Energy-performance Characterization of CMOS/Magnetic Tunnel Junction (MTJ) Hybrid Logic Circuits

TitleEnergy-performance Characterization of CMOS/Magnetic Tunnel Junction (MTJ) Hybrid Logic Circuits
Publication TypeThesis
Year of Publication2011
AuthorsRen, F
Academic DepartmentElectrical Engineering
DegreeMaster of Science
Date PublishedJan. 2011
UniversityUniversity of California, Los Angeles
CityLos Angeles
Thesis TypeM.S. Thesis
Keywords (or New Research Field)psclab

Magnetic Tunnel Junction (MTJ) devices are CMOS compatible with high stability, high reliability and non-volatility. All these features are promising for building non-volatile CMOS/MTJ hybrid logic circuits that do not consume off-state leakage current and that supports ultra-low-power operation. However, most existing proposals for this purpose so far lack an energy-performance analysis and a comparison to CMOS circuits. In this work, we analyze and compare the energy-performance characteristics of a wide range of CMOS/MTJ hybrid circuits over the device, circuit and architectural levels. This will include device switching energies, logic-in-memory MTJ (LIM-MTJ) logic circuit, two MTJ reading circuits and two CMOS/MTJ hybrid lookup table (LUT) architectures. Our analysis shows that the existing LIM-MTJ logic style has no advantage in energy-performance over its equivalent CMOS design, and that with the switching energy of MTJ considered, the CMOS/MTJ hybrid circuit requiring frequent MTJ switching is hardly energy efficient. Our simulation results also show that the cross-coupled inverter based MTJ reading circuit has 4 times greater performance and 30 times lower energy than the current-mirror sense amplifier based reading circuit. It is also shown that the proposed CMOS/MTJ hybrid LUT based logic architecture, which requires no MTJ switching during logic operations, is able to incorporate the non-volatility of the MTJ to alleviate the leakage problem of CMOS, and to thereby supports ultra-low power operation in advanced technology nodes (32-nm and beyond).

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