Parallel Prefix Adders

Design and Characterization of Parallel Prefix Adders using FPGAs David H. K. Hoe, Chris Martinez and Sri Jyothsna Vundavalli break away of Electrical Engineering The University of Texas, Tyler dhoe@uttyler.edu ? AbstractParallel-prefix common vipers (also known as carry channelize common vipers) ar known to contrive the best carrying into action in VLSI designs. However, this carrying into action advantage does not translate directly into FPGA implementations due to constraints on logic crush configurations and routing overhead. This paper investigates three types of carry-tree common vipers (the Kogge-Stone, sparse Kogge-Stone, and spanning tree common viper) and comp atomic number 18s them to the mere(a) Ripple harbour Adder (RCA) and ravish edit out Adder (CSA). These designs of vary bit-widths were implemented on a Xilinx ascetic 3E FPGA and hold in measurements were made with a high-performance logic analyzer. due to the mien of a fast carry-chain, the RC A designs exhibit better delay performance up to 128 bits. The carry-tree adders are expected to have a recreate advantage over the RCA as bit widths move up 256. described. An efficient testing strategy for evaluating the performance of these adders is discussed.

Several tree-based adder structures are implemented and characterized on a FPGA and compared with the Ripple Carry Adder (RCA) and the Carry Skip Adder (CSA). Finally, some conclusions and suggestions for correct FPGA designs to enable better tree-based adder performance are given. II. CARRY-TREE adder DESIGNS Parallel-prefix adders, also known as ca rry-tree adders, pre-compute the propagate a! nd generate signals [1]. These signals are variously combine using the fundamental carry factor (fco) [2]. (gL, pL) ? (gR, pR) = (gL + pLgR, pL pR) (1) Due to associative property of the fco, these operators can be combine in different ways to form various adder structures. For, example the four-bit carry-lookahead generator is given by: c4 = (g4, p4) ? [ (g3, p3) ? [(g2, p2) ? (g1, p1)] ] (2) A unanalyzable rearrangement...If you want to get a full essay, order it on our website: BestEssayCheap.com

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