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文献〔1〕根据任意开关函数可表示成某些变量重复的对称函数,即开关函数的加权表达式,提出了基于一位全加器的加权网络的代数综合算法。由于一位全加器的集成度低,因此需用较多的集成块。本文对文献〔1〕的算法作了改进,使之适用于四位全加器的情况。 四位二进制全加器的图形符号如图1所示。A_3～A_0、B_3～B_0为二个四位二进制数输入,C_0为低位进位输入,S_3～S_0为本位和输出,C_4为进位输出。其输出可表示为 C_4S_3S_2S_1S_0=A_3A_2A_1A_0+B_3B_2B_1B_0 +C_0 （1）式中“+”为二进制加法运算。
According to [1], an arbitrary algebraic switch function can be expressed as a repeated symmetric function of some variables, that is, a weighted expression of a switch function. An algebra synthesis algorithm based on a full adder-weighted network is proposed. Due to the low level of integration of a full adder, more manifolds are required. In this paper, the algorithm of [1] has been improved to make it suitable for four full adders. Four binary full adder graphic symbols as shown in Figure 1. A_3 ~ A_0, B_3 ~ B_0 are two four-digit binary input, C_0 is low carry input, S_3 ~ S_0 is basic and output, C_4 is carry output. The output can be expressed as C_4S_3S_2S_1S_0 = A_3A_2A_1A_0 + B_3B_2B_1B_0 + C_0 (1) where “+” is a binary addition.