Synchronous circuit design with beyond-CMOS magnetoelectric spin-orbit devices toward 100-mV logic

Abstract

The supply voltage scaling has become increasingly challenging in the advanced CMOS technology due to the threshold voltage requirement for transistor OFF leakage, limiting the system energy efficiency. Spintronic logic utilizes the physical quantity of magnetization or spin as a computation variable, offering new design paradigms in terms of ultralow voltage operation and nonvolatility, but suffering from switching inefficiency of the charge-to-spin conversion. The magnetoelectric spin-orbit (MESO) device has been proposed as a new alternative logic device candidate to solve these issues by magnetoelectric transduction using a novel multiferroic oxide [both ferroelectric (FE) and antiferromagnetic], a ferromagnet and a spin injection layer. It enables a path toward 10-100 × switching energy reduction compared to CMOS inverter in 2018 node, due to the device and material innovations of a novel switching mechanism. In this paper, in order to build a MESO logic family for new circuit and architecture exploration, we propose for the first time the fundamental building blocks such as MESO sequential and combinatorial circuits for the synchronous logic operation. We employ a transistor sharing and a novel multiphase clocking scheme to address the circuit design issues such as clock control, directionality of state propagation, and power gating and enable the design exploration for MESO digital logic. Based on the proposed circuit techniques, we demonstrate these MESO logic functions operating at a supply voltage of 100 mV and a clock period of 1.2 ns with 320-ac FE polarization through the circuit simulations.