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1 – 10 of 585Alok Kumar Mishra, Vaithiyanathan D., Yogesh Pal and Baljit Kaur
This 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…
Abstract
Purpose
This 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/approach
The 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.
Findings
Feedback 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/value
The 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.
Details
Keywords
Major area of a die is consumed in memory components. Almost 60-70% of chip area is being consumed by “Memory Circuits”. The dominant memory in this market is SRAM, even though…
Abstract
Purpose
Major area of a die is consumed in memory components. Almost 60-70% of chip area is being consumed by “Memory Circuits”. The dominant memory in this market is SRAM, even though the SRAM size is larger than embedded DRAM, as SRAM does not have yield issues and the cost is not high as compared to DRAM. At the same time, the other attractive feature for the SRAM is speed, and it can be used for low power applications. CMOS SRAM is the crucial component in microprocessor chips and applications, and as the said major portion of the area is dedicated to SRAM arrays, CMOS SRAM is considered to be the stack holders in the memory market. Because of the scaling feature of CMOS, SRAM had its hold in the market over the past few decades. In recent years, the limitations of the CMOS scaling have raised so many issues like short channel effects, threshold voltage variations. The increased thrust for alternative devices leads to FinFET. FinFET is emerging as one of the suitable alternatives for CMOS and in the region of memory circuits.
Design/methodology/approach
In this paper, a new 11 T SRAM cell using FinFET technology has been proposed, the basic component of the cell is the 6 T SRAM cell with 4 NMOS access transistors to improve the stability and also makes it a dual port memory cell. The proposed cell uses a header scheme in which one extra PMOS transistor is used which is biased at different voltages to improve the read and write stability thus, helps in reducing the leakage power and active power.
Findings
The cell shows improvement in RSNM (read static noise margin) with LP8T by 2.39× at sub-threshold voltage 2.68× with D6T SRAM cell, 5.5× with TG8T. The WSNM (write static noise margin) and HM (hold margin) of the SRAM cell at 0.9 V is 306 mV and 384 mV. It shows improvement at sub-threshold operation also. The leakage power is reduced by 0.125× with LP8T, 0.022× with D6T SRAM cell, TG8T and SE8T. The impact of process variation on cell stability is also discussed.
Research limitations/implications
The FinFet has been used in place of CMOS even though the FinFet has been not been a matured technology; therefore, pdk files have been used.
Practical implications
SRAM cell has been designed which has good stability and reduced leakage by which we can make an array and which can be used as SRAM array.
Social implications
The cell can be used for SRAM memory for low power consumptions.
Originality/value
The work has been done by implementing various leakage techniques to design a stable and improved SRAM cell. The advantage of this work is that the cell has been working for low voltage without degrading the stability factor.
Details
Keywords
Mitesh Jethabhai Limachia, Rajesh A. Thakker and Nikhil J. Kothari
This paper aims to propose a new ten-transistor (10T) SRAM bit-cell with differential read and write operations. The cell structure has read buffer on each side of the cell to…
Abstract
Purpose
This paper aims to propose a new ten-transistor (10T) SRAM bit-cell with differential read and write operations. The cell structure has read buffer on each side of the cell to improve read performance and comprises six main body transistors’ connections similar to the commercial 6T SRAM cell to improve write performance. The proposed bit-cell is designed with tri-gated FinFET technology and implemented on a silicon-on-insulator (SOI) substrate. 3D TCAD simulations are performed to characterize the efficacy of the proposed bit-cell. Performance characteristics of the proposed bit-cell are compared with the recently reported 8T bit-cell as well as the commercial 6T cell. The proposed bit-cell achieves 26.50 per cent and 35.10 per cent higher read static noise margin (RSNM) as compared with that of 8T and 6T bit-cells, respectively, at a VDD of 0.9 V. The proposed bit-cell also offers 54.78 per cent and 21.18 per cent smaller read delay compared with 8T SRAM-NEW and 6T bit-cells, respectively. The static power dissipation of the proposed bit-cell is comparable with that of the 6T bit-cell and 24.5 per cent lesser compared with that of the 8T bit- cell. The overall electrical quality of the SRAM circuit with the proposed bit-cell is enhanced up to 1.673 times and 1.22 times as compared with the 8T SRAM-NEW and 6T bit-cells, respectively.
Design/methodology/approach
A new 10T SRAM bit-cell with differential read and write operations is proposed. The proposed bit-cell is designed with tri-gated FinFET technology and implemented on an SOI substrate. 3D TCAD simulations are performed to characterize the efficacy of the proposed bit-cell. Performance characteristics of the proposed bit-cell are compared with the recently reported 8T bit-cell as well as the commercial 6T cell.
Findings
The proposed bit-cell achieves 26.50 per cent and 35.10 per cent higher RSNM as compared with that of the 8T and 6T bit-cells, respectively, at a VDD of 0.9V. The proposed bit-cell also offers 54.78 per cent and 21.18 per cent smaller read delay compared with the 8T SRAM-NEW and 6T bit-cells, respectively. The static power dissipation of the proposed bit-cell is comparable with that of the 6T bit-cell and 24.5 per cent lesser compared with that of the 8T bit-cell.
Originality/value
The proposed bit-cell is novel compared with existing bit-cells.
Details
Keywords
Kumar Neeraj and Jitendra Kumar Das
High throughput and power efficient computing devices are highly essential in many autonomous system-based applications. Since the computational power keeps on increasing in…
Abstract
Purpose
High throughput and power efficient computing devices are highly essential in many autonomous system-based applications. Since the computational power keeps on increasing in recent years, it is necessary to develop energy efficient static RAM (SRAM) memories with high speed. Nowadays, Static Random-Access Memory cells are predominantly liable to soft errors due to the serious charge which is crucial to trouble a cell because of fewer noise margins, short supply voltages and lesser node capacitances.
Design/methodology/approach
Power efficient SRAM design is a major task for improving computing abilities of autonomous systems. In this research, instability is considered as a major issue present in the design of SRAM. Therefore, to eliminate soft errors and balance leakage instability problems, a signal noise margin (SNM) through the level shifter circuit is proposed.
Findings
Bias Temperature Instabilities (BTI) are considered as the primary technology for recently combined devices to reduce degradation. The proposed level shifter-based 6T SRAM achieves better results in terms of delay, power and SNM when compared with existing 6T devices and this 6T SRAM-BTI with 7 nm technology is also applicable for low power portable healthcare applications. In biomedical applications, Body Area Networks (BANs) require the power-efficient SRAM design to extend the battery life of BAN sensor nodes.
Originality/value
The proposed method focuses on high speed and power efficient SRAM design for smart ubiquitous sensors. The effect of BTI is almost eliminated in the proposed design.
Details
Keywords
Kumar Neeraj, Mohammed Mahaboob Basha and Srinivasulu Gundala
Smart ubiquitous sensors have been deployed in wireless body area networks to improve digital health-care services. As the requirement for computing power has drastically…
Abstract
Purpose
Smart ubiquitous sensors have been deployed in wireless body area networks to improve digital health-care services. As the requirement for computing power has drastically increased in recent years, the design of low power static RAM-based ubiquitous sensors is highly required for wireless body area networks. However, SRAM cells are increasingly susceptible to soft errors due to short supply voltage. The main purpose of this paper is to design a low power SRAM- based ubiquitous sensor for healthcare applications.
Design/methodology/approach
In this work, bias temperature instabilities are identified as significant issues in SRAM design. A level shifter circuit is proposed to get rid of soft errors and bias temperature instability problems.
Findings
Bias Temperature Instabilities are focused on in recent SRAM design for minimizing degradation. When compared to the existing SRAM design, the proposed FinFET-based SRAM obtains better results in terms of latency, power and static noise margin. Body area networks in biomedical applications demand low power ubiquitous sensors to improve battery life. The proposed low power SRAM-based ubiquitous sensors are found to be suitable for portable health-care devices.
Originality/value
In wireless body area networks, the design of low power SRAM-based ubiquitous sensors are highly essential. This design is power efficient and it overcomes the effect of bias temperature instability.
Details
Keywords
Pramod Kumar Patel, M.M. Malik and Tarun Kumar Gutpa
The performance of the conventional 6T SRAM cell can be improved by using GNRFET devices with multi-threshold technology. The proposed cell shows the strong capability to operate…
Abstract
Purpose
The performance of the conventional 6T SRAM cell can be improved by using GNRFET devices with multi-threshold technology. The proposed cell shows the strong capability to operate at the minimum supply voltage of 325 mV, whereas the conventional Si-CMOS 6 T SRAM unable to operate below 725 mV, which result in an acceptable failure rate.The advance of Si-CMOS (complementary metal-oxide-semiconductor) based 6 T SRAM cell faces inherent limitation with aggressive downscaling. Hence, there is a need to propose alternatives for the conventional cells.
Design/methodology/approach
This study aims to improve the performance of the conventional 6T SRAM cell using dual threshold technology, device sizing, optimization of supply voltage under process variation with GNRFET technology. Further performance can be enhanced by resolving half-select issue.
Findings
The GNRFET-based 6T SRAM cell demonstrates that it is capable of continued improve the performance under the process, voltage, and temperature (PVT) variations significantly better than its CMOS counterpart.
Research limitations/implications
Nano-material fabrication technology of GNRFETs is in the early stage; hence, the different transistor models can be used to evaluate the parameters of future GNRFETs circuit.
Practical implications
GNRFET devices are suitable for implementing low power and high density SRAM cell.
Social implications
The conventional Si-CMOS 6 T SRAM cell is a core component and used as the mass storage element in cache memory in computer system organization, mobile phone and other data storage devices.
Originality/value
This paper presents a new approach to implement an alternative design of GNRFET -based 6T SRAM cell with doped reservoirs that also supports process variation. In addition, multi-threshold technology optimizes the performance of the proposed cell. The proposed design provides a means to analyze delay and power of GNRFET-based SRAM under process variation with considering edge roughness, and offers design and fabrication insights for cell in the future.
Details
Keywords
C.M.R. Prabhu and Ajay Kumar Singh
Low power static‐random access memories (SRAM) has become a critical component in modern VLSI systems. In cells, the bit‐lines are the most power consuming components because of…
Abstract
Purpose
Low power static‐random access memories (SRAM) has become a critical component in modern VLSI systems. In cells, the bit‐lines are the most power consuming components because of larger power dissipation in driving long bit‐line with large capacitance. The cache write consumes considerable large power due to full voltage swing on the bit‐line. The aim of the paper is to propose a new SRAM cell architecture to reduce the power consumption during write 0 and write 1 operation.
Design/methodology/approach
The proposed circuit includes two tail transistors in the pull‐down path of inv‐A and inv‐B. The simulated results of the proposed cell is compared with Conventional 6T SRAM cell and zero‐asymmetric SRAM cell.
Findings
The proposed SRAM cell consumes less power than the conventional SRAM cell during write operation. The write access delay is reported to be lower than conventional and ZA SRAMs in the proposed circuit. The read operation is similar to Conventional SRAM cell but due to tail transistors the read access delay and stability is poor in the present circuit which can be improved by careful transistors sizing.
Originality/value
The paper proposes a SRAM cell to reduce the power in write “0” as well as write “1”operation by introducing two tail transistors.
Details
Keywords
Vaclav Snasel, Tran Khanh Dang, Josef Kueng and Lingping Kong
This paper aims to review in-memory computing (IMC) for machine learning (ML) applications from history, architectures and options aspects. In this review, the authors investigate…
Abstract
Purpose
This paper aims to review in-memory computing (IMC) for machine learning (ML) applications from history, architectures and options aspects. In this review, the authors investigate different architectural aspects and collect and provide our comparative evaluations.
Design/methodology/approach
Collecting over 40 IMC papers related to hardware design and optimization techniques of recent years, then classify them into three optimization option categories: optimization through graphic processing unit (GPU), optimization through reduced precision and optimization through hardware accelerator. Then, the authors brief those techniques in aspects such as what kind of data set it applied, how it is designed and what is the contribution of this design.
Findings
ML algorithms are potent tools accommodated on IMC architecture. Although general-purpose hardware (central processing units and GPUs) can supply explicit solutions, their energy efficiencies have limitations because of their excessive flexibility support. On the other hand, hardware accelerators (field programmable gate arrays and application-specific integrated circuits) win on the energy efficiency aspect, but individual accelerator often adapts exclusively to ax single ML approach (family). From a long hardware evolution perspective, hardware/software collaboration heterogeneity design from hybrid platforms is an option for the researcher.
Originality/value
IMC’s optimization enables high-speed processing, increases performance and analyzes massive volumes of data in real-time. This work reviews IMC and its evolution. Then, the authors categorize three optimization paths for the IMC architecture to improve performance metrics.
Details
Keywords
Computers need clean, reliable, electrical power. The various faults of electrical power, such as spikes, sags, outages, noise, frequency variations, and static electricity, are…
Abstract
Computers need clean, reliable, electrical power. The various faults of electrical power, such as spikes, sags, outages, noise, frequency variations, and static electricity, are defined and described. Preventive measures that computer users can employ to reduce the potential of electrical problems are discussed, as are the processes for detecting, diagnosing, and curing electrical problems when they do occur. Sidebars consider: transformers; power distribution units (PDUs); surge currents/ linear and non‐linear loads; and sizing the power conditioning system. The next issue will conclude this series with an article on uninterruptible power supplies and a bibliography.
Sandeep Garg and Tarun Kumar Gupta
This paper aims to propose a new fin field-effect transistor (FinFET)-based domino technique low-power series connected foot-driven transistors logic in 32 nm technology and…
Abstract
Purpose
This paper aims to propose a new fin field-effect transistor (FinFET)-based domino technique low-power series connected foot-driven transistors logic in 32 nm technology and examine its performance parameters by performing transient analysis.
Design/methodology/approach
In the proposed technique, the leakage current is reduced at footer node by a division of current to improve the performance of the circuit in terms of average power consumption, propagation delay and noise margin. Simulation of existing and proposed techniques are carried out in FinFET and complementary metal-oxide semiconductor technology at FinFET 32 nm technology for 2-, 4-, 8- and 16-input domino OR gates on a supply voltage of 0.9 V using HSPICE.
Findings
The proposed technique shows maximum power reduction of 77.74% in FinFET short gate (SG) mode in comparison with current-mirror-based process variation tolerant (CPVT) technique and maximum delay reduction of 51.34% in low power (LP) mode in comparison with CPVT technique at a frequency of 100 MHz. The unity noise gain of the proposed circuit is 1.10× to 1.54× higher in comparison with different existing techniques in FinFET SG mode and 1.11× to 1.71× higher in FinFET LP mode. The figure of merit of the proposed circuit is up to 15.77× higher in comparison with existing domino techniques.
Originality/value
The research proposes a new FinFET-based domino technique and shows improvement in power, delay, area and noise performance. The proposed design can be used for implementing high-speed digital circuits such as microprocessors and memories.