On-Line Stability Detectors for Sequential Circuit Elements

I conducted this study of on-line stability detectors to learn more about stability checking in VLSI circuitry and how I varied the conditions in order to try to find trends on how well the stability detectors work each set of conditions. I varied the clock speed, temperature, transistor feature size, and sizing of the transistors in both Franco’s Stability Checker and Yada’s MSC Cell from papers [3] and [5] respectively. I found that the sizing has the greatest impact on both test stability detectors and that both stability detectors can work under a variety of conditions with little to no loss in functionality. I did notice, however, that in general lower temperatures and smaller feature sizes produce better performance under most conditions. For Franco’s detector, a smaller error pullup transistor results in better error detection while a larger pullup transistor allows for better setup times. For the MSC Cell, smaller transistors resulted in better performance

Coset Coding to Extend the Lifetime of Non-Volatile Memory

<p>Modern computing systems are increasingly integrating both Phase Change Memory (PCM) and Flash memory technologies into computer systems being developed today, yet the lifetime of these technologies is limited by the number of times cells are written. Due to their limited lifetime, PCM and Flash may wear-out before other parts of the system. The objective of this dissertation is to increase the lifetime of memory locations composed of either PCM or Flash cells using coset coding. </p><p>For PCM, we extend memory lifetime by using coset coding to reduce the number of bit-flips per write compared to un-coded writes. Flash program/erase operation cycle degrades page lifetime; we extend the lifetime of Flash memory cells by using coset coding to re-program a page multiple times without erasing. We then show how coset coding can be integrated into Flash solid state drives.</p><p>We ran simulations to evaluate the effectiveness of using coset coding to extend PCM and Flash lifetime. We simulated writes to PCM and found that in our simulations coset coding can be used to increase PCM lifetime by up to 3x over writing un-coded data directly to the memory location. We extended the lifetime of Flash using coset coding to re-write pages without an intervening erase and were able to re-write a single Flash page using coset coding more times than when writing un-coded data or using prior coding work for the same area overhead. We also found in our simulations that using coset coding in a Flash SSD results in higher lifetime for a given area overhead compared to un-coded writes.</p>Dissertatio