A ReRAM-Based 4T2R Nonvolatile TCAM Using RC-Filtered Stress-Decoupled Scheme for Frequent-OFF Instant-ON Search Engines Used in IoT and Big-Data Processing

Abstract

This paper outlines the RC-filtered stress-decoupled (RCSD) 4T2R nonvolatile TCAM (nvTCAM) with the following benefits: 1) reduced NVM-stress; 2) reduced ML parasitic load; and 3) suppression of match-line (ML) leakage current from match cells. The RCSD-4T2R cell achieves a 6 $\times $ reduction in NVM-stress, a 2 $\times $ increase in maximum wordlength, and a 2 $\times $ reduction in search delay. In this paper, we also outline two search schemes, referred to as dynamic source-line pulse controlled (DSL-PC) search and dataline-pulse controlled (DL-PC) search, which were developed specifically for the RCSD-4T2R nvTCAM. We fabricated a 128 $\times $ 32 b RCSD-4T2R nvTCAM macro with HfO ReRAM using a 180 nm CMOS process. Using the DSL-PC and DL-PC schemes, the measured search delay of the RCSD-4T2R nvTCAM macro was 1.2 ns under typical VDD.