Comparative Analysis of Optimization Schemes of Carry Look-ahead Adder

Abstract

Abstract Conventional CLA adder has has a large number of transistors and high input impedance, which affects various performance aspects, resulting in high delay and power consumption. Therefore, to increase the performance and reduce delay, several optimized structures of CLA are proposed. From the perspective of structure and power, this paper selects four different design schemes and uses Cadence Virtuoso 90nm technology to compare and analyze the optimization results in aspects of circuit area, delay and power consumption. The analysis results show that the conventional 4-bit adder structure can be improved by designing the carry term Field Effect Transistor (FET) network and replacing the existing gate circuit with a hybrid Gate diffusion technology (GDI) gate, which can reduce the number of transistors and the design circuit area. They also contribute to improving the power consumption, delay, power delay product (PDP) and other performance parameters. Pipeline technology and multi-layer CLA block technology are suitable for carry look-ahead adder with more bits and longer carry chain, which can shorten carry propagation time, further optimize processor performance and improve CPU computing efficiency.