Design and Simulation of a Modified Architecture of Carry Save Adder

This paper presents a technology-independent design and simulation of a modified architecture of the Carry-Save Adder. This architecture is shown to produce the result of the addition fast and by requiring a minimum number of logic gates. Binary addition is carried out by a series of XOR, AND and Shift-left operations. These operations are terminated with a completion signal indicating that the result of the addition is obtained. Because the number of shift operations carried out varies from 0 to n for n-bit addends, a behavioral model was developed in which all the possible addends having 2- to 15-bits were applied. A mathematical model was deducted from the data and used to predict the average number of shift required for standard binary numbers such as 32, 64 or 128-bits. 4-bit prototypes of this adder were designed and simulated in both synchronous and asynchronous modes of operation