Exploring Ultra Low-Power on-Chip Clocking Using Functionality Enhanced Spin-Torque Switches

Abstract

Emerging spin-torque (ST) phenomena may lead to ultra-low-voltage, high-speed nano-magnetic switches. Such current-based-switches can be attractive for designing low swing global-interconnects, like, clocking-networks and databuses. In this work we present the basic idea of using such ST-switches for low-power on-chip clocking. For clockingnetworks, Spin-Hall-Effect (SHE) can be used to produce an assist-field for fast ST-switching using global-mesh-clock with less than 100mV swing. The ST-switch acts as a compact-latch, written by ultra-low-voltage input-pulses. The data is read using a high-resistance tunnel-junction. The clock-driven SHE write-assist can be shared among large number of ST-latches, thereby reducing the load-capacitance for clock-distribution. The SHE assist can be activated by a low-swing clock (~150mV) and hence can facilitate ultra-low voltage clock-distribution. Owing to reduced clock-load and low-voltage operation, the proposed scheme can achieve 97% low-power for on-chip clocking as compared to the state of the art CMOS design. Rigorous device-circuit simulations and system-level modelling for the proposed scheme will be addressed in future.