International Research Journal of Engineering and Technology (IRJET)
Volume: 04 Issue: 03 | Mar -2017
www.irjet.net
e-ISSN: 2395 -0056 p-ISSN: 2395-0072
LOW POWER AREA EFFICIENT ARITHMETIC AND LOGICAL CONTROL UNIT USING REVERSIBLE LOGIC Karthikeyan. S1, 1Assistant
Priyanga. K2,
Priyanka. P3,
Vigneshkumaran. A4
Professor, Department of ECE, Jansons Institute of Technology, Coimbatore, Tamil Nadu, India
2,3,4Students,
Department of ECE, Jansons Institute of Technology, Coimbatore, Tamil Nadu, India
---------------------------------------------------------------------***--------------------------------------------------------------------unique output as per quantum mechanics and so as to be mapped as one to one. This kind of output can be useful to get the inputs given and also reduce the loss of power. Quantum mechanics play a vital role in the construction of reversible logic or the quantum gates.
Abstract - In this project we are designing a 8 bit
arithmetic and logical unit with the help of reversible logic. This ALU consists of 10 operations, 4 logical and 6 arithmetic operations. The logical operation include and, or, ex-or and ex-nor. The arithmetic operation performed by this gate includes set, clear, increment, 1’s complement, 2’s complement and transfer of input. Reversible logic is gaining interest in the recent years due to its less power consuming and less heat dissipating characteristics. Unlike the irreversible gates that dissipates energy, the reversible computation reduce heat dissipation. The loss of information is associated with loss in physics is requiring that one bit information lost dissipates “KT ln2 of energy”. In order to overcome the loss of information we go for reversible computation. The parameters that define an optimum reversible logic based ALU are low quantum cost, reduced garbage outputs and minimum number of reversible gates used. Based on the above constraints of the reversible logic we have designed a ALU with single reversible logic gate namely RC-1 gate. This design is developed using Xilinx 13.4suite, verilog software. It is designed so as to perform 8 bit inputs for both logical and arithmetic operations.
1.1 REVERSIBLE LOGIC: Reversible are circuits that have one to one mapping between vectors of inputs and outputs, thus the vector of input states can be always reconstructed from the vector of output states. Reversible circuit can realize unbalanced function only with additional inputs and garbage output. In conventional logic gate the 2 inputs form a single output, which leads to the power dissipation in the form of heat. This was found by Landauer and the scientist Bennet proved it to be true by defining the loss of heat in terms of KT ln 2 joules. The reversible logic is formed in order to reduce this dissipation in the way that both the inputs are involved to give 2 sets of output that is believed to t the same. It also provides the unique output and output can be used to retrieve the inputs as they are one to one mapped.
Key Words: RC-1 gate, reversible computation, garbage
1.2 REVERSIBLE LOGIC GATES:
1.INTRODUCTION:
A reversible logic gate is an n-input n-output logic devices with one-to-one mapping. This helps to determine the outputs from inputs and also inputs can be uniquely recovered from outputs. A reversible circuit should be designed using minimum number of reversible logic gate. Reversible logic gate consists of garbage output and quantum cost. Garbage output refers to the number of unused output present in a circuit, which cannot be avoided as these are very essential to achieve reversibility. Quantum cost refers to the cost of the circuit in terms of cost of primitive gate (1*1 or 2*2).
outputs, quantum cost; arithmetic and logic operations.
The recent research in VLSI technology is the reversible logic to reduce the power dissipation is the major area of concern. The reversible logic is associated with the combinational circuits without the delay or flip-flops. This was first brought out by Landauer who discovered the power dissipation in conventional or irreversible gates. He stated that only one of the inputs out of 2 given input is given to the output information and the other bit is dissipated. This power loss is major disadvantage in conventional gates. Bennet gave a mathematical proof to this power dissipation is in the form of KT ln 2. This led to the development of reversible logic. The concept of the reversible logic focuses on the equal number of input and outputs. In case of reversible logic each input gives an
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