Design Of Carry-Lookahead Adder Based On 55nm

As the semiconductor industry faces technology barriers,the independent design of highperformance integrated circuits plays a crucial role in safeguarding national security and promoting scientific and technological development.Addition operation,as one of the basic operations in digital circuits,has significant applications in areas such as arithmetic operations,signal processing,and communication systems.The operation speed and circuit power consumption have a significant impact on the overall circuit performance.Therefore,the optimization of adder circuit design is of paramount importance.This thesis conducts an in-depth study of adder circuits.First,the working principles of different types of adders are analyzed,including ripple carry adders,carry bypass adders,carry select adders,and carry lookahead adders.Next,various carry tree structures are compared,such as Sklansky trees,Kogge-Stone trees,Brent-Kung trees,Han-Carlson trees,and Knowles trees.Subsequently,static and dynamic circuit design methods are investigated.Finally,mainstream types of clock circuits are discussed,including single-phase and multi-phase clocks.After carefully weighing the advantages of various design choices,the design adopts a multiphase clock-driven domino dynamic logic circuit based on the Kogge-Stone tree structure.The dynamic logic circuit structure and dimensions are further optimized to improve the adder’s performance through theoretical analysis and simulation.Moreover,critical paths are analyzed to identify timing-constrained paths and take measures to reduce delay.The design adopts a hierarchical approach,dividing the overall design into four functional modules:clock tree,carry signal,carry tree,and sum selection.The clock tree module generates six sets of stable clock signals based on the buffer tree structure.The carry signal module is responsible for generating the required carry generation and carry propagation signals for subsequent use.The carry tree module,based on the Kogge-Stone tree,generates carry signals for each input through a five-level carry tree.The sum selection module selects the correct sum results and outputs them according to the output signals of the carry tree.Carry signal generation and carry tree adopt dynamic logic to accelerate operation speed,while the clock tree and sum selection employ static structures to enhance driving capability.Using the 55nm CMOS process,this study completes the schematic design and layout implementation of a 32-bit high-speed adder.The design’s functional correctness is verified through pre-simulation and post-simulation.Under the TT process corner at 27℃,the adder’s clock frequency is 3.84 GHz,the critical path delay is 356 ps,the average power consumption is 12.3 mW,and the total layout area is 13,310 μm2.