6T Static Random Access Memory Cell Research Articles

Design of High-Speed Dual Port 8T SRAM Cell with Simultaneous and Parallel READ-WRITE Feature

An innovative 8 transistor (8T) static random access memory (SRAM) architecture with a simple and reliable read operation is presented in this study. LTspice software is used to implement the suggested topology in the 16nm predictive technology model (PTM). Investigations into and comparisons with conventional 6T, 8T, 9T, and 10T SRAM cells have been made regarding read and write operations' delay and power consumption as well as power delay product (PDP). The simulation outcomes show that the suggested design offers the fastest read operation and PDP optimization overall. Compared to the current 6T and 9T topologies, the noise margin is also enhanced. Finally, the comparison of the figure of merit (FoM) indicates the best efficiency of the proposed design.

Optimization Techniques for Reliable Low Leakage GNRFET-Based 9T SRAM

We present a low-leakage graphene nano-ribbon transistors (GNRFETs)-based static random access memory (SRAM) cell in 16nm technology that operates near the sub-threshold region in this study. In comparison to conventional Si-CMOS technology, the proposed cell improves read stability and writeability by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.67\mathbf {\times }$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.14\mathbf {\times }$ </tex-math></inline-formula> , respectively. The proposed cell considerably outperforms the existing 9T SRAMs cell in terms of power consumption, latency, read stability, and write-ability, according to the HSPICE simulation. In addition, at the low supply voltage of 325mV, the multi-threshold approach and transistor optimizations are used to improve the read static noise margin (RSNM). The proposed cell’s overall power consumption is lowered by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4161\mathbf {\times }$ </tex-math></inline-formula> when compared to a conventional 6T SRAM cell while using the multi-threshold approach in the write port. Device optimization and the multi-threshold approach, which enhances read and write performance, can considerably minimize read and write delays.

Low leakage, differential read scheme CNTFET based 9T SRAM cells for Low Power applications

ABSTRACT Electronic devices are persisting as the integral part in various medical devices. These devices require SRAMs (Static Random Access Memory) with power efficient capability to handle the data, as they occupy most of the die area. Especially, wearable devices are bringing new challenges in the design of an IC, where high stability and low static power dissipation are very much required. In this paper, two new Carbon Nanotube Field Effect Transistor (CNTFET) based 9T SRAM cell topologies are presented to improve the leakage power dissipation at standby mode while maintaining the stability of the cell. Differential bitlines with decoupled read port are used to assist the read disturbance and the subthreshold lowering as well as stack of transistors are employed to curtail the leakage power. The circuits are implemented at 900 mv in Cadence using CNTFET technology. The Architecture with a 4 × 4 array matrix of the proposed 9T cells is designed. These are found to be the better ones yielding good results compared to the existing designs.

Reliable and low power Negative Capacitance Junctionless FinFET based 6T SRAM cell

The increasing demand of portable gadgets for emerging VLSI applications call for the low power 6 T static random-access memory (SRAM) cell design. In this work, a 6 T SRAM cell has been designed using Negative Capacitance Junctionless FinFET (NC-JL FinFET) device. Further, the NC-JL FinFET based 6 T SRAM cell is evaluated for its power, stability and delay performance for read, write, and hold states and compared with conventional JL FinFET and published JL FinFET based SRAM. To investigate the reliability, the impact of ferroelectric thickness (TFE) and supply voltage (VDD) on the performance of NC-JL FinFET SRAM has also been investigated. It is shown that NC-JL FinFET SRAM dissipates 20% and ∼33% less static and dynamic power, with 1.2-, 1.5- and 1.18-times enhanced static noise margins in read, write, and hold state, respectively than JL FinFET SRAM. It also provides 37% and 20% faster read and write operations.

Reliability improved dual driven feedback 10T SRAM bit cell

This paper presents a dual driven feedback 10T (DDFB10T) static random-access memory (SRAM) bit cell with good read and write stability and that is free from half select issue. This DDFB10T cell working at VDD = 0.9 V achieves 1.5× higher static voltage noise margin (SVNM), and 0.48× lesser write trip voltage (WTV) than 6T SRAM cell. Monte Carlo simulation employing local and global variation using Cadence Virtuoso tool with 45 nm technology proves that the proposed bit cell is highly immune against process, voltage, and temperature (PVT) variations. The proposed DDFB10T bit cell exhibits lesser SVNM variability when it is normalized to that of 6T SRAM bit cell. The proposed DDFB10T cell is designed with the capability to provide a bit interleaved architecture for reducing half select issues.

Performance Analysis of 9T SRAM using 180nm, 90nm, 65nm, 32nm, 14nm CMOS Technologies

The growing markets for low-power electronic devices energized by battery have created the need for smaller power-efficient chips to prevent frequent charging of the source. Nowadays the market capitalization of low-power appliances is expected to grow from USD 4.9 billion by 2022 to USD 7.9 billion by 2027 as per global forecast to 2027 published by markets. The main factor leading to growth of low power electronics market includes demand of energy saving components, miniaturization, and entry of IoT (internet of things) devices. In addition, increased investment by automotive OEM (Original Equipment Manufacturer) and governments to promote the adoption of electric vehicles is expected to create more market opportunities. In this digital era, memory components play a major role in power consumption and this incites the research interest these days. CMOS (Complementary Metal Oxide Semiconductor) technology is growing rapidly towards greater integration into a single chip, resulting to a decrease in chip sizes using less space. Speed and stability demand is also growing up. Combined chip density increases as downtime technology continues. Stability and reliability are an important issue for the static random access memory (SRAM) memory device. In this paper, the design and analysis of CMOS based 9T SRAM cell in a variety of technologies is presented. The main focus of this review paper is to analyze 9T SRAM to test performance on several CMOS technologies (180nm, 90nm, 65nm, 45nm, 32nm, 14nm) with the help of a predictable technology (PTM) file. The butterfly curve method is used to examine the consistency of the SRAM bit cell in terms of static noise margin (SNM). It is clearly shown in this paper that as it progresses from 180nm to 14nm the delay decreases with stability.

A 7T SECURITY ORIENTED SRAM BITCELL USING VLSI

Power analysis (PA) attacks have become a serious threat to security systems by enabling secret data extraction through the analysis of the current consumed by the power supply of the system. Embedded memories, often implemented with six-transistor (6T) static random access memory (SRAM) cells, serve as a key component in many of these systems. However, conventional SRAM cells are prone to side-channel power analysis attacks due to the correlation between their current characteristics and written data. To provide resiliency to these types of attacks, we propose a security-oriented 7T SRAM cell, which incorporates an additional transistor to the original 6T SRAM implementation and a two-phase write operation, which significantly reduces the correlation between the stored data and the power consumption during write operations. The proposed 7T SRAM cell was implemented in a 28 nm technology and demonstrates over 1000× lower write energy standard deviation between write ‘1’ and ‘0’ operations compared to a conventional 6T SRAM. In addition, the proposed cell has a 39%–53% write energy reduction and a 19%–38% reduced write delay compared to other power analysis resistant SRAM cells. Key Words: Power Analysis, SRAM Design, 6T SRAM, 7T SRAM, Power Dissipation Software Tools:  Tanner eda Tool

Design of High Stability and Low Power 7T SRAM Cell in 32-NM CNTFET Technology

A novel 7T carbon nanotube field effect transistor (CNTFET)-based static random-access memory (SRAM) cell is proposed in this paper. Power and noise margin performances of the proposed SRAM cell is observed for write, hold and read operations. The power consumption and noise margin of the proposed SRAM cell is compared with the conventional 6T and 8T CNTFET-based SRAM cells. From the simulation, it is noted that the proposed 7T SRAM cell consumes lesser power and offers high static noise margin (SNM) compared to that of conventional 6T and 8T SRAM cells. The introduction of diode-based transistor structure improves the power and noise performance of the proposed SRAM cell. The effect of variation of parameters such as gate oxide thickness, dielectric constant, pitch, temperature, number of carbon nanotubes (CNT) and supply voltage on power and noise performance of proposed 7T SRAM cell is studied. Simulations were carried out with HSPICE simulation tool using Stanford University 32-nm CNTFET model.

Analyzing the Effect of Uncertainty in Low Power SRAM Cells Using Artificial Intelligence Technique

This paper addresses the uncertainty that is present in the design of static random access memory (SRAM) cells using an artificial intelligence (AI) technique. The SRAM has much uncertainty in high-performance portable very large-scale integration (VLSI) chips due to their performance and storage density. This paper presents the way for solving the uncertainty problem by evaluating point-by-point recreation derived for the memory cells inform of the power, speed, and area investment funds acquired in the advanced cell configuration when contrasted with the standard regular architecture for autonomous vehicles using AI algorithm. The adiabatic low power technique is implemented to enrich the configuration of the 6T-SRAM cells. The procedure of the adiabatic process will provide high loss in terms of dissipation of energy which is connected to ground (0V) and transition can be converted from ‘1’ to ‘0’. Moreover, this transition will be decreased to a high amount of degree within corresponding memory cells. Thus uncertainties with the AI model can able to deliver low power reduction using the automatic model of operation as standard adiabatic 6T SRAM cells are implemented. To prove the effectiveness in the reduction of uncertainties a low power margin is obtained with marginal values of 0.25 Volts which is much lesser than the existing models.

A Low-Power and High-Stability 8T SRAM Cell with Diode-Connected Transistors

This research paper proposes a low-power, high-stability 8T static random access memory (SRAM) cell. The proposed SRAM cell is a modified structure of the conventional 6T SRAM cell. The introduction of two diode-connected transistors in the pull-down network of the conventional 6T SRAM cell gives the proposed 8T SRAM cell structure. The presence of diode-connected transistors improves the power and noise performances of the proposed cell as compared to those of the conventional bit cells. The power consumption and static noise margin (SNM) of the suggested SRAM cell are calculated for write, hold and read operations. Also, the write and read delays of the proposed and conventional bit cells are observed. The power, speed, noise margin and area of the proposed 8T SRAM cell are compared with those of some of the existing SRAM cells. In comparison to conventional SRAM cells, the proposed cell consumes less power and has higher stability, according to the study. A novel dual-supply ([Formula: see text][Formula: see text]V and [Formula: see text][Formula: see text]V or 200[Formula: see text]mV) concept is applied for the existing and proposed SRAM cells. The noise and power performances of SRAM cells are well improved under the condition of dual supply as compared to the conventional supply voltage ([Formula: see text][Formula: see text]V and [Formula: see text][Formula: see text]V). A [Formula: see text] memory array of the proposed 8T SRAM cell is formed and the performance of the array structure is compared with that of [Formula: see text] array of the conventional 6T SRAM cell. The layouts of existing and proposed SRAM cells are illustrated. The simulation is carried out using the Cadence Virtuoso simulation EDA tool in 90-nm CMOS technology.

Node Voltage and KCL Model-Based Low Leakage Volatile and Non-Volatile 7T SRAM Cells

The current generation aims for Low power electronic gadgets like cell phones, PDAs, etc. This urged demand is met through adopting low power reduction techniques. These gadgets also demand the presence of cache memories, which are fabricated via Static Random Access Memory (SRAM) Cells. Now the challenge is in designing low leakage SRAM cells by adopting power reduction techniques. The proposed work of 7T based Volatile and Non-Volatile SRAM cell is carried through adopting efficient low power reduction technique referred to as Improved Self Controllable Voltage Level (I-SVL). Proposed 7T SRAM cell is based on Improved Self Controllable Voltage Level (I-SVL) technique which controls the supply voltage in Idle and Non Idle mode of SRAM cell. Also Upper-ISVL and Lower-ISVL supplies the Vdd and Vss as per the requirement there by controlling the leakage power. The proposed I-SVL based 7T Volatile and Non-Volatile is designed and simulated using Cadence Virtuoso spectre tool by using CMOS technology with gpdk 45nm. Proposed work carried is efficient in terms of sub threshold and total leakage currents in comparison with the earlier work. The obtained sub threshold and total leakage current of the proposed volatile 7T SRAM cell based on the I-SVL shows improvements in lower values with existing work by 15% and 32%. Also proposed Non-volatile based I-SVL 7T SRAM cell resulted in lesser sub threshold and total leakage current by an amount of 97% and 93% in comparison with the earlier work. The gate leakage current of proposed Non-volatile 7T SRAM cell resulted in 57% lower value in comparison with the earlier work.

Half‐selection disturbance free 8T low leakage SRAM cell

SummaryThis work presents a robust and low leakage new 8T static random access memory (SRAM) cell without any half‐selection disturbance. The proposed cell removes write disturbance by eliminating the trail from supply and ground. Furthermore, it removes the read disturbance by separating the read trail from the storage node. The proposed cell addresses the challenge of half select by using different control signals. The cell achieves low leakage because of virtual ground (VGND), series connected tail transistor, and access series stack transistors. To study the usefulness of the proposed SRAM, it is compared with 6T, 10T, 9T, PG9T, 7T, and 8T SRAM cells. The proposed SRAM minimizes leakage power, write power, and read power by 12.4%, 21.62%, and 29.06%. Furthermore, the proposed cell improves read and write noise margin by 57.19% and 19.96%, respectively, as compared to a conventional 6T SRAM. Again, the write energy consumption lowers to about 43.86× while read energy consumption 28.95× as compared to 10T SRAM.

Design of Low Power Transmission Gate Based 9T SRAM Cell

Considerable research has considered the design of low-power and high-speed devices. Designing integrated circuits with low-power consumption is an important issue due to the rapid growth of high-speed devices. Embedded static random-access memory (SRAM) units are necessary components in fast mobile computing. Traditional SRAM cells are more energy-consuming and with lower performances. The major constraints in SRAM cells are their reliability and low power. The objectives of the proposed method are to provide a high read stability, low energy consumption, and better writing abilities. A transmission gate-based multi-threshold single-ended Schmitt trigger (ST) 9T SRAM cell in a bit-interleaving structure without a write-back scheme is proposed. Herein, an ST inverter with a single bit-line design is used to attain the high read stability. A negative assist technique is applied to alter the trip voltage of the single-ended ST inverter. The multi-threshold complementary metal oxide semiconductor (MTCMOS) technique is adopted to reduce the leakage power in the proposed single-ended TG-ST 9T SRAM cell. The proposed system uses a combination of standard and ST inverters, which results in a large read stability. Compared with the previous ST 9T, ST 11T, 11T, 10T, and 7T SRAM cells, the proposed cell is implemented in Cadence Virtuoso ADE with 45-nm CMOS technology and consumes 35.80%, 42.09%, 31.60%, 12.54%, and 31.60% less energy for read operations and 73.59%, 93.95%, 92.76%, 89.23%, and 85.78% less energy for write operations, respectively.

Design of Area Efficient, Low-Power and Reliable Transmission Gate-based 10T SRAM Cell for Biomedical Application

There is an immense necessity of several kilo bytes of embedded memory for Biomedical systems which typically operate in the sub-threshold domain with perfect efficiency. SRAMs (Static Random Access Memory) dominates the total power consumption and the overall silicon area, as 70% of the die has been occupied by them. This brief proposes the design of a Transmission gate-based SRAM cell for Bio medical application eliminating the use of peripheral circuitry during the read operation. It commences the read operation directly with the help of Transmission gates with which the data stored in the storage nodes can be read, instead of using the precharge and sense amplifier circuits which suits better for the implantable devices. This topology offers smaller area, reduced delay, low power consumption as well as improved data stabilization in the read operation. The cell is implemented in 45nm CMOS technology operated at 0.45V.

Series diode‐connected current mirror based linear and sensitive negative bias temperature instability monitoring circuit

AbstractScaling of technology has a severe impact on the reliability of semiconductor devices. Negative bias temperature instability (NBTI) is a dominant factor in reliability degradation in nano‐scale technology. It is an aging phenomenon, which degrades the p‐channel metal oxide semiconductor (PMOS) transistors over time. A large area of the system on chip is covered by static random access memory (SRAM) and thus the overall system performance greatly depends on the stability of SRAM. In this paper, we evaluate the effect of NBTI on 6T SRAM cell performance for the stress period of 10 years. The simulation results show that the write margin is increased by 3.356% whereas hold static noise margin (SNM), read SNM, and standby leakage current is reduced by 6.53%, 23.86%, and 13.42%, respectively. We also present a series diode‐connected current mirror‐based linear and sensitive NBTI monitoring circuit using n‐channel metal oxide semiconductor (NMOS) transistors only. Continuous monitoring of the NBTI effect without any bias generator or control circuit is vital for the proposed sensor circuit. We have developed the electrical equivalent model and mathematical model of the proposed sensor for the fair comparison of results obtained through simulation and modeling. The sensitivity of the sensor is 40.6 μV/nA, and the sensor output voltage has a temperature variation of 20 μV/°C.

Cascade Current Mirror to Improve Linearity and Consistency in SRAM In-Memory Computing

Although multirow read is essential to achieve static random access memory (SRAM) in-memory computing (IMC), it may undermine circuit linearity and computational consistency across columns. In this study, we investigated the causes of nonlinearity and inconsistency. Based on detailed analyses, we proposed a cascade current mirror (CCM) peripheral circuit. Only four transistors were added to each bitline (BL) for voltage clamping and proportionally mirroring the read current. In addition, a 6T SRAM cell with double word lines operating with the CCM further reduced the delay and improved the computational consistency. We applied the structure to numerous prior studies and evaluated them using the 28-nm complementary metal-oxide semiconductor process. The measurement results show that the proposed CCM can reduce the integer nonlinearity by up to 70% at 0.8-V supply, and the computational consistency is substantially improved by 56.84% at 0.9-V supply. In addition, we verified the performance improvement through classification using a convolutional neural network, achieving 91% accuracy in the MNIST and 86% accuracy in the CIFAR-10. The area overhead was 1.77% in a 512×512 SRAM array when integrating the proposed CCM circuit.

Dependence of Temperature and Back-Gate Bias on Single-Event Upset Induced by Heavy Ion in 0.2-μm DSOI CMOS Technology

The dependence of temperature and back-gate bias on single-event upset (SEU) sensitivity is investigated based on a 0.2-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> double silicon-on-insulator (DSOI) technology. At room temperature, an obvious decrease in SEU cross section with the negative back-gate bias is experimentally observed for a DSOI static random access memory (SRAM). The physical mechanism of single-event effect (SEE) is explained through technology computer-aided design (TCAD) simulations. TCAD simulations were also performed to explain the impact of back-gate bias on charge collection and full width at half maximum (FWHM) of the pulsewidth at various temperatures. Both charge collection and FWHM of the pulsewidth increase significantly with temperature rising from 240 to 400 K. It is demonstrated that the SEU threshold linear energy transfer (LET) for a DSOI 6T SRAM cell decreases with an increase in temperature. Compared with a fully depleted SOI (FDSOI) technology, the unique independent back-gate bias scheme for a DSOI SRAM cell exhibits higher tolerance to SEU. At 400 K, it is found that the SEU threshold LET (LET_th) for a DSOI 6T SRAM cell increases by 12.5&#x0025; with back-gate bias of nMOS reduced from 0 to &#x2212;15 V.

Half-Select Disturb-Free 10T Tunnel FET SRAM Cell With Improved Noise Margin and Low Power Consumption

Tunnel field-effect transistors (TFETs) have become a potential candidate for replacing traditional MOSFETs in ultralow-power applications, in future. However, the forward p-i-n current of the TFET can seriously deteriorate the performance of the static random-access memory (SRAM) circuit. This brief proposes a half-select disturb-free 10T TFET SRAM cell with cascode isolation transistors. The proposed 10T SRAM cell can avoid the forward p-i-n current, drastically decreasing its leakage power consumption. At a supply voltage of 0.6 V, the leakage power consumption of the proposed 10T TFET SRAM cell is approximately four orders of magnitude lower than those of the outward-facing access transistor 6T (O_6T)/7T and the Schmitt–Trigger 10T (ST_10T) SRAM cells; the write power consumption is approximately 97% and 98% lower than those of the O_6T/7T/ST_10T and the combinational access 10T (CA_10T) SRAM cells, respectively. Moreover, the 10T SRAM cell exhibits 20% and 57% higher read static noise margin(RSNM) than those of the O_6T/7T and ST_10T cells, 115% and 411% higher write static noise margin(WSNM) than those of O_6T/7T and CA_10T, respectively, 20% higher hold static noise(HSNM) than those of O_6T/7T/ST_10T cells, and 89.8% lesser write delay than that of CA_10T at VDD = 0.6V, indicating that the proposed 10T SRAM cell has great potential for ultra-low power applications.

Design and Analysis of SRAM Cell using Negative Bit-Line Write Assist Technique and Separate Read Port for High-Speed Applications

The present day electronic gadgets have semiconductor memory devices to store data. The static random access memory (SRAM) is a volatile memory, often preferred over dynamic random access memory (DRAM) due to higher speed and lower power dissipation. However, at scaling down of technology node, the leakage current in SRAM often increases and degrades its performance. To address this, the voltage scaling is preferred which subsequently affects the stability and delay of SRAM. This paper therefore presents a negative bit-line (NBL) write assist circuit which is used for enhancing the write ability while a separate (isolated) read buffer circuit is used for improving the read stability. In addition to this, the proposed design uses a tail (stack) transistor to decrease the overall static power dissipation and also to maintain the hold stability. The comparison of the proposed design has been done with state-of-the-art work in terms of write static noise margin (WSNM), write delay, read static noise margin (RSNM) and other parameters. It has been observed that there is an improvement of 48%, 11%, 19% and 32.4% in WSNM while reduction of 33%, 39%, 48% and 22% in write delay as compared to the conventional 6T SRAM cell, NBL, [Formula: see text] collapse and 9T UV SRAM, respectively.

Design and mathematical analysis of a 7T SRAM cell with enhanced read SNM using PMOS as an access transistor

PurposeThis work is proposed for low power energy-efficient applications like laptops, mobile phones, and palmtops. In this study, P-channel metal–oxide–semiconductor (PMOS)’s are used as access transistor in 7 transistors (7 T) Static Random Access Memory (SRAM) cell, and the theoretical Static Noise Margin (SNM) analysis for the proposed cell is also performed. A cell is designed using 7 T which consists of 4 PMOS and 3 NMOS. In this paper write and hold SNM is addressed and read SNM is also calculated for the proposed 7 T SRAM cell.Design/methodology/approachThe authors have replaced N-channel metal–oxide–semiconductor (NMOS) access transistors with the PMOS access transistors, which results in proper data line recovery and provides the desired coupling. An error is likely to occur, if the read operation is performed too often probably by using the NMOS pass gate. It results in an improper recovery of the data line. Instead, by using PMOS as a pass gate, the time required for read operation can be brought down. As we know the mobility (µ) of the PMOS transistor is low, so the authors have used this property into the proposed design. When a low signal is applied to its control gate, the PMOS transistor come up with the desired coupling, when working as a pass gate.FindingsFeedback switched transistor is used in the proposed circuit, which plays an important role in the write operation. This transistor is in OFF state and PMOS’s work as access transistor, when the proposed cell operating in read mode. This helps in the reduction of power. This work is simulated using UMC 40 nm technology node in the cadence virtuoso environment. The simulated result shows that, write power saving of 51.54% and 61.17%, hold power saving of 25.68% and 48.93% when compared with reported 7 T and 6 T, respectively.Originality/valueThe proposed 7 T SRAM cell provides proper data line recovery at a lower voltage when PMOS works as the access transistor. Power consumption is very less in this technique and it is best suitable for low power applications.