Next-Generation SRAM: Design and Optimization with Carbon Nanotubes

Static random access memory (SRAM) product for advanced space applications must demonstrate high performance to meet the ever increasing data rates of space systems and must be radiation hardened to ensure unfettered, reliable operation in the harsh environments of outer space. High performance and radiation hardness are not mutually exclusive. The challenge confronting present day SRAM development is to concurrently achieve both of these objectives. An SRAM design evaluation methodology is described that uncovers limitations on performance, facilitating the identification of both the limiting mechanisms and the corrective design enhancements. Simulation model to hardware measurement correlation on two designs of radiation tolerant 4 M SRAM product validates the evaluation methodology. The evaluation methodology described herein can be Universally applied to any SRAM design to ensure that the highest performance potential of the design is realized.

Carbon nanotube field-effect transistor (CNTFET) is envisioned as a promising device to overcome the limitations of traditional CMOS based MOSFETs due to its favourable physical properties. This paper presents a novel six-transistor (6T) static random access memory (SRAM) bitcell design using CNTFETs. Extensive validations and comparative analyses are carried out with the proposed SRAM design using SPICE based simulations. We show that the proposed CNTFET based SRAM has a significantly better static noise margin (SNM) and write ability margin (WAM) compared to a CNTFET-based standard 6T bitcell, equivalent to isolated read-port 8T cell based on CNTFET, while consuming less dynamic power. We further demonstrate that it exhibits higher robustness under process, voltage and temperature (PVT) variations when compared with the traditional CMOS SRAM cell designs. Furthermore, metallic CNTs removal technique is used considering metallic tolerance to make the proposed SRAM design more reliable.

This paper proposes a new asymmetric underlap Fin-Field Effect Transistor (FinFET) structure using a dual- k spacer. Asymmetric dual-spacer at source shows excellent gate control over the channel due to increase in the outer fringe field at gate/source underlap. Hence, this structure exhibits a superior short-channel effect metric over the conventional/single-spacer underlap FinFET. The proposed asymmetric structure enhances static random access memories (SRAMs) performance in terms of robustness, access times as well as leakage power during the hold, read, and write operations. The hold static noise margin and write margin increases by 5.16% and 5.66%, respectively. The read stability enhances by 13.75% and 19.35% over conventional FinFET SRAM circuit. Furthermore, the leakage power reduces by 60%, and write access time improves by 23.63%. Compared with conventional FinFET-based SRAM, same bit-cell area and read delay are associated with the proposed structure. Supply voltage scalability on SRAM design metrics is also investigated. In addition to SRAM application, underlap length, lateral source/drain doping gradient, and the high- k spacer width are optimized for high-performance digital applications.

Static Random Access Memory (SRAM) technology is the latest technology must advance to satisfy the high-speed performance and low power consumption requirements of contemporary devices. The design, testing, and validation of SRAM cells with configurations ranging from six transistors (6T) to ten transistors (10T) are thoroughly examined in this research work. The study's main goal is to pinpoint the crucial elements that affect SRAM cell performance, such as data retention voltages, power consumption, delay factors, stability measures, and noise margins. Existing SRAM designs and their drawbacks are assessed through a thorough literature review, emphasizing the need for innovative SRAM design techniques. The process includes a thorough examination of important variables and the design and testing of several SRAM cell designs using sophisticated simulation tools. To guarantee robustness and reliability, every design from 6T to 10T is painstakingly created, simulated, and verified against a series of predetermined scenarios. The findings show how several SRAM layouts compare in terms of power efficiency, delay, stability, noise margin, and area efficiency. The study's conclusions offer helpful recommendations for improving SRAM designs in the future by weighing the trade-offs between stability, speed, and power consumption. By providing tested design methodologies that improve the performance and efficiency of SRAM cells, this research makes a substantial contribution to the field of semiconductor technology and meets the expanding demands of contemporary electronic gadgets.

Carbon nanotube field-effect transistor (CNTFET) is envisioned as a promising device to overcome the limitations of traditional CMOS based MOSFETs due to its favourable physical properties. This paper presents a novel six-transistor (6T) static random access memory (SRAM) bitcell design using CNTFETs. Extensive validations and comparative analyses are carried out with the proposed SRAM design using SPICE based simulations. We show that the proposed CNTFET based SRAM has a significantly better static noise margin (SNM) and write ability margin (WAM) compared to a CNTFET-based standard 6T bitcell, equivalent to isolated read-port 8T cell based on CNTFET, while consuming less dynamic power. We further demonstrate that it exhibits higher robustness under process, voltage and temperature (PVT) variations when compared with the traditional CMOS SRAM cell designs. Furthermore, metallic CNTs removal technique is used considering metallic tolerance to make the proposed SRAM design more reliable.

The growing demand for low-power static random access memory (SRAM) cells in Internet of Things (IoT) devices has led to the development of various SRAM cell topologies that minimize power consumption while maintaining performance and stability. In this paper, we have analyzed various SRAM designs based on different parameters, such as power dissipation, delay, area, energy, and stability. It is observed that 6T SRAM cell, consisting of six transistors, is the most widely used topology due to its simplicity and low area requirements. However, larger cells such as 8T,9T, and 10T have been developed to improve stability and reduce power consumption, although they require more area. It has been observed8 T work better for read delay while 9T works better for 9 Scaling down SRAM cells to smaller feature sizes presents challenges in maintaining stability and reliability while minimizing power consumption.

Application of quantum-dot cellular automata (QCA) technology as an alternative to CMOS technology on the nanoscale has a promising future; QCA is an interesting technology for building memory. The proposed design and simulation of a new memory cell structure based on QCA with a minimum delay, area, and complexity is presented to implement a static random access memory (SRAM). This paper presents the design and simulation of a 16-bit $\times 32$ -bit SRAM with a new structure in QCA. Since QCA is a pipeline, this SRAM has a high operating speed. The 16-bit $\times 32$ -bit SRAM has a new structure with a 32-bit width designed and implemented in QCA. It has the ability of a conventional logic SRAM that can provide read/write operations frequently with minimum delay. The 16-bit $\times 32$ -bit SRAM is generalized and an $n\times 16$ -bit $\times 32$ -bit SRAM is implemented in QCA. Novel 16-bit decoders and multiplexers (MUXs) in QCA are presented that have been designed with a minimum number of majority gates and cells. The new SRAM, decoders, and MUXs are designed, implemented, and simulated in QCA using a signal distribution network to avoid the coplanar problem of crossing wires. The QCA-based SRAM cell was compared with the SRAM cell based on CMOS. Results show that the proposed SRAM is more efficient in terms of area, complexity, clock frequency, latency, throughput, and power consumption.

Variability-aware 7T SRAM circuit with low leakage high data stability SLEEP mode

This paper combines several low-leakage and low-cost techniques to design multi-port static random access memory (SRAM) for register file in a vertex shader processor for OpenGL ES 2.0 graphics applications. First, precharge control is employed to eliminate unnecessary precharge operations. Then, dynamic forward body-bias control for leakage reduction is proposed to adjust the threshold voltage of transistors depending on whether memory cell is accessed or idle. Different power-gating methods are presented for SRAM cells and for sense amplifiers. The thin-cell-like lithography-friendly layout style is adopted for the multi-port SRAM cell to achieve more compact and flexible layout with easy addition of read ports. The cross-coupled inverters in the SRAM cell have asymmetric design to reduce area and also increase the writability. A 32×128-bit register file supporting 5-read and 1-write operations is implemented and verified, which has smaller area and lower leakage compared with that from ARM register file generator.

More than 10,000 carbon nanotube field-effect transistors (CNTFETs) have been successfully integratedinto one semiconductor chip using conventional semiconductor design procedures and manufacturing processes. Thesetransistors offer advantages such as high carrier mobility, large saturation velocity, low intrinsic capacitance, flexibility, andtransparency. The three-dimensional multilayer structure of the CNTFET semiconductor chip, along with ongoing researchin CNTFET manufacturing processes, increases the potential for creating a hybrid MOSFET-CNTFET semiconductorchip. This chip combines conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) and CNTFETs inone integrated system. This paper discusses a methodology to design 6T binary static random-access memory (SRAM)using a hybrid MOSFET-CNTFET. This paper introduces a method for designing a hybrid MOSFET-CNTFET SRAMby leveraging existing MOSFET SRAM or CNTFET SRAM design approaches. Additionally, this paper compares itsperformance with conventional MOSFET SRAM and CNTFET SRAM designs.

Carbon Nanotube Field Effect Transistor (CNFET) has emerged as an alternative material to silicon for high performance, high stability and low power Static Random Access Memory (SRAM) design in recent years. SRAM functions as cache memory in computers and many portable devices. Therefore, CNFET based SRAM cell design is desired for low standby power cache memory. In CNFET based six transistor SRAM cell, access transistors contribute significantly to the leakage power during standby mode. This paper proposes a technique to reduce the standby power of SRAM by scaling the channel length of access transistor. An optimum channel length is selected using HSPICE simulation to ensure best performance in terms of stability, standby power and write time. The proposed design results in 37.2% and 40.6% improvements in standby power and static noise margin (SNM) respectively compared to the conventional CNFET SRAM cell with minimal write time trade off.

-As the demand for low-power, high-performance memory systems grows, the design of efficient SRAM (Static Random Access Memory) cells becomes increasingly crucial. This paper explores the power consumption, performance, and stability of two SRAM cell designs: the conventional 6T and the Single Ended 6T SRAM. While the conventional 6T SRAM is prone to read disturb noise and high leakage power, it remains widely used due to its simplicity and compactness. To address these issues, the Single Ended 6T SRAM cell is introduced as an alternative, which reduces both power consumption and area while maintaining competitive performance. The study provides a detailed analysis of static and dynamic power consumption, read/write stability, and overall energy efficiency for both cell architectures. Simulation results show that the Single Ended 6T SRAM offers significant improvements in power reduction without compromising speed, making it a promising solution for future low-power, high-performance memory applications. Keywords— SRAM cell, Pre-Charge Circuits, Sense Amplifiers, and Single-Ended vs. Conventional 6T SRAM Cell.

<p>Today’s era is a digital world where each and every section of the society is experiencing and encountering with semiconductor chips. In very large-scale integration (VLSI) circuits the design of static random-access memory (SRAM) plays a crucial role in ensuring both low-power consumption and high-speed performance. The sense amplifiers (SA) are integral parts for information accessing storage in SRAM IC design. This paper introduces a dual voltage latch sense amplifier (DVLSA) for SRAM integrated circuits (IC). The comparative analyses of various SA are studied and then design a low-power SA through the implementation of energy-efficient technique. Further, we have elucidated the causes of delay and power dissipation in different SA with useful solutions and performance evaluation is conducted by comparing the proposed design with existing SA reported in the literature. The performance parameters such as power 1.604 uw, energy 470.50 fJ, delay 80.04 ps, and current 5.406 are scrutinized to assess the efficiency of the designs. The cell outcomes have been validated with cadence tool on 180 nm technology and operate at 1.8 V. The proposed design, namely, DVLSA demonstrates minimal energy consumption and low power dissipation, making it a promising advancement in SRAM IC technology.</p>

Wide-spread availability of high-speed INTERNET and rapid increase of smart-phone users have significantly increased online video surfing. Video decoders like H.264/H.265/MPEG consume a significant amount of power in Static Random Access Memory (SRAM) buffers. In this study, the authors propose a 1 kb (32 × 32) heterogeneous 8T SRAM architectures with (2-lower order bits) and without truncation for H.264 video decoder. They have used heterogeneous sized SRAM design and bit-truncation techniques are used simultaneously to obtain low power memory design for the H.264 video decoder. They show that the proposed approximate memory used for H.264 video decoder provide high video quality even at low power and low area budget of 0.3 µW/pixel and 5.2 µm 2 /pixel, respectively, at 0.5 V and 20 MHz in UMC 28 nm CMOS technology. The proposed memory architecture is compared with existing approximate memories such as heterogeneous 6T, hybrid 8T/6T, all-identical 6T, and all-identical 8T SRAM memory. The results show that proposed memory architectures perform cumulatively better than existing techniques in terms of dynamic power, leakage power, and area.

A high-speed low-power novel architecture of Dual Bit Content Addressable Memory (DB-CAM) is reported in this article. A low leakage, low power and high-speed memory has been developed using the novel architecture of DB-CAM that can store 2 bits in a single CAM block and Static Random Access Memory (SRAM). Data search operation is done by using CAM cells and SRAMs are used as data storage cells. The output of SRAM cells depend on the search result of CAM cells. To make the search operation more precise a priority detector circuit has been proposed. The new architecture of DB-CAM block reduces the power consumption, transistor count and the area on chip enormously. The functionality of these circuits was checked and performance parameters like propagation delay and dynamic power consumption were calculated by spice spectre (CADENCE) using standard 90 nm CMOS technology.