Analysis of various Approximate adders in Ripple Carry Adder design.

In this paper various types of approximate full adders are used and tested on ripple carry adder RCA (both 4 bit as well as 8 bit RCA) by replacing them in different bit positions and have been tested for various parameters. Approximation circuits are actually used to reduce the design compilation and to increase the performance. In applications like multimedia the required information could be collected from slightly erreraneous outputs and hence there is no need of producing exact results. In those applications the approximate adders could be used. In this paper various types of approximate full adders are used and tested in different bit positions of ripple carry adder. All approximate adders are compared interms of error percentage and performance.