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        1 - Low Latency and Power Efficient Reversible Full Adder based on Toffoli Gates
        Seyedeh Fatemeh Deymad Nabiollah Shiri Farshad Pesaran
        The reversible circuits are useful in energy-saving applications because of their unique features. Hence, using 32 nm carbon nanotube field-effect transistor (CNTFET) technology and relying on Toffoli's reversible gates, a new full adder (FA) circuit is presented. The p More
        The reversible circuits are useful in energy-saving applications because of their unique features. Hence, using 32 nm carbon nanotube field-effect transistor (CNTFET) technology and relying on Toffoli's reversible gates, a new full adder (FA) circuit is presented. The proposed circuit has 4 basic Toffoli gates and 18 transistors. 3 of the 4 gates have the same transistor schematic with a constant-ON transistor, but the remaining gate has only two transistors. The proposed circuit has 3 constant inputs and 4 garbage outputs. As a new method, in the proposed circuit, only one type of reversible gate is used. The results show the superiority of the proposed FA in terms of power consumption and energy dissipation. By implementing the proposed FA and other circuits in a 4-bit and 8-bit ripple carry adder (RCA), the proposed circuit shows improvements by 6.83% and 11.25% in terms of power and energy, respectively, compared to the main competitor. Also, in an 8-bit RCA, the proposed FA has a 2% saving compared to the nearest competitor and 27% compared to the worst circuit in terms of the power-delay-area-product (PDAP). These results show the designed FA as a favorable option for complex structures with high-order bits. Manuscript profile
      • Open Access Article

        2 - A Multiplier-Less Discrete Cosine Transform Architecture Using a Majority Logic-Based Approximate Full Adder
        Elham Esmaeili Farshad Pesaran Nabiollah Shiri
        This paper proposes a new approximate full adder (FA) based on the majority logic (ML) concept. The fundamental structure of the ML concept is a 3-input majority voter and is widely utilized in digital arithmetic cells. The ML-based proposed FA works at low power, small More
        This paper proposes a new approximate full adder (FA) based on the majority logic (ML) concept. The fundamental structure of the ML concept is a 3-input majority voter and is widely utilized in digital arithmetic cells. The ML-based proposed FA works at low power, small delay, and low power-delay-product (PDP). The carbon nanotube field-effect transistor (CNTFET) technology lowers the FA power, while the gate diffusion input (GDI) technique is used as the main technique. The swing issue of the GDI technique is resolved by the dynamic threshold (DT) technique. Compared with its exact circuit, the proposed FA saves 2 majority gates, 3 inverters, and a 4.02 ns delay. In the proposed FA, the PDP is improved by 53.73%. The product of the PDP and the normalized mean error distance (NMED) is called PDPE, and in the presented FA, it is reduced by 9.50%. Moreover, the proposed FA is embedded into a multiplier-less discrete cosine transform (DCT) design, which is an appropriate circuit for very large-scale integration (VLSI) systems. The 8-input DCT architecture consumed 2.2321 mW of power for each DCT operation. Also, the circuit has better performance in terms of PDP-area-product (PDAP). The results of DCT implementations confirm the efficiency of the FA. Manuscript profile
      • Open Access Article

        3 - Low-power and reliable approximate subtractors for image processing applications
        Fatemeh Pooladi Farshad Pesaran Nabiollah Shiri
        In this paper, two new approximate subtractors are presented. The proposed circuits are implemented based on gate diffusion input (GDI) and dynamic threshold (DT) techniques and are named Proposed-1 and Proposed-2. The Proposed-1 subtractor has 10 transistors, while Pro More
        In this paper, two new approximate subtractors are presented. The proposed circuits are implemented based on gate diffusion input (GDI) and dynamic threshold (DT) techniques and are named Proposed-1 and Proposed-2. The Proposed-1 subtractor has 10 transistors, while Proposed-2 has 12 transistors. Subtractors are implemented by 32 nm carbon nanotube field effect transistor (CNTFET) technology. Various studies have been performed and show the high efficiency and performance of the circuits in different conditions without reducing their output voltage, which is caused by the use of DT in their implementation. The proposed circuits use XOR and NOT gates, both of which have 4 out of 8 error states. The presented subtractors can be implemented in an unsigned non-recovery divider with different structures including vertical, horizontal, square and triangular, etc., and finally, they can be used in image processing applications to detect the difference between two images, either medical or standard images. The simulation results show the better performance of the proposed circuits, Proposed-1 and Proposed-2 save PDP of 88.36% and 83.25%, respectively. Manuscript profile