CIRCUIT APPLICATIONS OF CARBON NANOTUBE FETs

Carbon Nanotube FETs (CNFETs) are showing significant promise in nanoelectronics. They are one of the principle areas of research that are seen as having the capability of replacing MOSFET transistors. In fact, their performance is much better than MOSFETs below 10nm [1], with the operation frequencies of CNFET devices being up to1000 times greater. This project investigates various properties of CNFETs and particularly their application in digital logic design [2]. Various logic gates were built using CNFETs, and their properties are studied. Finally, a 4-bit Ripple Carry Adder (RCA) was built using the gates and the power dissipation and propagation times are observed. The gates were implemented using the generic Pull-Up-and Pull-Down-Network with a 0.5V power supply. Parasitic capacitances of the gates were estimated and included in the models. The gates were then simulated. In particular, the NAND, XOR and INV power and delay characteristics were observed, and the Power Delay Product (PDP) calculated as in Table 1. The gates above were used to build a Full Adder (FA). This was done using 2 XOR gates and 3 NAND gates, bringing the total number of transistors to 36. This design was chosen because it ensured that no more that 2 transistors were in series and was therefore a faster circuit. It was also more versatile than other designs. The FA simulation output is shown in Fig 1. The FA was then cascaded to create a 4-bit RCA, which also had cascade capabilities. This circuit was simulated, and the results are displayed on Fig