Imprecise Minority-Based Full Adder for ‎Approximate Computing Using CNFETs

Document Type : Research Paper


1 Department of Computer Engineering, Yadegar -e- Imam Khomeini (RAH) Branch, Islamic ‎Azad University, 1815163111, Tehran, Iran.‎

2 Faculty of Computer Science and Engineering, Shahid Beheshti University, G.C., Evin ‎‎1983963113, Tehran, Iran.‎


   Nowadays, the portable multimedia electronic devices, which employ signal-processing modules, require power aware structures more than ever. For the applications associating with human senses, approximate arithmetic circuits can be considered to improve performance and power efficiency. On the other hand, scaling has led to some limitations in performance of nanoscale circuits. Accordingly, Carbon Nanotube Field Effect Transistors have gotten a widespread attention as the most appropriate replacement for MOSFETs. In this paper, an imprecise full adder cell based on CNFET minority gates is introduced. Evaluation and comparison of the minority-based and the-state-of-the-art imprecise full adders in terms of average power dissipation, delay and power delay product (PDP) are done. The error distance (ED), normalized error distance (NED) and PDP-NED product metrics are also considered for assessing the accuracy of the reviewed circuits. The HSPICE simulations, conducted using Stanford 32nm CNFET model, indicate that the minority-based design outperforms the other designs in terms of performance and error tolerance.