Vibration powered electrical generators produce a raw AC electrical output that often needs to be converted into DC for use by the load systems. There are many possible ways to achieve this conversion (rectification) however the specific application of vibration energy harvesting requires a solution that is a delicate balance between efficiency, converter quiescent loss and impact upon the resonant generator operation. In this paper we investigate how vibration powered generators interact with typical rectification schemes and assess the overall system performance, comparing it to the theoretical maximum power that could be generated. Further to this we present practical circuits that address the inherent problems of passive rectification techniques including a unity power factor power converter, realised at ultra low powers, suitable for energy harvesting applications. Numerical models are validated with measured results.