Anne bracy cs 3410 computer science cornell university the slides are the product of many rounds of teaching cs 3410 by professors weatherspoon, bala, bracy, and sirer. The relationship between the input and the output is based on a certain logic. Reversible gates several reversible gates have been proposed over the years, e. Reversible logic is one of the emerging technologies having promising applications in quantum computing. This advantage of reversible circuits over combinational circuits makes it more efficient. Abstract reversible logic is one of the most vital issue at present time and it has different areas for its application, those are low power cmos, quantum computing, nanotechnology, cryptography, optical computing, dna computing, digital signal. The all optical implementation of reversible logic gates are based on semiconductor optical amplifier soa based machzehnder interferometer mzi. Is reversible logic really advantageous over irreversible. The reversible logic circuits must use minimum number of constant inputs. Within usefully broad limits, logic gates could be treated as ideal boolean devices without concern for electrical limitations. Not, or, and and gates are the basic types of gates. Reversible logic gates, such as the double feynman gate, toffoli gate and peres gate, with 3. Look at the below truth tables for better understanding.
This paper provides the basic reversible logic gates, which in designing of more complex system having reversible circuits as a. Fredkin gate, toffoli gate, interaction gate, and switch gate are typical ones. As the basic elements of any logic circuit, logic gates are used to realize boolean functions. Design of reversible logic circuits using standard cells. In current time, reversible logic gates are being used very fast due to its ability to design a more complex circuit with less power dissipation.
The digital system of qpsk is designed using a reversible logic gates which yields in low. In logic circuits, the toffoli gate also ccnot gate, invented by tommaso toffoli, is a universal reversible logic gate, which means that any reversible circuit can be constructed from toffoli gates. By combining reversible logic gates, reversible circuits can perform complex logical and arithmetic operations. The main purposes of designing reversible logic are to decrease quantum cost, depth of the circuits and the number of garbage outputs. Is reversible logic really advantageous over irreversible logic in circuit design. A combinational logic circuit is reversible iff it contains only reversible gates it has no fanout it is acyclic as a directed multigraph theorem. Logic gates are the basic building blocks of digital circuits or systems. However, the diagrams we use are easier to understand. A gate is an electronic device which is used to compute a function on a two valued signal. Here, we investigate basic properties of reversible logic gates and circuits, which are needed in the following chapters.
Pdf reversible logic gates michael santhiya academia. Bn, that map each input vector to a unique output vector. Fundamentals of reversible logic gates and their applications. Introduction to logic gates not, and, nand, or, nor.
Efficient simulationbased debugging of reversible logic. The advantage of established tools may also not be available. I have designed wallace sign multiplier using reversible logic gates as well. The quantum cost of a reversible gate is the number of 22 reversible gates or quantum logic gates required in designing. Design and comparison of reversible and irreversible. Jun 19, 2019 in this tutorial, we will have a brief introduction to logic gates.
Reversible logic fundamentals reversible gates basic regular reversible structures mirror circuits and spies. Reversible logic gate, quantum bits, mux, sequential circuits. Thus the new device will consume less power and increase device performance. Tech, dept of ece, iec college of engineering and technology, u. Logic circuits are also used in upgraded technical microprocessors, some of which can contain over 100 million gates. We will see the different logic levels in ttl circuits, cmos circuits, some simple logic gates like or, not, nand, and, etc. From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20 computer science cornell university. B reversible logic gates global scientific journal. I am designing reversible logic gates and multiplier circuit using those gates.
The dissipation of heat is negligible and delay is less by using reversible logic gates. Design of all optical reversible logic gates request pdf. Logic gates are the basic building block of digital circuits. What is the exact advantage of reversible computing. Setup in the scf file the input signals as shown below and draw the output f as obtained from simulation. Their advantages and disadvantages are discussed and potential use in biosensing systems, rather than in computing devices, is suggested. Design and implementation of digital components using. Fundamentals of reversible logic gates and their applications piyush singh m. Fpga implementation alu based on reversible logic khushboo ahirwar1, sachin bandewar2, anand kumar singh3 1,2,3 department of electronics and communication, sssce, bhopal abstract programmable reversible logic is emerging as a prospective logic design style for implementation in. This is called boolean logic in a circuit schematic each logic gate is represented by a different picture, like the ones shown below. Conclusion and future scope reversible logic gates form the building blocks of quantum computing. Logic gates are faster when it comes to solving any complex problems. Every future technology will have to use reversible gates in order to. Theresal, shanthi prince abstractconsidering the benefits of quantum and optics, if the logic gates in the quantum field and electronic structure are implemented using optical elements, then it will be benefited from advantages of quantum and design, and these processing.
Implementing the reversible logic has the advantages of reducing gate counts, garbage outputs as well as constant inputs. A number of qcabased reversible logic gates, which are significantly smaller size than cmos have been presented here. The benefits of logical reversibility can be gained only after employing physical reversibility. Reversible logic gates offer significant advantages such as high speed, low power, ease of fabrication etc. A reversible circuit has the facility to generate a unique output vector from each input vector, and vice versa.
Reversible logic is becoming one of the potentialpower optimization techniquesin low power cmos design. Reversible gates uses low power when compared to the conventional logic gates. This project will deal with the design of a 16 bit reversible arithmetic logic unit alu with 15 operations is presented by making use of double peres gate, fredkin gate, toffolli gate, dkg gate and not gate. International journal of scientific research in computer. In this paper the implementation of three types of adder circuits using the reversible gate r are presented 1. Mar 31, 2015 a number of qcabased reversible logic gates, which are significantly smaller size than cmos have been presented here. An output of one logic gate can be an input to another logic gate. Bennett 3 showed that zero energy dissipation would be possible if the network consists of reversible gates only. Ashraful haque department of electrical and electronic. A new approach of presenting reversible logic gate in.
Logic gates types, working principle, application, advantage. The fundamental physical concepts behind reversible logic. A reversible circuit must have as many input wires as output wires permute the set of input values. This paper gives an overview of the reversible logic gates gathered from literature surveys. Introduction basic concepts required to understand the reversible logic gates. Mechanical computing systems using only links and rotary. Therefore, as a proof of the fact that links and rotary joints su ce to create the combinatorial logic required for a turingcomplete computing system, fig. What is the difference between reversible logic gates and.
Main goals of reversible logic synthesis is to minimize the garbage, to minimize the delay, to minimize the total number of gates, to minimize the width of the circuit. The reversible logic gates are ninput and noutput logic gates. Also, circuits designed using these circuits would have better performance as compared to existing circuits. Design constraints for reversible logic circuits 4. Logic gates actually look like weird bugs in real life. This forms the basis of reversible logic where we have only one is to one correspondence bw the input and the output. The first condition for any deterministic device to be reversible is that its input and output be uniquely retrievable from each other then it is called logically reversible. The number of triples of balanced functions is equal to 70 70 70 343 000 however, the number of reversible 3,3 gates is much smaller. Digital logic circuits types, application, advantage and disadvantage. From transistorsto logic gates and logic circuits prof. In reversible logic, the fanout of every signal, including primary inputs is one. Design of sequential circuits using reversible logic has been presented in 7 and 8.
Introduction to reversible logic and mathematical derivation. Reversible logic is similar to the convention logic but reversible logic circuits are constructing by reversible logic gates and conventional logic gates are designed by normal gates i. Fredkin gate a block diagram b schematic representation. Pdf a low power adder using reversible logic gates editor. In computer switching circuits, in which the logical boolean operation on data performed are called logic circuits or a circuit for performing the logical operations. Addition, subtractions operations are realized using reversible dkg gate and it compare with conventional gates. The energy savings of reversible logic gates is due mostly to the fact that they do not require entropy be created when an operation is performed. Mechanical computing systems using only links and rotary joints.
Sequential division circuit using reversible logic gates. This basic logic gate is the combination of and and not gate. The goal of this paper is to develop a method to build singleoutput reversible logic circuits in regular and nonregular structures, in binary and ternary logic, with minimized number. Design and implementation 16 bit reversible logic alu with 15. One of the most important features of a reversible gate is its garbage output i. There are several advertised advantages to fredkin gates that do not necessarily work as expected in real circuits. Reversible logic circuits should have minimum quantum cost. Advantages of ttl logic family, one should have a basic idea about rtl, dtl etc.
Also in the synthesis of reversible circuits direct fan out is not allowed as onetomany concept is not reversible. The reversible 11 gate is not gate with zero quantum cost is as shown in the figure 1. It is an electronic circuit having one or more than one input and only one output. Basically, all logic gates have one output and two inputs. This creates trees of gates that depend on each other. Reversible logic gates helps to determine the outputs from the inputs and also the inputs can be uniquely recovered from the outputs. Logical operations are performed using boolean algebra which makes the circuit design more economical and simple. Next, the previously proposed alu in the literature. A logic circuit consists of a number of a logic gates. Final advantages and disadvantages of reversible managed lanes january 2010 atlanta regional managed lanes system plan georgia department of transportation, office of planning 2 distance highway trips within activity centers or from closer suburban areas to nearby. It is also known as the controlledcontrollednot gate, which describes its action. Abstractconsidering the benefits of quantum and optics, if the logic gates in the quantum field and electronic structure are implemented using optical elements. Reversible logic reversible logic realizes functions f. Based on this, logic gates are named as and gate, or gate, not gate etc.
Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum. In a model of computation that uses deterministic transitions from one state of the abstract machine to another, a necessary condition for reversibility is that the relation of the mapping from nonzeroprobability states to their successors must be onetoone. Design of control unit for low power au using reversible logic. In the second part, a new method for converting irreversible functions to the reversible ones in qca technology is presented. A gate or circuit that does not loose information is called reversible. Three articles that discuss some possible implementations of reversible logic and provide references to further reading are helical logic, by ralph c. Reversible logic fundamentals reversible gates basic. Diode logic dl uses diodes to implement logical functions like and and or. Sep 10, 2017 a gate or circuit that does not loose information is called reversible. Reversible logic gates has received great attention on power dissipation. Basic logic gates types, functions, truth table, boolean.
Reversible computing is a model of computing where the computational process to some extent is time reversible. Final advantages and disadvantages of reversible managed lanes january 2010 atlanta regional managed lanes system plan georgia department of transportation, office of planning 3 safety reversible facilities require additional safety precautions when compared to their bidirectional counterparts. In modern technology logic circuits are found in several hightech devices including arithmetic logic units, computer memory and registers, multiplexers and decoderencoder. Review ontypesnumber of reversible logic gates and basic. Chapter 2 quantum gates when we get to the very, very small worldsay circuits of seven atomswe have a lot of new things that would happen that represent completely new opportunities for design. Reversible gates some of the important reversible logic gates are. Reversible circuits are of particular interest in low power cmos vlsi design. The design can be optimized so as to produce minimum number of garbage outputs. In this chapter we will look at the types of logic gates used within circuits and how the notions of logic gates need to be modi. In reversible logic design, there is k no of output fork no of inputs. Also, logic gates are the building blocks of digital. Not, and, or, and xor there are also other ones, such as nand, nor, and xnor that were not going to cover.
A reversible logic gate is a memoryless logic element that realizes an injective logical function. Reversible electronic logic using switches pdf, by ralph c. A reversible circuit g consists of a cascade of reversible gates g i, i. Landauer has shown that for irreversible logic computations, each bit of. Reversible circuits are fundamentally different from traditional irreversible ones. In addition, qca design accomplished by the basic gate and logic circuit in which less area is required to make a device. Ashraful haque department of electrical and electronic engineering islamic university of technology, board bazar, gazipur1704, bangladesh.
A truth table lists all possible combination of inputs and the corresponding outputs. The machzehnder interferometer has advantages such as high speed, low power, easy fabrication and fast switching time. The interconnection of gates to perform a variety of logical operation is called logic design. The three gates or, and and not, when connected in various combinations, give us basic logic gates such as nand, nor gates, which are the universal building blocks of digital circuits. Next will be discuss reversible arithmetic, specifically adders and comparators. The circuit actually operates in a backward operation, allows reproducing the inputs from the outputs and consumes zero power. A new design and simulation of reversible gates in quantum. Some logic gates like not gate or inverter has only one. Development of tool for mapping conventional circuit to reversible. Digital logic or gate digital gates electrical technology. Design of all optical reversible logic gates kuki bordoloi, t.
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