Analog Content Addressable Memory using Ferroelectric: A Case Study of Search-in-Memory

Abstract

Non-volatile (NV) devices are actively considered for compact and high performance memory architectures, especially in-memory computing (IMC) designs where processing and memory elements are co-located to address the memory wall issues for data-intensive applications. Content addressable memories (CAMs) are a form of IMC that compares the input query data against the stored data in parallel, and outputs the comparison result in terms of match or mismatch. Numerous CAMs have been proposed based on NV devices and demonstrate superior area, energy and performance metrics over the CMOS based conventional ones. Unlike the prior works that exploit the NV devices in the digital domain, in this paper, we proposed an analog CAM design, which utilizes the analog characteristics of Ferroelectrics field effect transistor (FeFET) to achieve a denser storage and search operations in analog domain. We illustrate our proposed analog CAM through a device-circuit co-design approach, and validate the 3-bit storage and search capability of the proposed design. The scalability of the proposed design is also examined. Evaluation results suggests that our analog CAM can achieve 22.4 × higher memory density, and 8.6 × higher energy efficiency compared with the conventional CMOS based design.