by Prof. Dr. Leonhard M. Reindl, Albert-Ludwigs-Universität Freiburg
04.02.2019, 17:15 h, TF, Aquarium
Wireless sensor or actuator systems, like portable phones, remote control, ID cards, or embedded wireless sensor nodes play an ever growing role in our industrialized environment. Those systems were enabled due to the steadily decreasing power consumption of high integrated ICs. Most such systems are powered by batteries or inductive coupling. In this presentation several concepts for an alternative power supply of wireless sensor or actuator systems are discussed in detail.
Batteries, although today mostly used, suffer from a limited storage capacity, which induce a labor and sometimes cost-intensive periodic maintenance, and also a problematic ecological impact. The usable range for inductive coupling systems is restricted to a distance of about the aperture of the coupling coil. UHF systems operate in the far field and reach higher distances. Their operating range is limited by the distance where the voltage at the feeding point of the antenna becomes too low to drive the rectifier circuit. Larger read out ranges become feasible by omitting the rectifier stage. In this case we need either a passive frequency modulating device to shift the read out signal to a side band, or a resonator with a high quality factor, like a SAW, BAW, or a dielectric resonator, to store the energy until all environmental echoes are fade away. For many applications, both indoor and outdoor, energy harvesting system become feasible which convert ambient power densities like light, RF fields, local or temporal thermal gradients, or mechanical vibrations into electrical supply power for the wireless system.
All those systems strongly suffer from a lack of energy. Thus new concepts for lowering the power consumption of a wireless sensor or actuator system - by keeping their performance - remain extreme important. Hereby, a wireless wake up receiver technique is presented which operates on a current requirement as low as 3 micro A.
Several application examples of the presented systems will be given, e.g., sensors for industry 4.0, indoor position sensors, inductively transmitted power to implants, and high temperature wireless sensors.