Tradeoffs in parallel prefix adder structures
This report presents the results of research on comparing the structures and qualities of fast parallel prefix adders. The binary adder serves as a fundamental component of many digital arithmetic operations. Many modern microprocessors and ASICs that require high speed arithmetic logic often implement parallel prefix adders. Modern parallel prefix adder structures are based on previous works including those of Kogge-Stone, Brent-Kung, Ladner-Fischer, Knowles, et al. and designs presented in each work have their own merits and tradeoffs that are suitable for certain applications. Previous works have described standard and systematic ways to design and construct functional parallel prefix adder structures. Although the parallel prefix adder has been studied for decades, this work explores the possibility that non-standard and more optimal structures may exist by developing and utilizing a brute force search algorithm based on the prefix operator rules and properties to find all possible parallel prefix adder structures. The parallel prefix adder search algorithm design, search results and study of tradeoffs are discussed in this work.