In recent years reversible logic has offered a promising alternative to traditional logic circuits. Reversible logic introduces a mechanism which allows theoretically zero energy \ndissipation by eliminating the possibility of information loss. However, it is also desirable \nthat all computation should ideally be done in a fault tolerant manner. To address this we \npropose techniques to achieve fault tolerance in reversible logic based on a passive hardware redundancy technique. We propose two new designs for a reversible majority voter circuit that can be used to implement fault masking. Comparisons to existing designs are presented in terms of cost metrics such as gate count, garbage outputs, constant inputs, and quantum cost. Comparative failure probability analysis of the proposed voter circuits is also provided. Simulation results of the voter circuit failure probabilities over different numbers of trials are also presented. Our approach can be used to determine the circuit failure probability by using the gate failure probabilities. The proposed methodology can provide useful information for future reversible gate fabrication and designing future fault tolerant reversible circuits.
In recent years reversible logic has offered a promising alternative to traditional logic circuits. Reversible logic introduces a mechanism which allows theoretically zero energy \ndissipation by eliminating the possibility of information loss. However, it is also desirable \nthat all computation should ideally be done in a fault tolerant manner. To address this we \npropose techniques to achieve fault tolerance in reversible logic based on a passive hardware redundancy technique. We propose two new designs for a reversible majority voter circuit that can be used to implement fault masking. Comparisons to existing designs are presented in terms of cost metrics such as gate count, garbage outputs, constant inputs, and quantum cost. Comparative failure probability analysis of the proposed voter circuits is also provided. Simulation results of the voter circuit failure probabilities over different numbers of trials are also presented. Our approach can be used to determine the circuit failure probability by using the gate failure probabilities. The proposed methodology can provide useful information for future reversible gate fabrication and designing future fault tolerant reversible circuits.
Reversible logic circuits have received emerging attentions in recent years. Reversible logic is widely applied in some new technical fields, such as quantum computing, nanocomputing and optical computing and so on. In this paper, three fault tolerant gates are proposed, ZPL gate, ZQC gate and ZC gate. By using the proposed gates, fault tolerant quantum and reversible BCD adder and skip carry BCD adder are designed, which overcome the limitations of the existing methods. The proposed reversible BCD adders have also parity-preserving property. They are better than the existing counterparts, especially in the quantum cost. Proposed designs have been compared with existing designs with respect to the number of gates, number of garbage outputs and quantum cost.
Reversible logic is the emerging topic for research due to its advantage of low energy consumption. Fault tolerant circuit design is required to give error free outputs. In this paper we present an optimized n bit Reversible Fault Tolerant Comparator design using parity preserving reversible logic gates. The Design involves MSB comparison as the first stage followed by Next Bit comparison stage which contributes for 1 bit garbage-less comparator design. The Design is generalized for n bit comparison. The performance parameters are analyzed for n bit. Our work outperforms the existing reversible fault tolerant comparator designs in terms of garbage output and Ancilla inputs or constant inputs. This efficiency of our design helps in reducing the footprint of the design.
Reversible logic has drawn great attention in recent years due to its emerging propagation in diverse range of areas. In this paper, we present a novel approach to unite addition and subtraction operations; circuits that perform addition/subtraction operations using fault tolerant reversible gates with fault detection capability. Adder and subtractor are basic building blocks of any Arithmetic Logic Unit; in this manner we first present the concept of merging those two circuits into one logical block. Then we introduce all possible approaches to construct fault tolerant united addition-subtraction circuit for not only reducing the number of gate but also minimizing quantum cost and garbages of circuit at a meaningful level. We demonstrate three types of half-adder/subtractor circuits and four types of full-adder/subtractor circuits. Again, we depict an algorithm based on our novel concept and we also present simulations on our proposed circuits. Besides, the comparative analysis of our proposed compact method shows our proposed circuit outperform than existing circuit as highest improvements of proposed circuits are 33.33% for garbage output, 26.66% for quantum cost and 50% for gate count. Finally, overall significance of our proposed designs is presented in conclusion.
In recent years, reversible logic circuits have applications in the emerging field of digital signal processing, optical information processing, quantum computing and nano technology. Reversibility plays an important role when computations with minimal energy dissipation are considered. The main purpose of designing reversible logic is to decrease the number of reversible gates, garbage outputs, constant inputs, quantum cost, area, power, delay and hardware complexity of the reversible circuits. This paper reveals a comparative review on various reversible logic gates. This paper provides some reversible logic gates, which can be used in designing more complex systems having reversible circuits and can execute more complicated operations using quantum computers. Future digital technology will use reversible logic gates in order to reduce the power consumption and propagation delay as it effectively provides negligible loss of information in the circuit. Keywords: Garbage output, Power dissipation, quantum cost, Reversible Gate, Reversible logic,
Reversible computing is gaining importance in order to achieve low power consumption, high speed and packaging density in VLSI circuits. It has applications in various other fields such as quantum computing, nanotechnology, DNA computing, optical computing, cryptography and informatics. In order to achieve reliable circuits in reversible computing provision for fault tolerance is necessary. To achieve fault tolerance, the first stage is to identify occurrence of fault. To detect the occurrence, parity preserving technique has been reported in literature. This paper presents a new 4*4 parity preserving reversible logic gate PPTG (Parity Preserving Toffoli Gate) and its quantum realization. After that two new parity preserving implementations are presented in this paper. These implementations are used towards the development of fault tolerant reversible circuits. By which substitution becomes efficient and minimum in terms of constant inputs and garbage outputs. It permits us to use existing benchmarks preserving parity with only one additional circuit line.
Reversible logic is emerging as a promising computing paradigm with applications in ultralow power nanocomputing and emerging nanotechnologies such as quantum computing, quantum dot cellular automata (QCA), optical computing, etc. Reversible circuits are similar to conventional logic circuits except that they are built from reversible gates. In reversible gates, there is a unique, one-to-one mapping between the inputs and outputs, not the case with conventional logic. One of the primary motivations for adopting reversible logic lies in the fact that it can provide a logic design methodology for designing ultra-low power circuits beyond KTln2 limit for those emerging nanotechnologies in which the energy dissipated due to information destruction will be a significant factor of the overall heat dissipation. Further, logic circuits for quantum computers must be built from reversible logic components. Several important metrics need to be considered in the design of reversible circuits the importance of which needs to be discussed. Quantum computers of many qubits are extremely difficult to realize thus the number of qubits in the quantum circuits needs to be minimized. This sets the major objective of optimizing the number of ancilla inputs and the number of the garbage outputs in the reversible logic based quantum circuits. The constant input in the reversible quantum circuit is called the ancilla input, while the garbage output refers to the output which exists in the circuit just to maintain one-to-one mapping but is not a primary or a useful output. The reversible circuit has other important parameters of quantum cost and delay which need to be optimized.