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Review and future prospects of low-voltage RAM circuits (2003)
| Citations: | 11 - 0 self |
BibTeX
@MISC{Nakagome03reviewand,
author = {Y. Nakagome and M. Horiguchi and T. Kawahara and K. Itoh},
title = {Review and future prospects of low-voltage RAM circuits},
year = {2003}
}
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Abstract
This paper describes low-voltage random-access memory (RAM) cells and peripheral circuits for standalone and embedded RAMs, focusing on stable operation and reduced subthreshold current in standby and active modes. First, technology trends in low-voltage dynamic RAMs (DRAMs) and static RAMs (SRAMs) are reviewed and the challenges of lowvoltage RAMs in terms of cell signal charge are clarified, including the necessary threshold voltage, V T , and its variations in the MOS field-effect transistors (MOSFETs) of RAM cells and sense amplifiers, leakage currents (subthreshold current and gate-tunnel current), and speed variations resulting from design parameter variations. Second, developments in conventional RAM cells and emerging cells, such as DRAM gain cells and leakage-immune SRAM cells, are discussed from the viewpoints of cell area, operating voltage, and leakage currents of MOSFETs. Third, the concepts proposed to date to reduce subthreshold current and the advantages of RAMs with respect to reducing the subthreshold current are summarized, including their applications to RAM circuits to reduce the current in standby and active modes, exemplified by DRAMs. After this, design issues in other peripheral circuits, such as sense amplifiers and low-voltage supporting circuits, are discussed, as are power management to suppress speed variations and reduce the power of power-aware systems, and testing. Finally, future prospects based on the above discussion are examined. 1.
Keyphrases
future prospect low-voltage ram circuit peripheral circuit leakage current speed variation active mode sense amplifier ram cell cell signal charge leakage-immune sram cell technology trend stable operation dram gain cell design issue cell area necessary threshold voltage low-voltage dynamic ram mo field-effect transistor design parameter variation low-voltage random-access memory conventional ram cell lowvoltage ram power management power-aware system static ram
