Abstract: A method for evaluating leakage effects on static memory cell access time provides a mechanism for raising the performance of memory arrays beyond present levels/yields. By altering the states of other static memory cells connected to the same bitline as a static memory cell under test, the effect of leakage on the access time of the cell can be observed. The leakage effects can further be observed while varying the internal symmetry of the memory cell, operating the cell and observing changes in performance caused by the asymmetric operation. The asymmetry can be introduced by splitting one or both power supply rail inputs to the cell and providing differing power supply voltages or currents to each cross-coupled stage.

Abstract: Bitline variable methods and circuits for evaluating static memory cell dynamic stability provide a mechanism for raising the performance of memory arrays beyond present levels/yields. By altering the bitline pre-charge voltage of a static random access memory (SRAM) memory cell, operating the cell and observing changes in performance caused by the changes in the bitline voltage, the dynamic stability of the SRAM cell can be studied over designs and operating environments. Alternatively or in combination, the loading at the outputs of the cell can altered in order to affect the performance of the cell. In addition, cell power supply voltages can be split and set to different levels in order to study the effect of cell asymmetry in combination with bitline pre-charge voltage differences.

Abstract: A memory cell having an asymmetric connection for evaluating dynamic stability provides a mechanism for raising the performance of memory arrays beyond present levels/yields. By operating the cell and observing changes in performance caused by the asymmetry, the dynamic stability of the SRAM cell can be studied over designs and operating environments. The asymmetry can be introduced by splitting one or both power supply rail inputs to the cell and providing differing power supply voltages or currents to each crosscoupled stage. Alternatively or in combination, the loading at the outputs of the cell can altered in order to affect the performance of the cell. A memory array with at least one test cell can be fabricated in a production or test wafer and internal nodes of the memory cell can be probed to provide further information.

Abstract: An internally asymmetric method for evaluating static memory cell dynamic stability provide a mechanism for raising the performance of memory arrays beyond present levels/yields. By altering the internal symmetry of a static random access memory (SRAM) memory cell, operating the cell and observing changes in performance caused by the asymmetric operation, the dynamic stability of the SRAM cell can be studied over designs and operating environments. The asymmetry can be introduced by splitting one or both power supply rail inputs to the cell and providing differing power supply voltages or currents to each cross-coupled stage. Alternatively or in combination, the loading at the outputs of the cell can altered in order to affect the performance of the cell. A memory array with at least one test cell can be fabricated in a production or test wafer and internal nodes of the memory cell can be probed to provide further information.

Abstract: A ring oscillator row circuit for evaluating memory cell performance provides for circuit delay and performance measurements in an actual memory circuit environment. A ring oscillator is implemented with a row of memory cells and has outputs connected to one or more bitlines along with other memory cells that are substantially identical to the ring oscillator cells. Logic may be included for providing a fully functional memory array, so that the cells other than the ring oscillator cells can be used for storage when the ring oscillator row wordlines are disabled. One or both power supply rails of individual cross-coupled inverter stages forming static memory cells used in the ring oscillator circuit may be isolated from each other in order to introduce a voltage asymmetry so that circuit asymmetry effects on delay can be evaluated.

Abstract: Internally asymmetric methods and circuits for evaluating static memory cell dynamic stability provide a mechanism for raising the performance of memory arrays beyond present levels/yields. By altering the internal symmetry of a static random access memory (SRAM) memory cell, operating the cell and observing changes in performance caused by the asymmetric operation, the dynamic stability of the SRAM cell can be studied over designs and operating environments. The asymmetry can be introduced by splitting one or both power supply rail inputs to the cell and providing differing power supply voltages or currents to each cross-coupled stage. Alternatively or in combination, the loading at the outputs of the cell can altered in order to affect the performance of the cell. A memory array with at least one test cell can be fabricated in a production or test wafer and internal nodes of the memory cell can be probed to provide further information.