A FeFET-Based Hybrid Memory Accessible by Content and by Address

Emerging nonvolatile memory technologies are attracting interest from the system design level to implement alternatives to conventional von-Neumann computing architectures. In particular, the hafnium oxide-based ferroelectric (FE) memory technology is fully CMOS-compatible and has already been used for logic-in-memory architectures or compact ternary content addressable memory (TCAM) cells. These enable the tight combination of different functionalities in the same circuit to reduce implementation area and energy consumption. In this article, we propose a new hybrid memory circuit that combines TCAM and normal memory capability: the Ternary Content addressable and MEMory (TC-MEM). A 1-bit TC-MEM circuit is proposed and discussed in detail, both as a concept and through its implementation in a 28-nm ferroelectric field-effect transistor (FeFET) technology. Measurement results demonstrate the circuit functionality. We also discuss how to scale it to multibit circuits, as well as its use both as a TCAM and as a normal memory allowing the implementation of reversible functions using one memory table instead of two memory tables, and in-memory-computing concepts.