  Traditional silicon binary circuits continue to face challenges such as high
leakage power dissipation and large area of interconnections. Multiple-Valued
Logic (MVL) and nano devices are two feasible solutions to overcome these
problems. In this paper, a novel method is presented to design ternary logic
circuits based on Carbon Nanotube Field Effect Transistors (CNFETs). The
proposed designs use the unique properties of CNFETs, for example, adjusting
the Carbon Nanontube (CNT) diameters to have the desired threshold voltage and
have the same mobility of P-FET and N-FET transistors. Each of our designed
logic circuits implements a logic function and its complementary via a control
signal. Also, these circuits have a high impedance state which saves power
while the circuits are not in use. In an effort to show a more detailed
application of our approach, we design a 2-digit adder-subtractor circuit. We
simulate the proposed ternary circuits using HSPICE via standard 32nm CNFET
technology. The simulation results indicate the correct operation of the
designs under different process, voltage and temperature (PVT) variations.
Moreover, a power efficient ternary logic ALU has been design based on the
proposed gates.
