A new XOR-based Content Addressable Memory architecture

In this paper we describe a Content Addressable Memory (CAM) architecture based on a new custom cell, called XORAM. The cell is composed by two main blocks: a 6T-SRAM, and a 4T-XOR logic gate. Each XORAM cell compares the input data on the bit line with the data stored in the 6T-SRAM cell. The output matching bit is obtained by performing a NOR operation between all bits of the XORAM cells storing the word. The proposed architecture is based on a fully-CMOS combinational logic, and it does nor require any precharge operation or control and timing logic. A compact full-custom layout has been designed for a memory organized in 18-bit words, to reduce both area and power consumption. Compared with a conventional selective precharge match-line technique, the proposed circuit occupies less area. Simulation results demonstrate that power consumption is reduced by a factor of 8.