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PARTLY DIGITAL - ONLY FOR INVITEES (1,5 m) : PhD Defence Amir Saifullah | Voltage boosting amplifier techniques for underwater sensor networks: Theory and Design

Voltage boosting amplifier techniques for underwater sensor networks: Theory and Design

Due to the COVID-19 crisis measures the PhD defence of Amir Saifullah will take place (partly) online in the presence of an invited audience.

The PhD defence can be followed by a live stream.

Amir Saifullah is a PhD student in the research group Integrated Circuit Desgin (ICD). His supervisor is prof.dr.ir. B. Nauta from the Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS).

The innovations in the technology have changed the way we communicate today. While radio based wireless communication has entered a mature phase of commercialization, underwater communication technology is still lagging behind. The most widely used type of communication for underwater is acoustic communication. This is due to the fact that acoustic communication allows long range underwater communication as compared to optical and radio based wireless communication. However issues with slow acoustic propagation, limited available bandwidth, variations in channel propagation and power efficiency makes the development of reliable and energy efficient Underwater Sensor Networks (USNs) a major challenge.

However the development of reliable and low cost USNs has a great potential of revolutionizing many areas of underwater monitoring, sensing, navigation, detection and many more. The progress in USNs involves many key areas including signal processing, underwater channel  modeling, transducer design, energy harvesting and  efficient amplifier design, to name a few. In this thesis we focus on the techniques for an energy-efficient amplifier design, in particular the associated challenges in driving piezoelectric loads with limited supply voltages.

Therefore to gain insight into the design aspects of the amplifier, different existing amplifier topologies suitable for driving piezoelectric transducers are reviewed with focus on wide bandwidth, low distortion and supply boosting. To improve power efficiency a voltage boosting amplifier that combines signal generation and supply boosting can be a good choice for driving piezoelectric transducers.

In this thesis a new modeling technique is presented which is simple and gives accurate results for both capacitive and resistive loads. Furthermore, the useful expressions for DC gain and pole locations of a boost converter operating in Continuous-Conduction Mode (CCM) with peak current mode control are derived and compare well to simulations and measurements.

Finally the design of a high-voltage amplifier for a piezoelectric transducer is presented, which incorporates boosting and signal generation within a single boost converter stage improving the total efficiency of the system. The proposed architecture combines hysteretic ripple current-mode control with an adaptive soft switching technique to achieve improved power efficiency over the full output power range. This is achieved by dynamically controlling the inductor current ripple to keep the converter running in soft switching.