The low-power design of prefix adder

Graduation date: 1998Minimizing the dynamic power consumption of a circuit is becoming a more and more important issue for digital circuit design in the age of portable electronics. Among all the arithmetic circuits, addition is the most fundamental operation. Therefore, designing low power adder is an important and necessary research area.\ud In this thesis, the dynamic switching power consumption of ripple carry adder, carry look ahead adder, carry skip adder, carry select adder, and prefix adder are discussed. The power factor, the sum of products of probability and fan-out of all internal nodes, is presented. This thesis also studies the power and time trade-off with efficiency index which is the product of power factor and worst case gate counts. The result shows that the carry look ahead adder has the lowest efficiency index in the design of a 64 bit adder. The carry skip adder is the best one in a design of a 16 and 32 bit adder. The ripple carry adder is the best choice for an 8 bit adder.\ud This study also presents a low power prefix adder design which will reduce the power consumption of the prefix adder without lost of performance