Run-Time Measurement of Harvested Energy for Autarkic Sensor Operation

Abstract

Harvesting energy from the environment in order to provide sensors with autarky entails many challenges. Foremost is the ability to match the energy uptake and storage, so that the maximal yield possible is attained. This involves sophisticated analogue circuitry, to continuously match the harvesting element. It also involves digital logic exploiting features of the analogue modules, to quantify and control the energy budget at run-time. The overall goal was to minimize periods of energy starvation, as well as periods where harvesting is not possible, due to limited storage capacity. The present paper introduces an on-chip vibration harvesting unit fabricated with the 0.35um AMS CMOS technology, feeding sensors in the presence of extremely volatile energy environments. It demonstrates both analogue and digital parts integrated on a 3.06mm ² chip, as well as their coordination, targeting autarkic sensor operation.