标题: 以改良式冗余算术座标旋转演算法所设计之直接数位频率合成器
Area Efficient Direct Digital Frequency Synthesizers using Modified Redundant CORDIC Algorithms
作者: 陈立京
Li-Jing Chen
吴文榕
Wen-Rong Wu
电信工程研究所
关键字: 直接数位频率合成器;座标旋转演算法;Direct Digital Frequency Synthesizer;CORDIC
公开日期: 2001
摘要: 在本篇论文中,我们将探讨将座标旋转(CORDIC)演算法与其在直接数位频率合成器(DDFS)上的应用。CORDIC是一种可以利用移位器与加法器来处理旋转运算的演算法,然而二进位的CORDIC处理器的速度瓶颈受限于加法器的进位传递,利用冗余二进位(redundant binary)算术法即可改善此问题。在本论文中我们提出二个较有效率之改善架构,基本的构想是要减少角度旋转运算的范围以使旋转运算级减少,然而因为旋转范围减小,所以还需要额外的查表器来储存旋转的起始点,这个构想我们以双旋转法与重新编码法来实现。最后这二种改良的架构皆由Verilog硬体描述语言设计,并藉由Avant! 0.35μ标准电路单元以Synopsys合成工具合成。在原有八级的设计下移除前二级的旋转级,分别可以节省硬体面积达30%与50%以上。在适当的路径下使用管线式架构,使得此二种改良架构皆可在350MHz的时脉频率下正常运作。
In this thesis, we discuss the CORDIC algorithm and its applications on the direct digital frequency synthesizer (DDFS). The CORDIC algorithm is a well-known iterative method for the vector rotation computations, which can be implemented by regular shifters and adders. However, the throughput of conventional binary arithmetic CORDIC processor is limited by the carry-propagation of the adders. Recent researches have taken advantage of the carry-free characteristic of redundant number arithmetic to speed up CORDIC operations. In this thesis, we propose two efficient redundant CORDIC algorithms. Our idea is to reduce the angle rotation range such that the number of processing stage can be reduced. Since the rotation range is reduced, multiple initial vectors are required, which are stored in a lookup table. This idea is then realized using the double rotation and recoding CORDIC algorithms. Finally, the two proposed architectures are designed by Verilog hardware description language, and then synthesized by Synopsys Design Complier using Avant! 0.35μm standard cell library. Removing two stages from original designed eight-stage-CORDIC, we can reduce the hardware area more than 30% and 50%, respectively. Both architectures can be operated in 350MHz clock frequency using appropriate data-path pipelining.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT900435048
http://hdl.handle.net/11536/68924
显示于类别:Thesis