Abstract:In this paper two ultra high speed carbon nanotube FullAdder cells are presented. First design uses two transistors, two resistors and seven capacitors and the second one uses four transistors and seven capacitors. The first design is faster and the second one consumes less power. Simulation results illustrate significant improvement in terms of speed and Power-Delay Product (PDP).

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Abstract-Binary logic circuits are limited by the requirement of interconnections. A feasible solution is to transmit more information over a signal line and utilizing multiple-valued logic (MVL). This paper presents a novel high performance quaternary full adder cell based on carbon nanotube field effect transistor (CNTFET). The proposed Quaternary full adder is designed in multiple valued voltage mode. CNTFET is a promising candidate for replacing MOSFET with some useful properties, such as the capability of having the desired threshold voltage by regulating the diameters of the nanotubes, which make them very appropriate for voltage mode multiple threshold circuits design. The proposed circuit is examined, using Synopsys HSPICE with the standard 32 nm CNTFET technology with different temperatures and supply voltages.

Recently multiple valued logic has attracted the attention of digital system designers. Scalable threshold voltage values of carbon nanotube field-effect transistors (CNFETs) can easily be utilised for multiple-V t circuit designs. In this study, a novel energy-efficient method for designing one-digit adder is proposed. The suggested design employ ternary multiplexers to select successor and predecessor of input trits for the output node values. This study describes the novel ternary multiplexer, successor and predecessor cells. The proposed full adder design is evaluated using HSPICE simulation with the standard 32 nm CNFET technology under different operational conditions, including different supply voltages, variation of output load and various operational temperatures. In addition, the sensitivity to process variations of the design is investigated. Finally, the proposed designs are compared with state-of-the-art ternary circuits and based on the simulation results, the proposed full adder cell decreases the power consumption up to 2.3 times lower than the best existing techniques in the literature.

Carbon Nano-Tube Field Effect Transistors (CNTFETs) are being widely studied as possible successors to silicon MOSFETs. Using current mode has many advantages such as performing sum operation by means of a simple wired connection. Also, direction of the current can be used to exhibit the sign of digits. It is expected that the advantages of current mode approaches will become even more important with increased speed requirements and decreased supply voltage. In this paper, we present five new circuit designs for differential absolute value in current mode logic which have been simulated by CNTFET model. The considered base current for this model is 2 µA and supply voltage is 0.9 V. In all of our designs we used N-type CNTFET current mirrors which operate as truncated difference circuits. The operation of Differential Absolute Value circuit calculates the difference between two input currents and our circuit designs are operate in 8 logic levels. The most important obstruction to reception of any such technology is due to encoding more than two levels of logic in the available room temperature for voltage swing is decreasedThe possible approach to solve this problem is to use the current mode techniques that use current as a signal carrier, either alone or in combination with voltage. Recent experiences demonstrate that due to design simplicity and larger dynamic range, current mode approach is becoming attractive for the performing MVL function especially when the radix is larger than 3 and it can be also applied for higher radix MVL circuit design successfully [2,3,6]. Multi-valued current-mode circuits could be useful only if they can be implemented with today and tomorrow technologies [7].For many years MOSFET has been used as a basic element of circuit designing. As the miniaturization of silicon based circuits reaches its physical limitations, molecular devices are becoming hopeful alternatives to the existing silicon technology

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