A comparative study of STT-MTJ based non-volatile flip-flops

Abstract

In this paper, we categorize STT-MTJ based non-volatile flip-flops (NV-FF) into two basic structures: merged latch and sensing circuit (MLS) structure and separated latch and sensing circuit (SLS) structure. We also analyze the two structures with various types of sensing and write circuits. HSPICE simulation results using the industry-compatible 45-nm model parameter shows the SLS structure has better performance according to D-Q delay, PDP, and sensing current than the MLS structure because the SLS structure can optimize the FF operation and the sensing operation independently. Among various types of sensing circuit, the cross coupled inverter based sensing circuit including two MTJs and the single ended sensing circuit including two MTJs show better performances on low sensing current and high yield.