Design And Research Of Logic Circuits Based On Quantum Dot Cellular Automata

Along with the advancement in large-scale integrated circuit, especially VLSI, theenergy dissipation of integration circuit has been a severe challenge to the development ofelectronics industry. At present, the integration of computer chips increases double for a yearand a half. However, in fact, Moore’s law will lost of function when the line width ofintegration circuit kept reducing. The results of the study show the size of the transistor willreach its physical limits. Therefore, in1993Lent proposed a new device which is differentfrom the traditional device structure: Quantum dot cellular automata (QCA). QCA provides anew type of information processing method, different from the traditional electronic circuits,it is through the coulomb’s law to transfer information instead of the traditional voltage level.Design of logic circuits based on QCA possesses the advantage of high level of integration,low power consumption and high speed, more attention is paid gradually to the study of QCA.Based on the analysis of leading features of QCA and the existing design method, mainresearch work is listed as follows.(1) Design of combinational logic circuits based on QCAQCA cells can be used to implement gates and QCA wires. On the basis of these QCAfeatures, many combinational logic circuits are designed in this paper: full adder, substracter,decoder and encoder. On the one hand, a new one bit full adder was proposed in the paper. Wecompare the proposed full adder structure with the lastest and best full adder design and thecomparison result indicates the proposed design is consume smaller area and also has lessercomplexity. On the other hand, the paper proposed a design method of2-4decoder, thismethod makes a masterly method to avoid the wire crossings. There is a certain facilitation ofQCA logic circuit design in this method.(2) Design of sequential logic circuits based on QCAThe basis features of QCA also apply to design of sequential logic circuits. On the basisof these QCA features, many sequential logic circuits are designed in this paper: SR flip-flop,D flip-flop, JK flip-flop, T flip-flop, four bit shift register. On the one hand, the paperanalyzes the design method of sequential logic circuits based QCA: analysis characteristics,find the characteristic equations, draw the QCA layout, simulate and analysis the layout. Onthe other hand, the paper also introduces the design method of sequential logic circuits bycombination Fredkin gate.