This paper presents and evaluates different power supply concepts for powering wireless sensor nodes directly from 230VAC mains. The main focus is to find a suitable concept in terms of cost- and power efficiency, which allows for high integration density. The most promising architectures are a capacitive power supply concept and a buck-boost converter concept with an advanced phase-dependent control circuit. Innovative extensions to common solutions are presented and discussed for an output power range of up to 100mW with special respect to light load efficiency.