Ho, Yenpo (2008-05). Dynamic stability margin analysis on SRAM. Master's Thesis. Thesis uri icon

abstract

  • In the past decade, aggressive scaling of transistor feature size has been a primary force driving higher Static Random Access Memory (SRAM) integration density. Due to the scaling, nanometer SRAM designs are getting more and more stability issues. The traditional way of analyzing stability is the Static Noise Margins (SNM). However, SNM has limited capability to capture critical nonlinearity, so it becomes incapable of characterizing the key dynamics of SRAM operations with induced soft-error. This thesis defines new stability margin metrics using a system-theoretic approach. Nonlinear system theories will be applied rigorously in this work to construct new stability concepts. Based on the phase portrait analysis, soft-error can be explained using bifurcation theory. The state flipping requires a minimum noise current (Icritical) and time (Tcritical). This work derives Icritical analytically for simple L1 model and provides design insight using a level one circuit model, and also provides numerical algorithms on both Icritical and Tcritial for higher a level device model. This stability analysis provides more physical characterization of SRAM noise tolerance property; thus has potential to provide needed yield estimation.
  • In the past decade, aggressive scaling of transistor feature size has been a primary
    force driving higher Static Random Access Memory (SRAM) integration density. Due to
    the scaling, nanometer SRAM designs are getting more and more stability issues. The
    traditional way of analyzing stability is the Static Noise Margins (SNM). However, SNM
    has limited capability to capture critical nonlinearity, so it becomes incapable of
    characterizing the key dynamics of SRAM operations with induced soft-error. This thesis
    defines new stability margin metrics using a system-theoretic approach. Nonlinear system
    theories will be applied rigorously in this work to construct new stability concepts. Based
    on the phase portrait analysis, soft-error can be explained using bifurcation theory. The
    state flipping requires a minimum noise current (Icritical) and time (Tcritical). This work
    derives Icritical analytically for simple L1 model and provides design insight using a level
    one circuit model, and also provides numerical algorithms on both Icritical and Tcritial for
    higher a level device model. This stability analysis provides more physical
    characterization of SRAM noise tolerance property; thus has potential to provide needed
    yield estimation.

publication date

  • May 2008