Sparse tree adder circuit

摘要

An adder circuit is provided that includes a propagate and generate circuit stage to provide propagate and generate signals, a plurality of carry-merge stages to provide carry signals based on the propagate and generate signals and a conditional sum generator to provide conditional sums based on the propagate and generate signals. The conditional sum generator includes ripple carry gates and XOR logic gates. The adder circuit also includes a plurality of multiplexers to receive the carry signals and the conditional sums and to provide an output based on the input signals.