Low Power VLSI Design Techniques: A Review

Since CMOS technology consumes less power it is a key technology for VLSI circuit design. With technologies reaching the scale of 10 nm, static and dynamic power dissipation in CMOS VLSI circuits are major issues. Dynamic power dissipation is increased due to requirement of high speed and static power dissipation is at much higher side now a days even compared to dynamic power dissipation due to very high gate leakage current and subthreshold leakage. Low power consumption is equally important as speed in many applications since it leads to a reduction in the package cost and extended battery life. This paper surveys contemporary optimization techniques that aims low power dissipation in VLSI circuits.

Novel Global Interconnect structure with improved Elmore Delay Estimation for Low-Power Applications

With advancements in technology, size and speed have been the important facet in VLSI interconnects. Interconnects are known as the basic building block that provide a connection between two or more blocks and have scaling problems that an IC designer faces while designing. As scaling increases, the impact of interconnect in the VLSI circuits became even more important. It controls all the important electrical characteristics on the chip. With scale-down technology, interconnects not only become closer with each other but their dimensions also change which can directly impact the circuit parameters. Certain RC structures have already been defined to control these parameters but in this paper, authors have proposed a new interconnect structure with improved Elmore delay estimation to reduce delay and power consumption in lumped and distributed interconnect circuits using Pulse and Ramp inputs. Further, the proposed model is estimated and verified theoretically. The linear relationship of power consumption and delay for the RC structure has been observed. The proposed structure with improved Elmore delay estimation shows improvement in delay by 64.25% in lumped circuits and 68.75% in distributed circuits in comparison to existing Elmore delay calculations which help in increasing the overall speed of the interconnect circuit.

Analysis On Power Gating Circuits Based Low Power VLSI Circuits (BCD Adder)

Currently, energy consumption in the digital circuit is a key design parameter for emerging mobile products. The principal cause of the power dissipation during idle mode is leakage currents, which are rising dramatically. Sub-threshold leakage is increased by the scaling of threshold voltage when gate current leakage increases because oxide thickness is scaled. With rising demands for mobile devices, leakage energy consumption has received even greater attention. Since a mobile device spends most of its time in standby mode, leakage power savings need to prolong the battery life. That is why low power has become a significant factor in CMOS circuit design. The required design and simulation of an AND gate with the BSIM4 MOS parameter model at 27 0C, supply voltage of 0,70V with CMOS technology of 65nm are the validation of the suitability of the proposed circuit technology. AND simulation. The performance parameters for the two AND input gate are compared with the current MTCMOS and SCCMOS techniques, such as sub-threshold leakage power dissipations in active and standby modes, the dynamic dissipation, and propagation period. The proposed hybrid super cutoff complete stack technique compared to the current MTCMOS technology shows a reduction in sub-threshold dissipation power dissipation by 3. 50x and 1.15x in standby modes and active modes respectively. The hybrid surface-cutting technique also shows savings of 2,50 and 1,04 in power dissipation at the sub-threshold in standby modes and active modes compared with the existing SCCMOS Technique.

IMPLEMENTATION OF ELECTRONIC DEVICES OF CMOS FULL ADDER IN LOW POWER VLSI CIRCUITS

Battery-powered devices (for example, mobile phones, digital personal aids, etc) are increasing on the mobile electronic systems market by developing microelectronic circuits with low energy dissipation. The problem of dissipating power could limit the flexibility of the computer system, as the chip’s density and complexity keep on increasing. The power supply consumes approximately 35% of the chip power, particularly at the nanometer level. The purpose of this project is to investigate the efficiency of one of the most reliable low power concepts called Power Gating. It is only nanometer-scale CMOS devices that are the most common technology in existing VLSI systems. Leakage power has become an integral component of total power in the nanometer technology regime. The ALU’s basic feature unit is Full Adder. The electricity consumption of an ALU is decreased by decreasing the energy consumption of an ALU, and an ALU will reduce the power consumption by decreasing the total power consumption. So these days, the complete adder designs are becoming more common with low power characteristics. The proposed project shows the concept of the micro wind tool for low power less transistors.

Design of low-power CMOS VLSI circuits using multi-objective optimization in genetic algorithms

This paper presents a design CAD tool for automated design of digital CMOS VLSI circuits. In order to fit the circuit performance into desired specifications, a multi-objective optimization approach based on genetic algorithms (GA) is proposed and the transistor sizes are calculated based on the analytical equations describing the behavior of the circuit. The optimization algorithm is developed in MATLAB and the performance of the designed circuit is verified using HSPICE simulations based on 0.18µm CMOS technology parameters. Different digital integrated circuits were successfully designed and verified using the proposed design tool. It is also shown in this paper that, the design results obtained from the proposed algorithm in MATLAB, have a very good agreement with the obtained circuit simulation results in HSPICE.

Low power and area efficient design of fir filter using enhanced clock gating technique

The main aim of this approach is to improve the design model of filters for optimal circuit design. The objective of this proposed method is to improve the performance of VLSI circuit like area, power, and delay. In recent days, the filters are most applicable designs in DSP, medical diagnosis and arithmetic computations. In Digital Signal Processing and communication applications, the FIR filter plays an important role. The Finite Impulse Response is designed with number of adders, multipliers, subtraction units, transfer functions and delay elements. The VLSI circuits are applied in various applications, but the number adders and multipliers occupy the design space since it increases the area and delay factors. The main aim is to reduce the number of adders and multiplier by various computational algorithms. The existing research work uses carry save accumulator with ripple carry adder and binary multiplier. In proposed method, the enhanced Vedic multiplication logic and improved carry lookahead adder logic improves the result. In Vedic multiplication algorithm, the number of adder logic is minimized by adding speculative Brent-kung adder logic in it. The fastest adder in VLSI circuit is CLA (Carry look ahead adder logic), which is improved by utilizing the result of reduced power consumption and delay. In this proposed research work, the power optimization is done by using enhanced clock gating technique. Here, area, power, and delay factors are measured and it is compared with conventional FIR filter design. The proposed method improves the result in the way of area, power, and delay. The whole FIR filter structure is designed and power optimized by connecting with an enhanced clock gating technique. This proposed design and simulate by using Xilinx ISE 14.5 and it is synthesize by ModelSim.

Low Power, High Speed MUX Based Area Efficient Dadda Multiplier

The multiplier is a fundamental building block in most digital ICs’ arithmetic units. The multiplier architecture in modern VLSI circuits must meet the main parameters of low power, high speed, and small area requirements. In this paper, a 4-bit multiplier is constructed using the Dadda algorithm with enhanced Full and Half adder blocks to achieve a smaller size, lower power consumption, and minimum propagation delay. The Dadda Algorithm-designed multiplier is used in the first phase to reduce propagation delay while adding partial products in three stages provided by AND Gates. In the second phase, each stage of the Dadda tree algorithm is built with an enhanced Full and half adders to reduce the design area, propagation delay, and power consumption while still meeting the requirements of the current scenario by using MUX logic. In an average of Conventional array Multipliers, the proposed Dadda multiplier achieved an 84.68% reduction in delay, 70.89% reduction in power, 84.68% increase in Maximum Usable Frequency (MUF), and 95.55% reduction in Energy per Samples (EPS).

4-bit Carry Look Ahead Adder Using MGDI Technique

Today's high-performance processor is built with arithmetic logic units that add and subtract key components. Design considerations related to low power and high performance digital VLSI circuits have become more prevalent in today's world. In order to develop low-power and high-performance processors, the designers need to design their adder circuits with the required speed and power dissipation for their applications. This topic introduces the concept of a adder using MGDI Technique. The Exact Speculative Carry Look Ahead Adder the use of the Modified-GDI (Modified-Gate Diffusion Input) is cautioned in this work. The delay, location and energy trade off performs a integral role in VLSI. We already comprehend that designs which are of CMOS fashion occupy extra area might also eat extra strength consumption. The switching conduct of the circuit reason the heating up of integrated circuits affects the working stipulations of the purposeful unit. The adders are the most important parts of countless applications such as microprocessors, microcontrollers and digital signal processors and additionally in actual time applications. Hence it is necessary to minimize the adder blocks to format a perfect processor. This work is proposed on a 16 bit carry seem to be in advance adder is designed through using MGDI gate and 4T XOR gates and a speculator blocks. The proposed MGDI raise Look Ahead adder occupies 68% much less region and the strength consumption and the propagation extend additionally considerably reduces when in contrast to the traditional carry Look Ahead adder why because the variety transistors extensively reduces from 1448 (Conventional) to 456 (Proposed CLA). The simulation consequences of the proposed format carried out in Xilinx. Keywords: Delay, power dissipation, voltage, transistor sizing.