In-Memory Computing With Double Word Lines and Three Read Ports for Four Operands

Abstract

The von Neumann architecture is approaching its limits in terms of scalability and power consumption. In-memory computation is a possible approach to mitigate this limitation. This brief proposes a configurable 8T static random access memory (SRAM) cell with double word lines and three read ports for in-memory computing. In addition to the normal SRAM function, XOR/XNOR and compound Boolean logic operations of three or four operands, such as AND-OR, AND-OR-INVERT, OR-AND, and OR-AND-INVERT, can be performed in one cycle by fully utilizing the three read ports to obtain 13.2-fJ/bit consumption at 0.6 V. The logic operation frequency is 793 MHz at 1.2 V. The proposed SRAM effectively resolves the bottleneck of the existing in-memory computation schemes that only support compound Boolean logic operations with more than two cycles. In addition, the proposed SRAM array scheme can be configured and used as a binary content-addressable memory or a ternary content-addressable memory for searching operations; it achieves 0.24 fJ/search/bit at 0.6 V in the worst case. At 1.2 V, the searching frequency is up to 813 MHz when searching 128 bits with 65-nm technology.