Carry circuitry for LUT-based FPGA

iranian journal of electrical and electronic engineering, 2019

An efficient Lookup Table (LUT) design for memory-based multiplier is proposed. This multiplier can be preferred in DSP computation where one of the inputs, which is filter coefficient to the multiplier, is fixed. In this design, all possible product terms of input multiplicand with the fixed coefficient are stored directly in memory. In contrast to an earlier proposition Odd Multiple Storage (OMS), we have proposed utilizing Even Multiple Storage (EMS) scheme for memory-based multiplication and by doing so we are able to achieve a less complex and high-speed design. Because of the very simpler control circuit used in our design, to extract the odd multiples of the product term, we are also able to achieve a significant reduction in path delay and area complexity. For validation, the proposed design of the multiplier is coded in VHDL, simulated and synthesized using Xilinx tool and then implemented in Virtex 7 XC7vx330tffg1157 FPGA. Various key performance metrics like number of sli...

2018 International Conference on Signals and Systems (ICSigSys)

Short Word Length (SWL) DSP systems offer good performance as they process less data-typically up to three bits. Short Word Length systems may be designed using the FPGAs. FPGAs come with many built-in primitives like Look-up tables, Flip-flops, additional Carry logic, Memories and DSP elements.All these primitives give alternative approaches for FPGA based system design. This paper presents a way to use the Look-up tables to design three bit (3×3) constant coefficient unsigned integral multiplier for Short Word Length DSP systems.Besides, the feasibility of using Block ram and DSP elements for Short Word Length DSP system (multiplier) is also carried out as an alternative implementation approach.Result suggests the proposed way be the better one when compared with other two implementations.

The delay is same for small size operands and this redundant adders require more hardware resources than carry propagate adders. Therefore, carry-save adders are not usually implemented on FPGA devices, although they are very useful in ASIC implementations. In this paper we have showed that it is possible to implement redundant adders with a hardware cost close to that of a carry propagate adder.

International Journal of Scientific Research in Science and Technology, 2022

A methodology for constructing low-error, high-efficiency approximate adders has been provided in this project. To reduce the inaccuracy of approximation adders, the suggested solution effectively utilizes FPGA resources. We propose two approximate adders for FPGAs using our methodology: low error as well as area efficient approximate adder (LEADx), as well as area as well as power efficient approximate adder (APEx). Both approximate adders are composed of an accurate as well as an approximate part. The approximate parts of these adders are designed in a systematic way to minimize the mean square error (MSE). LEADx has lower MSE than the approximate adders in the literature. APEx has smaller area as well as lower power consumption than the other approximate adders than the existing adders. As a case study, In video encoding applications, approximation adders are employed. In the video encoding application, LEADx outperformed the other approximation adders. As a result, our proposed approximate adders can be used to create error-tolerant applications in FPGAs with efficiency. The effectiveness of the proposed method is synthesized as well as simulated using Xilinx ISE 14.7.

In this paper 2 different multiplier architectures are implemented in Xilink FPGA and compared for their performance. Here these architectures are implemented for 4,8,16 bit Based on various speed-up schemes for binary multiplication, a comprehensive overview of different multiplier architectures are given in this report. In addition , it is found that booth multiplier is faster than array multiplier.

In this paper we present a self-con gurable multiplication technique allowing variable con guration time for a class of LUT based Field Programmable Gate Arrays (FPGAs) which exist today. We show this technique to be implementable on FPGA architectures allowing internally addressable RAM primitives to be d i r ectly mapped t o the Logic Elements (LEs) of the logic resource. This provides run-time read/write addressing capabilities to the FPGA logic elements, which in turn is viewed as an FPGA possessing a run-time recon gurable logic resource. As an emerg i n g e l d o f c omputing research, recon gurable computing provides an area/time tradeo that is actively investigated b y m a n y r esearchers. We base the variable parameter for our multiplier on the recon guration time required and present results showing the e ective area/time performance for multipliers of varying input bit size. Results indicate the achievable increase in functional density for multiplication on FPGAs implemented utilising recon guration.

IJSRD, 2013

The multiplication is major arithmetic operation in signal processing and in ALU's .The multiplier uses look-up-table (LUT) as memory for their computations. However, we do not find any significant work on LUT optimization for memory-based multiplication. A new approach to LUT design was presented, where only the odd multiple storage (OMS) scheme. In addition to that the antisymmetric product coding (APC) approach, the LUT size is reduced to half and provides a reduction. When APC approach is combined with the OMS technique, the two's complement operations could be simplified since the input address and LUT output could always be transformed into odd integers, and thus reduces the LUT size to one fourth of the conventional LUT. The proposed LUT multipliers for word size L=W=5 bits are coded in VHDL and synthesized in Xilinx 14.2. It is found that the proposed LUT-based multiplier involves comparable area and time complexity for a word size of 5-bits.

The multiplication operation is present in many parts of a digital system or digital computer and also in signal processing, graphics and scientific computation. With advances in various technologies, various techniques have been proposed to design multipliers, with high speed, low power consumption and lesser area. Various high speed low power compact VLSI implementations are possible only with multipliers. This project presents a highspeed and low area 16×16 bit Modified Booth Multiplier (MBM) with Carry Select Adder (CSA) and 3-stage pipelining technique. These techniques to improve the performance by reducing the time delay. These multiplication techniques are design using hardware description language (HDL) and it can simulate using modelsim software and also it will implement in Spartan 3E FPGA and also power consumption will estimate using tanner EDA tool.

Abstract—The aim of this paper is to design and implement the Arithmetic circuits (adder & multiplier) for digital signal processing applications and it is accomplished using Xilinx family Virtex-5 XC5VLX30-3-FF243 Field Programmable Gate Array (FPGA) device. Since in this technological era, the application of digital signal processing is very wide and it will enhance in the future as well. The operations performed in the digital signal processing domain are the combination of addition and multiplication, the arithmetic circuits (adder & multiplier) are the core of DSP hardware. In this paper, different types of adder multiplier circuits have been implemented on Field Programmable Gate Array (FPGA) and an analysis has been done to find out the most applicable arithmetic circuits for FPGA based digital signal processing implementation. The analysis of implementation result is presented with respect to area, delay and power for 8 bit, 16 bit, 32 bit and 64 bit circuits and it can be realized to implement the fixed-point arithmetic circuits in field programmable gate array (FPGA).

An adder is a digital circuit that performs addition of numbers. In many computers and other kinds of processors in the arithmetic logic units, adders are used. In other parts of the processor, they are also utilized. Where they are used to calculate addresses, table indices, increment and decrement operators, and similar operations. Although adders can be constructed for many number representations, such as BINARY-DECODED DECIMAL or EXCESS-3, the most common adders operate on binary numbers. We designed an adder which is of high speed and applied this to a new multiplier for better performance multiplier by using CARRY SELECT ADDER in this project. In arithmetic operations, addition and multiplication are having a major role. When the number of bit increases, the complexity of the adder circuits increases and the speed performance decreases. The delay will be very much reduced proposed carry select adder based multiplier on comparing with carrying look ahead adder based multiplier, and the carry save adder based multiplier. The code is written in VHDL and Verilog and synthesized the design in Xilinx ISE 14.1.