A configurable SRAM with constant-negative-level write buffer for low-voltage operation with 0.149µm<sup>2</sup> cell in 32nm high-<inf>k</inf> metal-gate CMOS

Abstract

This paper presents a configurable SRAM for low-voltage operation with constant-negative-level write buffer (CNL-WB) and level programmable wordline driver for single supply (LPWD-SS) operation. CNL-WB is suitable for compilable SRAMs and it improves write margin by featuring an automatic BL-level adjustment for configuration range of four to 512 cells/BL using a replica-BL technique. LPWD-SS optimizes the tradeoff between disturb and write margin of a memory cell, allowing a 60% shorter WL rise time than that of the conventional design [1] at 0.7V. A test-chip is fabricated in a 32nm high- <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</inf> metal-gate CMOS technology with a 0.149µm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 6T-SRAM cell. Measurement results demonstrate a cell-failure rate improvement of two orders of magnitude for an array-configuration range of 64 to 256 rows by 64 to 256 columns.