The Wide Field Imager of the European X-Ray Observatory

The European X-ray Observatory (XRO) also denoted as X-ray Evolving Universe Spectroscopy (XEUS) mission is currently under assessment by the European Space Agency as a follow-up to XMM-Newton and Chandra with an intended launch date around 2015. XEUS/XRO aims to place an X-ray telescope in space with an aperture comparable to the largest ground based observatories. The large collecting area sets new frontiers for the focal plane instrumentation in terms of sensitive area, spectral and spatial resolution and readout speed. To cope with the challenging requirements of the XEUS/XRO Wide Field Imager a new type of Active Pixel Sensor based on the integrated amplifier DEPFET (DEpleted P-channel Field Effect Transistor) has been developed and characterized. This concept combines excellent energy resolution, high speed readout and low power consumption with the attractive features of readout on demand and random accessibility of pixels. A first series of prototype devices produced and characterized at the MPI semiconductor laboratory in Munich/Germany already meets most of the XEUS/XRO specifications. A second generation of devices with substantially larger formats is currently in production. Other device concepts and operation modes derived from the DEPFET principle are introduced.