A PCM-based TCAM cell using NDR

This paper presents a new design of a ternary content addressable memory (TCAM) cell. This design exploits two emerging technology devices: a phase change memory (PCM) as storage element and a negative differential resistance (NDR) device as control element. The PCM stores a multi-value resistance to account for the ternary nature of the equality function to be performed in a TCAM. The CMOS-NDR device uses a macroscopic model made of three transistors to exhibit a very high peak-to-valley current ratio, a single symmetric peak and excellent switching speed. The CMOS-NDR device is embedded in the cell such that specific operational points are placed on the I-V curve for generating the match/mismatch outcome. A common-source amplifier with source degeneration is used for decoding the PCM. Extensive simulation results at nanoscale feature sizes (45, 32 and 22 nm) are presented. These results show that the proposed TCAM cell outperforms a previously presented non-volatile TCAM cell based on MTJ in terms of power dissipation and power delay product (PDP).