Developing TEI-Aware Ultralow-Power SoC Platforms for IoT End Nodes

Ranging from circuit-level characterization to designing a platform architecture, developing a design automation tool, and fabricating a System on Chip (SoC), this article deals with the entire development process for ultralow-power (ULP) SoCs for Internet-of-Things (IoT) end nodes. More precisely, this article first focuses on the unique characteristics of the ULP circuits, the temperature effect inversion (TEI), i.e., the delay of the ULP circuits decreases with increasing temperature. Existing TEI-aware low-power (TEI-LP) techniques have incredible potential to further reduce the power consumption of conventional ULP SoCs, but there is a critical limitation to be widely adopted in real SoCs. To address this limitation and realize the ULP SoCs that can fully benefit from the TEI-LP techniques, this article proposes a new TEI-inspired SoC platform (TIP) architecture. On top of that, taking into account that the highly complex, time consuming, and labor-intensive development process of these ULP SoCs may hinder their widespread use for IoT end nodes, this article presents a new electronic design automation tool to accelerate ULP SoC development, RISC-V express (RVX). Finally, by using the RVX, this article introduces a TIP prototyping chip fabricated in 28-nm FD-SOI technology. This chip demonstrates that power savings of up to 35% can be achieved by lowering the supply voltage from 0.54 to 0.48 V at 25 °C and 0.44 V at 80 °C while continuing to operate at a target 50-MHz clock frequency.