write access
Single bit line

ASJC Scopus subject areas

Electrical and Electronic Engineering

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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. (2008). A 45 nm 2-port 8T-SRAM using hierarchical replica bitline technique with immunity from simultaneous R/W access issues. IEEE Journal of Solid-State Circuits, 43(4), 938-943. https://doi.org/10.1109/JSSC.2008.917568

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 2008, 'A 45 nm 2-port 8T-SRAM using hierarchical replica bitline technique with immunity from simultaneous R/W access issues', IEEE Journal of Solid-State Circuits, vol. 43, no. 4, pp. 938-943. https://doi.org/10.1109/JSSC.2008.917568

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abstract = "We propose a new -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 (Vt) 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 (RAV) 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 [1]. The memory cell size is 0.597 μm3, This 2-port SRAM macro achieves 7 times faster access time without misreading.",

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AU - Kotani, Naoki

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AU - Nii, Koji

AU - Yabuuchi, Makoto

AU - Tsukamoto, Yasumasa

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AB - We propose a new -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 (Vt) 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 (RAV) 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 [1]. The memory cell size is 0.597 μm3, This 2-port SRAM macro achieves 7 times faster access time without misreading.

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A 45 nm 2-port 8T-SRAM using hierarchical replica bitline technique with immunity from simultaneous R/W access issues

Abstract

Keywords

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