Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here.

No abstract

Using an original micro-dataset from France, we investigate nominal wage stickiness. Nominal wage changes are found to occur at a quarterly frequency of around 38 percent over our sample period, and to be to a large extent staggered across establishments, and very synchronized within establishments. We carry out an econometric analysis of wage changes based on a two-threshold sample selection model. Our results are that the timing of wage adjustments is time-dependent as opposed to state-dependent, there is evidence of predetermination in wage changes, and both backward and forward-looking behavior is relevant in wage setting. (JEL E24, E52, J31)

No abstract

No abstract

No abstract

This paper examines an inductive power transfer (IPT) system with a rotary transformer as an alternative solution to slip ring systems for a contactless energy transfer to rotating equipment. A prototype system is set up, consisting of a rotating ball bearing shaft and an exemplary sensor circuit mounted on the shaft. Three possible transformer configurations are analyzed theoretically and experimentally regarding the self-inductance, the coupling factor and the losses in the litz wire. To utilize the intrinsic stray inductances of the rotary transformer, a series compensated resonant converter is implemented for the prototype system

Modeling of parasitic semiconductor device capacitances has always been a difficult task due to their nonlinearities. In this paper, we present a novel charge based model which provides simplification and ease of the modeling process. Further-more, convergence errors are reduced and the simulation speed is enhanced by up to a factor of two compared to state of the art models. This is especially important for novel SiC and GaN devices which allow for increased switching frequencies and thus a higher number of switching cycles per time period. Moreover, the presented modeling approach can easily be automated which is a significant advantage compared to state of the art models consisting of arbitrary mathematical equations