Carry Lookahead Research Articles

Area-Delay-Power Efficient VLSI Architecture 2D FIR Filter using Modified Multipliers and Adders

In this paper, a low power, area, and delay 2D Finite Impulse Response (FIR) filter architecture is derived from an analysis of a memory-efficient design. The completely direct-form 2D FIR filter is where the idea of parallel processing is first presented. As a result, the FIR filter may make better use of its memory by reusing its contents. With a block size of L and a filter length of N, a non-separable 2D FIR filter structure is developed and implemented. The FIR filter's arithmetic module makes use of high-speed, low-power multipliers and Carry Look Ahead (CLA) adders, with the output calculated by a pipelined adder unit. Verilog HDL code is used to represent the proposed architecture, and the CADENCE environment's NC Simulator and RTL Compiler synthesis tool are used to verify the design. Existing memory-efficient 2D FIR filter hardware architectures are compared to the produced area, power, and delay reports. Using Modified CLA (MCLA) adders and pipelining, we were able to cut down on power consumption by 44% and delay by 20%. Index Terms: Memory reuse, 2D-FIR filter, Low Power Multiplier, Parallel Prefix Adder, Carry Look Ahead adder, and pipelining.

A novel energy efficient 4-bit vedic multiplier using modified GDI approach at 32 nm technology

Multipliers are essential components within digital signal processing, arithmetic operations, and various computational tasks, making their design and optimization crucial for improving the efficiency and performance of integrated circuits. Among multiplier architectures, Vedic multipliers stand out due to their inherent efficiency and speed, derived from ancient Indian mathematical principles. This study presents a comprehensive analysis and comparison of 4-bit Vedic multiplier designs utilizing Gate Diffusion Input (GDI), Complementary Metal-Oxide-Semiconductor (CMOS), and Transmission Gate (TG) technologies, utilizing different adder architectures such as Ripple Carry Adder (RCA), and Carry Lookahead Adder (CLA), Carry Skip Adder (CSA). The objective is to explore the performance, area, and power consumption characteristics of these multipliers across different technologies and adder implementations. Each multiplier architecture is meticulously designed and optimized to leverage the unique features of the respective technology while adhering to the principles of Vedic mathematics. The designs are evaluated based on parameters such as transistor count, delay, power dissipation, and area. The results demonstrate the effectiveness of GDI technology in terms of in tems of delay, area, power and PDP when compared with other technologies. The 4-bit Vedic multiplier has been designed using 32 nm technology within Tanner EDA software tools.

16-Bit Carry Look-Ahead Adder: Design and Layout with Cadence Tools Top of Form

Abstract: The development of highly organised architecture is the primary goal of the current communication world in order to achieve high speed computation with low power consumption. The Carry Look Ahead Adder is highly efficient due to its ability to reduce the propagation time of carry bits, resulting in time savings. The implementation of a 16-Bit Carry Look Ahead Adder using the Cadence tool is carried out in our project. Logical equations for carry generation (G) and carry propagation (P) are used to create the carry and sum for the 1-bit adder. Then, using the Virtuoso schematic editor, a single bit carry is developed. After that, a fresh cell view for the carry block is made and supplied as an input for adder implementations. Next, the bit rate is increased to 4 bits. Using this 4 bit adder, 8/16 bit adder is implemented using Cadence tool. It is necessary to have a basic understanding of IC design guidelines and fabrication procedures in order to produce the layout. Within the electronic VLSI design system, the layout will go through a Design Rule Check to find any breaches

Area and delay efficient RNS-based FIR filter design using fast multipliers

In today's digital age, speed, and area are the primary design concerns. Increasing the rate at which multiplication and addition are performed has always been a need for developing cutting-edge technologies. Wallace multipliers, and Dadda multipliers, are one of the fastest multipliers used in many processors to accomplish fast arithmetic operations. A novel approach to design a LookUp Table (LUT) multiplier was proposed and implemented in Finite Impulse Response (FIR) filter. To improve the Residue Number System (RNS) based FIR filter's performance, several adders like Carry Look ahead (CLA) adder, Kogge Stone adder (KSA) and proposed adder architectures have been implemented. When compared with the 16 tap with 32 bit proposed adder with LUT multiplier, the hardware resource utilization (Logic Elements) is decreased by 5.97 % and in 32 tap with 16 bit combination, it decreases by 7.60 %.When compared with 32 tap with 4 bit word length, the proposed adder with LUT multiplier in the highlighted combinations, the Fmax is increased by 19.28 % and in 32 tap with 16 bit, it increases by 29.74 %. The Low-pass RNS FIR filter is designed for a cut-off frequency of 50 Hz and generated filter coefficients in MATLAB and implemented to denoising the ECG signal.

Carry look-ahead and ripple carry method based 4-bit carry generator circuit for implementing wide-word length adder

In this study, an approach to implement wide word-length adders is presented by proposing a hybrid 4-bit carry generator. The proposed hybrid carry generator uses a combination of Carry Look-Ahead (CLA) and Ripple Carry (RC) styles. Utilization of RC style in the first 3-bits aims to reduce transistor count along with power consumption. On the other hand, the CLA method is used in the 4th bit to ensure speed. Also, the proposed CLA for the 4th bit uses a novel approach, which uses inverted Propagate (Pi‾) - Generate (Gi‾) circuits rather than using the conventional ones. Performance of the proposed hybrid RC-CLA based 4-bit carry generator is benchmarked against existing designs. Moreover, the designs (proposed and existing) are used to implement a 16-bit adder to check the effect of using the 4-bit unit cells in a wide word length structure. The proposed design outperforms the existing ones in Average Power and Power Delay Product (PDP). As a result, the design can bring drastic performance enhancement in modern low-power battery-operated devices to reduce power consumption.

Design of Modified Booth’s Encoder Using SPST technique

This paper presents the design and implementation of signed-unsigned Modified Booth Encoding (SUMBE) multiplier. The present Modified Booth Encoding (MBE) multiplier and the Baugh-Wooley multiplier perform multiplication operation on signed numbers only. Therefore, this paper presents the design and implementation of SUMBE multiplier. The modified Booth Encoder circuit generates half the partial products in parallel. By extending sign bit of the operands and generating an additional partial product the SUMBE multiplier is obtained. The Carry Save Adder (CSA) tree and the final Carry Look ahead (CLA) adder used to speed up the multiplier operation. Since signed and unsigned multiplication operation is performed by the same multiplier unit the required hardware and the chip area reduces and this in turn reduces power dissipation and cost of a system. The proposed radix-2 modified Booth algorithm MAC with SPST gives a factor of 5 less delay and 7% less power consumption as compared to array MAC.

Wide word‐length carry‐select adder design using ripple carry and carry look‐ahead method based hybrid 4‐bit carry generator

AbstractThis research aims to fill up the research gap in energy‐efficient transistor‐level wide word‐length carry circuit generator by using ripple carry (RC) and carry look‐ahead (CLA) method‐based hybrid 4‐bit carry generation process for wide word‐length carry‐select adder (CSLA). Compared to the existing 4‐bit CLA architectures, the proposed 4‐bit RC‐CLA method‐based hybrid 4‐bit carry generator showed performance improvement in terms of power and power delay product (PDP). Later, the 4‐bit carry architectures (existing and proposed) were used as a base to implement 16‐bit carry select adder (CSA) in order to investigate and compare the effect of using the proposed hybrid RC‐CLA based 4‐bit carry generator in large structures. Unlike 4‐bit operation, the proposed design displayed the best performance in power and PDP for 16‐bit CSA extension, which proves its effectiveness in wide word‐length adder structures.

Performance Measurement of Energy Efficient and Highly Scalable Hybrid Adder

The adders are the vital arithmetic operation for any arithmetic operations like multiplication, subtraction, and division. Binary number additions are performed by the digital circuit known as the adder. In VLSI (Very Large Scale Integration), the full adder is a basic component as it plays a major role in designing the integrated circuits applications. To minimize the power, various adder designs are implemented and each implemented designs undergo defined drawbacks. The designed adder requires high power when the driving capability is perfect and requires low power when the delay occurred is more. To overcome such issues and to obtain better performance, a novel parallel adder is proposed. The design of adder is initiated with 1 bit and has been extended up to 32 bits so as verify its scalability. This proposed novel parallel adder is attained from the carry look-ahead adder. The merits of this suggested adder are better speed, power consumption and delay, and the capability in driving. Thus designed adders are verified for different supply, delay, power, leakage and its performance is found to be superior to competitive Manchester Carry Chain Adder (MCCA), Carry Look Ahead Adder (CLAA), Carry Select Adder (CSLA), Carry Select Adder (CSA) and other adders.

VLSI implementation of Kogge-Stone Adder for low-power applications

The adder is a vital part of the Central Processing Unit (CPU) that can perform computational operations. It is used in digital components, mainly in the design of integrated circuits. Recent decades have seen a sharp rise in demand for mobile electronics, which has increased the need for highly efficient Very Large-Scale Integration (VLSI) structures. All operations must be computed using low-power, space-efficient designs that run faster. The Kogge-Stone adder (KSA) is an extension of the carry look-ahead adder which is used for performing fast addition in high-performance computing systems. This study compares the latency, space, and energy used by the Kogge-Stone Adder after development and implementation in Xilinx Vivado using Verilog to those of the Ripple Carry Adder (RCA) and Carry Lookahead Adder (CLA). The results show that the KSA has a decrease in power consumption as well as improvements in high speed and area compaction when compared to the RCA and CLA.

SYNTHESIS AND FPGA VALIDATION OF PARALLEL PREFIX ADDERS

In this work, the design implementation, functionality testing, design synthesis and bitstream generation of various n-bit adder architecture of RCA, CLA, CSkA and KSA. And addresses various forms of adders which include Ripple-carry (RCA), Carry-lookahead (CLA), Carry-skip (CSkA), and Kogge-stone (KSA) adders. Certain design restrictions for digital VLSI circuits, such speed and area, can be satisfied using these adders. All the mentioned adder are designed using Verilog HDL, implemented the same on Xilinx Vivado 2018.2, functionality test is carried out by writing testbench, bitstream generated for the same and synthesized using Cadence genus.

Design Optimization of the 64-Bit Carry Look-Ahead Adder Based on FPGA and Verilog HDL

Design Optimization of the 64-Bit Carry Look-Ahead Adder Based on FPGA and Verilog HDL

A New Low Power, Area Efficient 4-bit Carry Look Ahead Adder in CNFET Technology

In this paper, a new hybrid low-power and area efficient Carry Look-Ahead Adder in CNFET technology based on the full-swing Gate Diffusion Input (GDI) technique is proposed. The proposed CLA design in GDI logic style, not only decreases the circuit area effectively but also decreases the power consumption and delay parameters as well. The proposed design is simulated in HSPICE using the CNFET model parameters. Finally, the simulation results justify a good improvement in the circuit performance parameters such as power consumption, delay, chip size area and power-delay product (PDP) for the proposed CLA circuit.

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 VERY LARGE SCALE INTEGRATION (VLSI) DESIGN OF FINITE IMPULSE RESPONSE (FIR) FILTER FOR BIOMEDICAL IMAGING APPLICATION

Nowadays, the medical image processing techniques are using Very Large Scale Integrated (VLSI) designs for improving the availability and applicability. The digital filters are important module of Digital Signal Processing (DSP) based systems. Existing Finite Impulse Response (FIR) design approach performed with Partial Full Adder (PFA) based Carry Lookahead Adder (CLA) and parallel prefix adder logic in Vedic multiplier. Objective of this approach is to improve the performance of VLSI circuit by obtaining the result of area, power and delay, also, effective incorporation between VLSI circuit and image processing approach makes improved application availability. The design of high speed digital FIR filter is designed with various adders and multipliers. The incorporation of VLSI design and image processing techniques are used on biomedical imaging applications. The Enhanced FIR filter design utilized the hybrid adder and adaptive Vedic multiplier approaches for increasing the performance of VLSI part and the image processing results are taken from Matrix Laboratory tool. This proposed FIR filter design helps to perform the biomedical imaging techniques. The simulation result obtains the performance of enhanced FIR with area, delay and power; for biomedical imaging, Mean Square Error (MSE) and Peak Signal to Noise Ratio (PSNR) is obtained. Comparing with existing and proposed method, the proposed FIR filter for biomedical imaging application obtains the better result. Thus the design model states with various application availability of VLSI image processing approaches and it obtains the better performance results of both VLSI and image processing applications. Overall, the proposed system is designed by Xilinx ISE 14.5 and the synthesized result is done with ModelSim. Here the biomedical image performance is done by using MATLAB with the adaptation of 2018a. Keywords- Enhanced FIR filter; Adaptive vedic multiplier; Hybrid adder; Biomedical imaging; power delay product;

Design and Evaluation of a 32-bit Carry Select Adder using 4-bit Hybrid CLA Adder

Adder circuits play a remarkable role in modern microprocessor. Adders are widely used in critical paths of arithmetic operation such as multiplication and subtraction. A Carry Select Adder (CSA) design methodology using a modified 4-bit Carry Look-Ahead (CLA) Adder has been proposed in this research. The proposed 4-bit CLA used hybrid logic style based logic circuits for Carry Generate (Gi) and Carry Propagate (Pi) functions in order to improve performance and reduce the number of transistor used. The modified 4-bit CLA is used as the basic unit for implementation of 32-bit CSA. The proposed design of hybrid CLA based 32-bit CSA has been compared with conventional static CMOS based 32-bit CSA and 32-bit Ripple Cary Adder (RCA) by conducting simulation using Cadence Virtuoso. Power consumption and delay in the proposed 32-bit CSA found 322.6 (uW) and 0.556 (ns) whereas power and delay in the conventional 32-bit CSA was 455.4 (uW) and 0.667 (ns) respectively. We have done all the simulation using Cadence Virtuoso 90 nm tool.

Design and Analysis of Multiplier Using High Speed Adders

In all digital signal processing (DSP) applications like FFT, digital filters the main problem faced by processor is its propagation delay. Every high speed signal processing is depends on multiplier circuits. Multiplier performance is directly influenced by the adder design. In this paper, we design low power and high speed carry look ahead (CLA) adder for multiplier circuit by using multi value logic (MVL) based on quaternary signed digits (QSD). The ability of multi value logic (MVL) circuits to achieve more information density and high operating speed when compared to that of existing binary circuits is highly impressive. MVL circuits have attracted important attention for the design of digital systems. Based on quaternary signed digits, the carry look ahead adder is designed, implemented in multiplier circuit and simulated by using cadence virtuoso design suite by 180nF technology.

A high-speed 4-bit Carry Look-Ahead architecture as a building block for wide word-length Carry-Select Adder

A 4-bit Carry Look-Ahead (CLA) architecture for carry-generation process is proposed. CLA architecture proposed in this work uses complex CLA circuits for carry-generation rather than using carry-generate and carry-propagate functions which are used in the conventional process of 4-bit CLA architecture. Performance of the proposed CLA architecture is validated by performing simulation utilizing Cadence tools in standard 45 ​nm CMOS process. In order to prove effectiveness, performance of the proposed 4-bit CLA design is compared with existing 4-bit CLA designs. Moreover, as a possible application of the proposed design and to inspect performance in wide word length adder structure, the 4-bit CLA architectures (proposed and existing) are extended to 16-bits using Carry-Select Adder (CSA) architecture. Both as 4-bit cell and extended 16-bit structure, the proposed 4-bit CLA shows remarkable improvement in speed while maintaining quite acceptable level of power consumption. As a result, the proposed 4-bit CLA can be utilized as a highly suitable substitution of the existing 4-bit CLA architectures in high-speed microprocessor design.

ASIC-based Implementation of Synchronous Section-Carry Based Carry Lookahead Adders

The section-carry based carry lookahead adder (SCBCLA) topology was proposed as an improved high-speed alternative to the conventional carry lookahead adder (CCLA) topology in previous works. Selftimed and FPGA-based implementations of SCBCLAs and CCLAs were considered earlier, and it was found that SCBCLAs could help in delay reduction i.e. pave the way for improved speed compared to CCLAs at the expense of some increase in area and/or power parameters. In this work, we consider semi-custom ASIC-based implementations of different variants of SCBCLAs and CCLAs to perform 32-bit dual-operand addition. Based on the simulation results for 32-bit dual-operand addition obtained by targeting a high-end 32/28nm CMOS process, it is found that an optimized SCBCLA architecture reports a 9.8% improvement in figure-of-merit (FOM) compared to an optimized CCLA architecture, where the FOM is defined as the inverse of the product of power, delay, and area. It is generally inferred from the simulations that the SCBCLA architecture could be more beneficial compared to the CCLA architecture in terms of the design metrics whilst benefitting a variety of computer arithmetic operations involving dual-operand and/or multi-operand additions. Also, it is observed that heterogeneous CLA architectures tend to fare well compared to homogeneous CLA architectures, as substantiated by the simulation results.

High-Performance Design of a 4-Bit Carry Look-Ahead Adder in Static CMOS Logic

Design of a 4-bit Carry Look-Ahead (CLA) process in static CMOS logic has been presented. CLA architecture proposed in this work computes carry-out terms without using carry-propagate and carry-generate signals which are used in conventional static CMOS (C-CMOS) 4-bit CLA adder. Performance parameters of the proposed 4-bit CLA architecture have been simulated and validated by comparing with the conventional design using Cadence design toolset in 45 nm technology. The designs were compared in terms of average power consumption, propagation delay and power delay product (PDP). The proposed 4-bit CLA topology obtained 34.53 % improvement in speed, 4.84 % improvement in power consumption and 37.696 % improvement in PDP while the source voltage was 1.0 V. Hence, as per acquired simulation results, the proposed 4-bit CLA structure is proven to be an excellent alternative to the conventional design for data-path design in modern high-performance processors. Design of a 4-bit Carry Look-Ahead (CLA) process in static CMOS logic has been presented. CLA architecture proposed in this work computes carry-out terms without using carry-propagate and carry-generate signals which are used in conventional static CMOS (C-CMOS) 4-bit CLA adder. Performance parameters of the proposed 4-bit CLA architecture has been simulated and validated by comparing with the conventional design using Cadence design toolset in 45 nm technology. The designs were compared in terms of average power consumption, propagation delay and power delay product (PDP). The proposed 4-bit CLA topology obtained 26.67 % improvement in speed, 5.966 % improvement in power consumption and 31.06 % improvement in PDP while the source voltage was 1.0 V. Hence, as per acquired simulation results, the proposed 4-bit CLA structure is proven to be an excellent alternative to the conventional design for data-path design in modern high-performance processors.

High-Performance Design of a 4-Bit Carry Look-Ahead Adder in Static CMOS Logic

Design of a 4-bit Carry Look-Ahead (CLA) process in static CMOS logic has been presented. CLA architecture proposed in this work computes carry-out terms without using carry-propagate and carry-generate signals which are used in conventional static CMOS (C-CMOS) 4-bit CLA adder. Performance parameters of the proposed 4-bit CLA architecture have been simulated and validated by comparing with the conventional design using Cadence design toolset in 45 nm technology. The designs were compared in terms of average power consumption, propagation delay and power delay product (PDP). The proposed 4-bit CLA topology obtained 34.53 % improvement in speed, 4.84 % improvement in power consumption and 37.696 % improvement in PDP while the source voltage was 1.0 V. Hence, as per acquired simulation results, the proposed 4-bit CLA structure is proven to be an excellent alternative to the conventional design for data-path design in modern high-performance processors. Design of a 4-bit Carry Look-Ahead (CLA) process in static CMOS logic has been presented. CLA architecture proposed in this work computes carry-out terms without using carry-propagate and carry-generate signals which are used in conventional static CMOS (C-CMOS) 4-bit CLA adder. Performance parameters of the proposed 4-bit CLA architecture has been simulated and validated by comparing with the conventional design using Cadence design toolset in 45 nm technology. The designs were compared in terms of average power consumption, propagation delay and power delay product (PDP). The proposed 4-bit CLA topology obtained 26.67 % improvement in speed, 5.966 % improvement in power consumption and 31.06 % improvement in PDP while the source voltage was 1.0 V. Hence, as per acquired simulation results, the proposed 4-bit CLA structure is proven to be an excellent alternative to the conventional design for data-path design in modern high-performance processors.