SUMMARY

In this paper, a SRAM cell structure which uses pMOS access transistors and predischarged bitlines is presented. By using the strained pMOS transistor technology, the degradation of the read static noise margin (SNM) at high supply voltages due to the aging, especially in the presence of symmetric stress, is suppressed. In contrast to conventional cell, the write margin of the proposed cell does not degrade considerably at low supply voltages. To assess the efficacy, the proposed cell is compared with conventional cell for two cases of unstrained and strained pMOS. A comparative study is performed using mixed mode device/circuit simulations for a gate length of 22 nm. The results show that the read SNM degradation due to the symmetric aging at the supply voltage of 1 V is about 6% after three years for the proposed strained structure, while degradations are 14%, 12%, and 11% for the unstrained proposed structure, unstrained, and strained conventional structures, respectively. In addition, the proposed cell has both read and write cell sigma yields higher than six for supply voltages ranging from 1 V down to 0.5 V while the other structures have read or write yields less than six at the minimum supply voltage. Through some work function tuning, the cell sigma yields of the other structures reach above six for both read and write while being still lower than those of the proposed structure. Copyright © 2015 John Wiley & Sons, Ltd.

A FinFET SRAM cell design with BTI robustness at high supply voltages and high yield at low supply voltages

8755-3996/05/$20.00 ©2005 IEEE COMPOUND SEMICONDUCTOR INTEGRATED CIRCUITS By Tho T. Vu, World Scientific, 2003. This book is a collection of published papers. Some papers focus on difference and advantages of different compound semiconductor while others focus on the device strength on circuit design. As the intent of the compound semiconductor, the book covers high-speed applications, e.g., optical amplifier area. It is pleasing to see how different processes technologies are compared. The comparison ranges from device level-gm, vth, capacitance to circuit performance. In my opinion, the circuit performance comparison doesn’t seem quite fair since different design technique is applied for different technology. For example, traditional CMOS technology circuit design technique is different than those of GaAs. Few papers explain the characteristic of each compound semiconductor well. Basically, all the compound semiconductors are mentioned one way or the other in the book. Charts are plotted to see what happens to the device characteristics when the concentration of one element increases. The papers don’t cover much mathematical formulation. Instead, many simulation/experimental plots are shown. For those interested, the content of this book can be obtained from published papers. The book is a special issue of the International Journal of High Speed Electronics and Systems. COMMON WAVEFORM ANALYSIS—A NEW AND PRACTICAL GENERALIZATION OF FOURIER ANALYSIS By Y. Wei, Qishan Zhang, Yuchuan Wei, and Q. Zhang, Kluwer Academic Publishers, 2000. On many occasions, both academics and students look for mathematical background on subjects such as transforms, matrices, number theory, etc., and many books in print attempt to cater to these needs. Some books successfully present some subjects with sufficient details, while some present a bit of everything and fail in presenting the details of a given specific area. In the book Common Waveform Analysis—A New and Practical Generalization of Fourier Analysis, Wei and Zhang have selected and presented the analysis of square, triangular, and trapezoidal waves with sufficient details and the related mathematical theories behind the subjects. For a specific and a widely used topic such as Fourier series and with sufficient attention to the case of three common repetitive waveforms, the work is impressive in a mathematical sense. The presentation of number theory and frequency analysis based on general periodic functions enhances the value of the presentation for the academic or the student who is more inclined towards the analytical parts of the topic. One useful element for the busy senior academic is Chapter 5, which summarizes most other parts of the book and provides a snapshot approach to essentials of Fourier analysis. Square, triangular, and trapezoidal waveform analysis can be useful in many practical engineering and scientific environments, and this 160-page work is a good reference source for such a specific area. However, in a more modern sense of Fourier transform and associated analytical areas, the work does not provide any breadth or the depth, quite justifiably in such a specialized work. Personally I would love to see more references/bibliography in a work of this kind for more details and also for affiliated areas in a modern engineering sense. Nihal Kularatna,

D. Lingaiah

Papers

Echo Signal Processing [Book Review]