Hybrid CMOS-CNFET based NP dynamic Carry Look Ahead Adder
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Advanced electronic device technologies require a faster operation and smaller average power consumption, which are the most important parameters in very large scale integrated circuit design. The conventional Complementary Metal-Oxide Semiconductor (CMOS) technology is limited by the threshold voltage and subthreshold leakage problems in scaling of devices. This leads to failure in adapting it to sub-micron and nanotechnologies. The carbon nanotube (CNT) technology overcomes the threshold voltage and subthreshold leakage problems despite reduction in size. The CNT based technology develops the most promising devices among emerging technologies because it has most of the desired features. Carbon Nanotube Field Effect Transistors (CNFETs) are the novel devices that are expected to sustain the transistor scalability while increasing its performance. Recently, there have been tremendous advances in CNT technology for nanoelectronics applications. CNFETs avoid most of the fundamental limitations and offer several advantages compared to silicon-based technology. Though CNT evolves as a better option to overcome some of the bulk CMOS problems, the CNT itself still immersed with setbacks. The fabrication of carbon nanotube at very large digital circuits on a single substrate is difficult to achieve. Therefore, a hybrid NP dynamic Carry Look Ahead Adder (CLA) is designed using p-CNFET and n-MOS transistors. Here, the performance of CLA is evaluated in 8-bit, 16-bit, 32-bit and 64-bit stages with the following four different implementations: silicon MOSFET (Si-MOSFET) domino logic, Si-MOSFET NP dynamic CMOS, carbon nanotube MOSFET (CN-MOSFET) domino logic, and CN-MOSFET NP dynamic CMOS. Finally, a Hybrid CMOS-CNFET based 64-bit NP dynamic CLA is evaluated based on HSPICE simulation in 32nm technology, which effectively suppresses power dissipation without an increase in propagation delay.
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