Static Noise Margin Evaluation Method Based on Direct Polynomial-Curve-Fitting with Universal SRAM Cell Inverter TEG Measurement

A new method to evaluate the static noise margin (SNM) for leading-edge CMOS SRAM development is proposed. This method includes: (1) direct measurement of the inverter DC transfer curves using a "universal SRAM cell inverter TEG (USCIT)" with arbitrary transistor ratios, (2) curve-fitting of the measured data to polynomial functions in a 45-degree rotated space, and (3) a database of the polynomial coefficients to evaluate and optimize the SNM by a simple algebraic operation. The SNM values obtained using this method are in good agreement with the measured SRAM operations.