Variability aware FinFET SRAM cell with improved stability and power for low power applications

Circuit World ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 196-207
Author(s):  
Shilpi Birla
Keyword(s):  
Low Power ◽  
Threshold Voltage ◽  
Leakage Power ◽  
Static Noise Margin ◽  
Content Type ◽  
Noise Margin ◽  
Sram Cell ◽  
Memory Circuits ◽  
The Stability ◽  
Static Noise

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.

scholarly journals Restoration circuits for Low power Reduce Swing of 6T and 8T SRAM Cell With Improved Read and Write Margins

2021 ◽  
Vol 7 ◽  
pp. 22-34
Author(s):  
Vinod Kumar ◽  
Ram Murti Rawat
Keyword(s):  
Low Power ◽  
Static Noise Margin ◽  
Noise Margin ◽  
Equivalent Time ◽  
Sram Cell ◽  
Section Viii ◽  
Static Noise

A paper that examines the factors thataffect the Static Noise Margin (SNM) of a StaticRandom Access memories. At an equivalent time,they specialise in optimizing Read and Writeoperation of 8T SRAM cell which is best than 6TSRAM cell Using Swing Restoration Dual NodeVoltage. The read and Write operation and improveStability analysis. This SRAM technique on thecircuit or architecture level is required to improveread and write operation. during this paperComparative Analysis of 6T and 8T SRAM Cellswith Improved Read and Write Margin is completedfor 180 nm Technology with Cadence Virtuososchematics Tool.This Paper is organized as follows: thecharacteristics of 6T SRAM cell are described arerepresented in section VIII. In section IX, proposed8T SRAM cell is described. In section X, Standard8T SRAM cell is described. Section XI includes thesimulation results which give comparison of variousparameters of 6T and 8T SRAM cells. In Section XIISimulation Results and DC analysis and sectionXIII conclusion the work.

A 32 nm Read Disturb-free 11T SRAM Cell with Improved Write Ability

2019 ◽  
Vol 29 (05) ◽  
pp. 2050067
Author(s):  
S. R. Mansore ◽  
R. S. Gamad ◽  
D. K. Mishra
Keyword(s):  
High Performance ◽  
Model Simulation ◽  
Random Access ◽  
Leakage Power ◽  
Access Memory ◽  
Static Noise Margin ◽  
Noise Margin ◽  
Sram Cell ◽  
Operation Characteristics ◽  
Static Noise

Data stability, write ability and leakage power are major concerns in submicron static random access memory (SRAM) cell design. This paper presents an 11T SRAM cell with differential write and single-ended read. Proposed cell offers improved write ability by interrupting its ground connection during write operation. Separate read buffer provides disturb-free read operation. Characteristics are obtained from HSPICE simulation using 32[Formula: see text]nm high-performance predictive technology model. Simulation results show that the proposed cell achieves 4.5[Formula: see text] and 1.06[Formula: see text] higher read static noise margin (RSNM) as compared to conventional 6T (C6T) and PNN-based 10T cells, respectively, at 0.4[Formula: see text]V. Write static noise margin (WSNM) of the proposed design is 1.65[Formula: see text], 1.71[Formula: see text] and 1.77[Formula: see text] larger as compared to those of C6T, PPN-based 10T and PNN-based 10T cells, respectively, at 0.4V. Write “1” delay of the proposed cell is 0.108[Formula: see text] and 0.81[Formula: see text] as those of PPN10T and PNN10T cells, respectively. Proposed circuit consumes 1.40[Formula: see text] lesser read power as compared to PPN10T cell at 0.4[Formula: see text]V. Leakage power of the proposed cell is 0.35[Formula: see text] of C6T cell at 0.4[Formula: see text]V. Proposed 11T cell occupies 1.65[Formula: see text] larger area as compared to that of conventional 6T.

scholarly journals FinFET SRAM cell with improved stability and power for low power applications.

2019 ◽  
Vol 14 (2) ◽  
pp. 1-8
Author(s):  
Shilpi Birla
Keyword(s):  
Memory Cell ◽  
Static Noise Margin ◽  
Noise Margin ◽  
Sram Cell ◽  
Improved Stability ◽  
Cell Stability ◽  
Subthreshold Voltage ◽  
The Stability ◽  
Subthreshold Operation ◽  
Static Noise

In this paper, a new 11T SRAM cell using Double gate FET (FinFET technology) has been proposed, cell basic component is the 6T SRAM cell with 4 NMOS access transistors to improve the stability over CMOSFET circuits and also makes it a dual port memory cell. The proposed cell also used a header scheme in which one extra PMOS transistor is used which is biased at different voltages to improve the read and write stability which helps in reducing the leakage current, active power. The cell shows improvement in RSNM (Read Static Noise Margin) with LP8T by 2.39x at threshold and subthreshold voltage 2.68x with D6T SRAM cell, 5.5x with TG8T. The WSNM (Write Static Noise Margin) and HM (Hold Margin) of the SRAM cell at 0.9V is 306mV and 384mV.At subthreshold operation also, it shows improvement. The Leakage power reduced by 0.125x with LP8T, 0.022x with D6T SRAM cell, TG8T and SE8T. Impact of process variation on cell stability also been analyzed.

scholarly journals Ultra Low Power Process Tolerant 10T (PT10T) SRAM with Improved Read/Write Ability for Internet of Things (IoT) Applications

2017 ◽  
Author(s):  
Pooran Singh ◽  
Santosh Vishvakarma
Keyword(s):  
Internet Of Things ◽  
Power Consumption ◽  
Low Power ◽  
Leakage Power ◽  
Static Noise Margin ◽  
Ultra Low Power ◽  
Iot Applications ◽  
Noise Margin ◽  
Standby Mode ◽  
Static Noise

An ultra-low power (ULP), power gated static random access memory (SRAM) is presented for Internet of Things (IoT) applications, which operates in sub-threshold voltage ranges from 300mV to 500mV. The proposed SRAM has tendency to operate in low supply voltages with high static and dynamic noise margins. The IoT application involves battery enabled low leakage memory architecture in subthreshold regime which has low power consumption. Therefore, to improve power consumption along with better cell stability, a power gated 10T SRAM is presented. The proposed cell uses a power gated p-MOS transistor to reduce the leakage power or static power in standby mode. Moreover, due to the schmitt triggering and read decoupling of 10T SRAM the static and dynamic behavior in read, write and standby mode has shown enhanced tolerance at different process, voltage and temperature (PVT) conditions. The proposed SRAM shows better results in terms of leakage power, read static noise margin (RSNM), write static noise margin (WSNM), write-ability or write trip point (WTP), read-write energy and dynamic read margin (DRM). Further, these parameters are observed at 8-Kilo bit (Kb) and compared with already existing SRAM architectures. It is observed that the leakage power is reduced by 1/81×, 1/75× of the conventional 6T (C6T) SRAM and read decoupled 8T (RD8T) SRAM, respectively at 300mV VDD. On the contrary, RSNM, WSNM, WTP and DRM values are improved by 3×, 2×, 11.11% and 31.8% as compared to C6T SRAM, respectively. Similarly, proposed 10T has 1.48×, 25% and 9.75% better RSNM, WSNM and WTP values as compared to RD8T SRAM, respectively at 300mV VDD.

Effect of Threshold Roll-Off on Static Noise Margin of Sram Cell

2018 ◽  
Author(s):  
Sunil Kumar Ojha ◽  
O.P. Singh ◽  
G.R. Mishra ◽  
P.R. Vaya
Keyword(s):  
Circuit Design ◽  
Threshold Voltage ◽  
Channel Length ◽  
Small Scale ◽  
Static Noise Margin ◽  
Noise Margin ◽  
Sram Cell ◽  
Channel Reduction ◽  
On Chip ◽  
Static Noise

Thethreshold roll-off is a vital phenomena to be considered for any low-power and small-scale circuit design. With the advancement of the fabrication processes the channel length of the transistors is reducing rapidly, this reduction in the channel length affects the threshold voltage of the transistors very severely. To evaluate the effect of channel reduction on the threshold voltage this paper analyzes the threshold roll-off by taking SRAM cell into consideration. The reason behind choosing SRAM cell is that now the IC’s are fabricated using system on chip (SOC) design technique and currently approximately 70-80% of the SOC area are covered by memories only. One of the most important Figure of Merit for SRAM cell is its Static Noise Margin (SNM) and hence the effect of threshold-roll is implemented with respect to SNM of the SRAM cell.

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

2021 ◽  
pp. 2150270
Author(s):  
Jitendra Kumar Mishra ◽  
Lakshmi Likhitha Mankali ◽  
Kavindra Kandpal ◽  
Prasanna Kumar Misra ◽  
Manish Goswami
Keyword(s):  
Power Dissipation ◽  
High Speed ◽  
Random Access ◽  
Random Access Memory ◽  
Access Memory ◽  
Static Noise Margin ◽  
Semiconductor Memory ◽  
Noise Margin ◽  
Sram Cell ◽  
Static Noise

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.

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