  The Wide Field Imager (WFI) is one of the two scientific instruments proposed
for the Athena+ X-ray observatory. It will provide imaging in the 0.1-15 keV
band over a wide field, simultaneously with spectrally and time-resolved photon
counting. The instrument is designed to make optimal use of the grasp
(collecting area times solid angle product) provided by the optical design of
the Athena+ mirror system (Willingale et al. 2013), by combining a sensitive
approx. 40' diameter field of view (baseline; 50' goal) DEPFET detector with a
pixel size properly sampling the angular resolution of 5 arc sec on-axis (half
energy width).This synthesis makes the WFI a very powerful survey instrument,
significantly surpassing currently existing capabilities (Nandra et al. 2013;
Aird et al. 2013). In addition, the WFI will provide unprecedented simultaneous
high-time resolution and high count rate capabilities for the observation of
bright sources with low pile-up and high efficiency. In this paper, we
summarize the instrument design, the status of the technology development, and
the baseline performance.
