True Three-Valued Ternary Content Addressable Memory Cell Based on Ambipolar Carbon Nanotube Transistors

摘要

Carbon nanotube-based transistors (CNTFETs) have been shown to exhibit ambipolar field-effect transistor behavior, allowing circuit designers to easily choose between n- and p-conduction channels by applying correct voltages at a polarity gate. In this paper, we explore this ambipolar behavior of the CNTFET to design both binary and ternary content addressable memory (AM) cells. Using SPICE simulation, we show the designs of a traditional ternary CAM (TCAM) and a true three-valued TCAM (T3CAM) functionality of the proposed cells and show that the ambipolar design can lead to a savings of up to 31% in terms of transistor count over a traditional design. We also explore issues related to matchline leakage, cell stability and design in the presence of metallic tubes.