Sayeed Ahmad

Single-Ended Schmitt-Trigger-Based Robust Low-Power SRAM Cell

This paper presents a Schmitt-trigger-based single-ended 11T SRAM cell, which significantly improves read and write static noise margin (SNM) and consumes low power. Simulation results show that the cell also achieves the lowest leakage power dissipation among the cells considered for comparison. We also investigate the impact of process, voltage, and temperature variations on various performance parameters, such as hold SNM, read SNM, write margin, immunity to half-select issue, ION/IOFF ratio of read path, and leakage power of the cell; Monte Carlo simulation results confirm the robustness of the proposed cell toward these issues. Layout drawn in a 45-nm technology rule shows that the proposed cell occupies 2.02× greater area as compared with 6T SRAM cells. However, 6.9× higher ION/IOFF ratio of the read path of the proposed cell as compared with 6T cell holds potential to significantly subside the area overhead. A new figure of merit that comprehensively captures stability, delay, power dissipation, and area of an SRAM cell is also proposed. Based on the proposed metric, we observe that the proposed cell outperforms all, but one of the SRAM cells considered in this paper.

Low Leakage Single Bitline 9T (SB9T) Static Random Access Memory

This paper presents a low leakage, half-select free SB9T SRAM cell with good static and dynamic read/write performance along with smaller area. The proposed cell offers high Read SNM and low leakage power among the cells considered in this work while causing an area overhead of only 37% of that of 6T cell. Simulation results show that the proposed cell offers 4.2x higher RSNM, 33% lower mean leakage power as compared to 6T SRAM. The proposed cell also offers more than 10x higher Ion/Ioff ratio that holds potential to compensate for the area overhead by having more number of cells connected to the same bitline. The proposed cell has longer write delay because of the single bitline structure; however, it offers lower read delay and smaller read/write power to that of the 6T cell. Monte Carlo simulations using HSPICE at 16nm technology were performed by incorporating local and global variations and it is observed that the proposed cell offers high robustness against process variations. Therefore, the proposed cell could be a good choice for applications that demand high stability, low power, low area and moderate speed.

Simulation for Performance Analysis of Grid-Connected Induction Generators with Input Voltage Control

With the increasing application of wind energy, various technologies are developed for analyzing the performance of grid-connected induction generator (GIG) based wind energy conversion systems (WECSs). Input voltage control is one among them. In the paper, a simulation of input voltage control is done for analyzing the performance of grid-connected induction generators (GIGs). A digital simulation model of the input voltage control and its control system models are developed with MATLAB. An optimum value of input voltage is obtained using the simulation model such that maximum power is fed from induction generator to grid for a particular input mechanical torque and a series of studies on power flow from induction generator to power system or grid is carried out with this model. The improvement in power factor, efficiency and stator current are realized over a limited range of input mechanical torque (or wind speed). Also, the response characteristics of power flow under various wind conditions are also discussed.