  The Medipix4 chip is the latest member in the Medipix/Timepix family of
hybrid pixel detector chips aimed at high-rate spectroscopic X-ray imaging
using high-Z materials. It can be tiled on all 4 sides making it ideal for
constructing large-area detectors with minimal dead area. The chip is designed
to read out a sensor of 320 x 320 pixels with dimensions of 75 {\mu}m x 75
{\mu}m or 160 x 160 pixels with dimensions of 150 {\mu}m x 150 {\mu}m. The
readout architecture features energy binning of the single photons, which
includes charge sharing correction for hits with energy spread over adjacent
pixels. This paper presents the specifications, architecture, and circuit
implementation of the chip, along with the first electrical measurements.

Instrumentation and Detectors