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A new 1-bit digital comparator named 14T-SR-GDI is presented with gate-diffusion-input (GDI) and single-swing-restoration (SR) techniques to attain internal gates with high driving capability. The comparator has 14 transistors which produce full-swing outputs with low power consumption. In the 14T-SR-GDI, boosted inner signals are used to activate the output gates which result in a high-speed circuit with effective scalability and the enhanced driving capability for multi-bit structures. The comparator has a low power delay product (PDP) due to the small numbers of internal nodes and capacitances and efficient power-ground-free gates. The 14T-SR-GDI comparator, fully SR-GDI-based AND, and OR gates, construct a new tree structure for multi-bit magnitude comparators including 2-bit, 4-bit, 8-bit, and 16-bit comparators. The proposed 1-bit comparator is used in image processing for difference detection, and its efficiency is proved by image quality parameters. The post-layout simulations are performed for the 1-bit to 16-bit structures under TSMC 90 nm technology. The extracted results express a PDP with an average difference of 9.59% between the regular and post-layout modes. Also, the proposed 16-bit comparator is embedded in a pad with a total area of 4331.25 μm2. The designed magnitude comparators are key components in digital signal processors (DSPs). [ABSTRACT FROM AUTHOR]

Size reduction in complementary metal–oxide–semiconductor integrated circuits (ICs) is a challenge. Carbon nanotube field effect transistor (CNTFET) technology with advantages such as low power, high mobility, and ballistic transmissions is an alternative. Based on the standard 32 nm CNTFET technology, a new 23-transistor full adder cell is proposed with combining advantages of gate diffusion input and transmission gate techniques, which are low power and full swing. Owing to small number of transistors and internal nodes, the delay time and activity factor decreased to 13.5τ. Simulations of critical parameters variations like VDD, temperature, and fan-out expose better performance of the proposed cell. Investigating the process voltage temperature with Monte Carlo simulation verified better stability, immunity, and tolerability of the cell in comparison with well-known full adder cells. Suggested full adder cell was implemented in 4:2 compressor with 9.0298 fJ of power delay product and minimum area occupation among the references. Based on real chip measurements, total die area occupation for proposed full adder and compressor is 0.505 µm2 and 1.092 µm2, respectively. Proposed circuits were applied to an 8-bit subtractor for orthopantomogram image processing to detect tooth core build up and restored with dental filling in order to maintain a crown restoration. Merits of proposed circuits both in IC design and image processing make these circuits suitable choice for bioelectronics chips. [ABSTRACT FROM AUTHOR]

Gate diffusion input (GDI) method using a simple cell makes it possible to design low-power logic gates with reduced chip area and less complexity. In this work, a novel design of single-bit optimized reversible logic-based magnitude arithmetic unit (RMAU) circuit, using appropriate standard reversible gates with carbon nanotube (CNT) field-effect transistors (CNTFETs), based on modified-GDI (m-GDI) method for nanoscales is presented. In order to optimize the performance of the proposed circuit, and to achieve minimum power consumption and propagation delay, transistor sizes are adjusted using the non-dominated sorting genetic algorithm II (NSGA-II) in MATLAB tool. The simulation results show improvement in evaluating the figure of merits in worst-case delay and power consumption of the proposed optimized arithmetic unit, in comparison with a non-optimized RMAU circuit using a similar design method but counterpart structures. The effects of different process parameters (such as the diameter of CNTs) and voltage and temperature (PVT) variations are extensively evaluated by the Monte Carlo procedure in standard 32 nm technology utilizing the Synopsys HSPICE simulator. According to the outcomes obtained, the proposed optimized RMAU circuit is robust against PVT variations and noise-tolerable criterions, compared to those competitors with similar design in non-optimized conditions. The proposed optimized and non-optimized circuits were used in image processing as real environment assessments, and results depicted their excellent ability in being implemented in various large reversible-based applications, such as future generations of FPGA chips and CNTFET-based computers. [ABSTRACT FROM AUTHOR]