KOGGE STONE ADDER
The Kogge -Stone tree achieves both (log2N) stage and fan-out of 2 at each stage. This comes at the cost of many long wires that must be routed between stages. The tree also contains more PG (propagate and generate) cells. While this may not impact the area if the adder layout is on a regular grid however it will increase the power consumption. The cell diagram notations are given in Fig. 5.The resultant 16 bit carry generation topologies are shown in Fig.6The delay and power calculation (using standard 90nmCMOS technology) of various length Kogge- Stone Adders are shown.