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This study proposes an 18‐transistor full adder (FA) cell based on the full swing hybrid logic style. It has a first stage comprising the XOR‐XNOR module followed by pass transistors and inverters to generate the sum and carry outputs. The performance evaluation of the proposed FA cell has been carried out using an HSPICE simulator at the 16 nm process node by comparing it with eight existing FAs over the supply voltage ranging from 0.4 to 1.0 V. The proposed adder achieved 34.77% improvement in propagation delay, 48.8% improvement in average power and 66.58% improvement in Power Delay Product compared to the conventional CMOS Mirror adder while operating at 0.8 V. Moreover, its performance metrics are also better than those of other latest existing adder cells. Hence, the proposed FA is suitable for modern high performance digital processors.

Full Adder (FA) circuits are integral components in the design of Arithmetic Logic Units (ALUs) of modern computing systems. Recently, there have been massive research interests in this area due to the growing need for low-power and high-performance computing systems. Researchers have proposed a variety of FA cells with diverse design techniques, each having its pros and cons. As a result, a systematic method for performance comparison of FA cells using a common simulation platform has become necessary. In this work, we present an extensive study of FA cells. We have compared the performance of thirty-three (33) existing 1-bit FA cells. The drive powers of these FA cells have been compared by applying a variety of load conditions. In addition, the 1-bit FA cells have been extended to 32-bit structures to test their scalability and to investigate their performance in wide-word structures. We have determined that twenty-one (21) of the thirty-three (33) FA cells cannot operate in a 32-bit structure, even though some of them exhibit excellent performance as a 1-bit cell. The main finding of this research is that the single-bit performance parameters of FA cells should not be considered as the main basis for performance comparison. Any FA cell should be analyzed in a multi-bit structure to determine its practical effectiveness. Article Highlights Hybrid full adders offer better performance than single logic full adders Many existing full adder cells are not scalable Conventional Mirror CMOS full adder offers better performance than many recent full adders in wide adder structure

Comparator is a basic arithmetic component in a digital system and adders are the basic block of processor unit, the performance of adder will improve the system performance. The proposed 11T adder comparator is consists of three main components, namely XOR, inverter, and MUX logic. The circuit is designed and implemented based on top-down approach with 11 transistors. The proposed cell can be used at higher temperature with minimal power loss. It also gives faster response for the carry output. The proposed comparator circuit shows 63.80% improvement in power consumption than other circuits.

Complementary metal oxide semiconductor (CMOS) is a low-power technology typically used in the efficient implementation of digital circuits. However, at nanodimensions, CMOS has problems due to its short channel effects and subthreshold leakage currents. These drawbacks can be overcome with quantum-dot cellular automata (QCA) which is one of the fastest nanotechnologies operated at THz rate. Thus, all digital circuits can now be implemented by QCA at the required nanoscale. This paper proposes a novel, energy-efficient and area-optimized 1-bit full adder design using QCA which provides efficient clocking, reduced cell count and reduced energy dissipation. The proposed design utilizes only 26 quantum cells in 0.02 µm 2 area and has a reduction of 8% in number of cells, 75% in delay and 4% in energy dissipation at 1 K compared to the existing works. This innovative full adder design is used to implement a 4 × 4 Baugh–Wooley multiplier. The simulation results of the multiplier observed on QCADesigner 2.0.3 tool validate that the Baugh–Wooley multiplier designed with the novel 1-bit full adder yields better performance in terms of 9% reduction in area, 17.4% reduction in quantum cells used and reduced power dissipation of 2.44nW.

The static power consumption is an important parameter concern in IC design due to t for a higher integration numbers of transistor to achieve greater performance in a single chip. Leakage current is the main issues for static power dissipation in standby mode as the size of transistor been scale. Therefore, the subthreshold leakage current rises due to threshold voltage scaling and gate leakage current increases due to scale down of oxide thickness. In this paper, a Variable Body Biasing (VBB) technique was applied to reduce static power consumption in VLSI design. The VBB technique used a DC bias at body terminal to control the threshold voltage efficiently. The Synopsys Custom Designer EDA tools in 90nm MOSFET technology was used to design a 1-bit full adder with VBB technique in full custom methodology. The simulation of 1-bit full adder was carried out with operation voltage   supply was compared in conventional technique and VBB technique. The results achieved the reduction in term of peak power,   and average power,   in static CMOS 1-bit full adder compared with conventional bias and VBB technique.

In this paper, a hybrid 1-bit adder and 1-bit Subtractor designs are implemented. The hybrid adder circuit is constructed using CMOS (complementary metal oxide semiconductor) logic along with pass transistor logic. The design can be extended 16 and 32 bits lately. The proposed full adder circuit is compared with the existing conventional adders in terms of power, delay and area in order to obtain a better circuit that serves the present day needs of people. The existing 1-bit hybrid adder uses EXNOR logic combined with the transmission gate logic. For a supply voltage of 1.8V the average power consumption (4.1563 µW) which is extremely low with moderately low delay (224 ps) resulting because of the deliberate incorporation of very weak CMOS inverters coupled with strong transmission gates. At 1.2V supply the power and delay were recorded to be 1.17664 µW and 91.3 ps. The design was implemented using 1-bit which can also be extended into a 32-bit design later. The designed implementation offers a better performance in terms of power and speed compared to the existing full adder design styles. The circuits were implemented in DSCH2 and Microwind tools respectively. The parameters such as power, delay, layout area and speed of the proposed circuit design is compared with pass transistor logic, adiabatic logic, transmission gate adder and so on. The circuit is also designed with a decrease in transistors in order to get the better results. Full Subtractor, a combinational digital circuit which performs 1-bit subtraction with borrow in is designed as a part of this project. The main aim behind this part of the project is to design a 1-bit full Subtractor using CMOS technology with reduced number of transistors and hence the efficiency in terms of area, power and speed have been calculated is designed using 8,10,15and 16 transistors. The parameters were calculated in each case and the results have been tabulated.