Power-shaping configurable microprocessors for IoT devices

Abstract

The "Internet of Things" implies a pervasive diffusion of "IoT processors": small mixed-signal ICs, containing specific sensing/actuating logic coupled to embedded microprocessor core(s) for control, communication, and information processing. IoT processors must be small, low cost, low power, and highly reliable in order to be embedded in remote, often inaccessible locations. Most of all, they must sustain time-varying computation loads, dictated by real time events in the environment they are embedded in. This chapter introduces design strategies for "Power-Shaping Microprocessor Systems": with relatively limited design overhead, processor systems can be composed by independent, asynchronous clock, voltage and substrate bias islands. Depending on the relative workload of each section, each component in the processor system can be dynamically tuned to the smallest consumption level that still meets real time specification. Such option offers performance boost in the range of 30%, and decrease in power consumption in the range of 70%, with area overheads in the range of 5-10% depending on the design environment. It also enables a mitigation of a rough factor of 5 in current peaks/gradients on the supply lines of each IC. This result is highly relevant, since current gradients are a significant cause of unreliability on CMOS circuits, especially in mixed analog/digital environments such as IoT processors.