Acta Scientiarum Naturalium Universitatis Pekinensis

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An Improvement on Carry Chain of Conditional Carry Selection

WU Ke1, GAN Xuewen, ZHAO Baoying   

  1. Institute of Microelectronics, School of Electronics Engineering and Computer Science, Peking University, Beijing, 100871; 1E-mail:
  • Received:2005-03-02 Online:2006-05-20 Published:2006-05-20



  1. 北京大学信息科学技术学院微电子研究院,北京,100871;1E-mail:

Abstract: An improved conditional carry selection (CCS) circuit is proposed in this paper. The new circuit is compared with the conventional conditional carry selection structure for a 4-bit adder. The two circuits were simulated by SPICE under the same condition and the results show that the propagation time of carry and sum (C3 and S3)of 4-bit adder are reduced 34.39% and 33.95%, respectively.

Key words: carry chain, adder, CCS, CSS, propagation time

摘要: 介绍了一种对加法器CCS进位链的改进电路,并与没有进行改进的传统的CCS进位链电路进行比较。对这两种电路结构在同样的条件下用SPICE模拟。从实验结果中可以看到,4-bit的加法器单元的进位传输延迟时间缩短了34.39%,并且第4位和的传输延迟时间缩短了33.95%。

关键词: 进位链, 加法器, CCS, CSS, 传输延迟时间

CLC Number: