Computing-in-Memory With Enhanced STT-MRAM Readout Margin

This article presents a spin transfer torque magnetic random access memory (STT-MRAM) in-memory multiplication structure based on enhanced readout margin through capacitor discharge and a positive feedback structure. On this basis, a computing-in-memory (CIM) macro for multiply accumulate (MAC) operations is designed. Compared with the conventional scheme, the multiplication output voltage margin (voltage difference of different calculation results) of this scheme is increased up to
$6.5\times $
. The energy consumption of performing a 1-bit and 2-bit multiplication is only 81 fJ, and the energy efficiency of the MAC operation containing four accumulations (1bIN-2bW-4Acc) is about 18.6 TOPS/W.