Defence of doctoral thesis in the field of Micro- and Nanoelectronic Circuit Design, M.Sc.(Tech.) Tuomas Haapala

The title of the thesis is Microwatt integrated radio transceiver circuits for aggressively duty-cycled wireless networks

M.Sc.(Tech.) Tuomas Haapala will defend the thesis " Microwatt integrated radio transceiver circuits for aggressively duty-cycled wireless networks " on 10 May 2021 at 12 in Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering.

Opponent: Dr. Alison Burdett, Sensium Healthcare, Oxford, UK
Supervisor: Prof. Kari Halonen, Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering

The public defense will be organized via remote technology. Follow defence: https://aalto.zoom.us/j/63278674941
Zoom Quick Guide: https://www.aalto.fi/en/services/zoom-quick-guide

Thesis available for public display at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/

Doctoral theses in the School of Electrical Engineering: https://aaltodoc.aalto.fi/handle/123456789/53

Press release:

A smart phone, smoke detector and remote control operate wirelessly. To enable this wireless operation, they are commonly powered by batteries.

Instead of batteries, a mobile electronic device may also be powered by an energy harvester such as a photovoltaic cell. The lack of batteries saves material and maintenance costs as well as the environment since used batteries become toxic waste. However, a coin-battery-sized photovoltaic cell can only generate several microwatts of power under office illumination. Consequently, the power consumption of a wireless device must be lowered to microwatt level to make it energy-autonomous.

A key obstacle for achieving microwatt power consumption is caused by a mobile device’s radio transceiver that commonly dominates the power budget. The average power consumption of a radio circuit can be lowered considerably by aggressive duty-cycling, that is by keeping the radio circuit in sleep for long periods of time. However, an aggressively duty-cycled radio circuit must be powered up frequently. The power-up events consume energy and the radio transceiver may have to re-acquire the wireless network after each power up. Techniques that lower the power-up time require power themselves and might affect the quality of the transmitted radio signal.

This work presents a microwatt impulse radio transmitter whose operation is extremely duty-cycled. The operation principle of the transmitter resembles that of domino blocks. A chain of domino blocks can be set falling by a simple push, much like the simple trigger required by the transmitter. The presented radio transmitter features high programmability, radio signal quality and stable operation over temperature. In addition, this work presents a compensation method that allows sleeping radio circuits to reacquire the wireless network quickly. The compensation method removes the varying frequency offset of a radio circuit affected by both temperature and aging. Consequently, the required network acquisition time is considerably lowered.

The aggressively duty-cycled radio circuits presented in this dissertation can be deployed in microwatt energy-harvesting wireless devices. This kind of maintenance-free and environmentally friendly devices can be utilized e.g. in smart environments and logistics chains as identification tags, various sensors (temperature, proximity, strain) and burglar alarms.

Contact information of doctoral candidate: