Radiation hard integrated high-voltage DC-DC converters
For Electrical Engineering (ESAT) TC, Technology Campus Geel we are looking for a The ADVISE research group, located at the KU Leuven technology campus in Geel, has a strong reputation in the field of radiation-hard IC design. To support this, a highly-specialised measurement lab (Relylab) is available at the campus. Highlights are the X-ray radiation facility as well as an annealing chamber for Total Ionizing Dose (TID) testing. Apart from this, the impact of Single-Event Upsets (SEUs) on integrated circuits can be investigated using the two-photon absorption (TPA) laser facility. This results in a detailed sensitivity map of the integrated circuit and an increased understanding of the radiation effects.
When moving towards mobile applications, a strong need emerges for highly-efficient integrated power converters. A similar trend is observed in space applications, where a light weight and high power efficiency are key. Apart from the conversion of the high voltage output power of a solar panel or battery, also smaller, power converters are necessary to power different (on-chip) sub-blocks. In space applications, however, an increased robustness is needed to overcome the increased radiation levels and temperature swings. Total Ionizing Dose (TID) effects will mainly affect the performance of the analog blocks and switches. Single Event Transients (SETs), on the other hand, can result in an unstable output voltage and instabilities in the control system. Charge injections can switch-on high-voltage devices, resulting in malfunction or even breakdown of the power converter.
The purpose of this PhD is to develop a highly-efficient radiation hardened high-voltage DC-DC converter. Voltages up to 100 V will be investigated. Measures will be taken to overcome the impact of SETs as well as TID effects and to avoid the (gate-)capacitors from breakdown: injected charges as a result of heavy ion strikes are typically in the order of 1-2 pC, resulting in a 10V voltage increase on a 100 fF capacitor. To characterize the effect of radiation on (GaN) power FETs, measurements on commercially available components will be done using the X-Ray as well as the TPA laser facility in the ADVISE Relylab. The trade-offs between efficiency, robustness, stability and chip area need to be investigated to obtain an optimal solution in different use-cases. The efficiency of the developed converter as a function of the TID will be characterized up to TID levels of 200 Mrad(Si).
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