  We are developing transition-edge sensor (TES)-based microcalorimeters for
the X-ray Integral Field Unit (XIFU) of the future European X-Ray Observatory
Athena. The microcalorimeters are based on TiAu TESs coupled to 250{\mu}m
squared, AuBi absorbers. We designed and fabricated devices with different
contact geometries between the absorber and the TES to optimise the detector
performance and with different wiring topology to mitigate the self-magnetic
field. The design is tailored to optimise the performance under Frequency
Domain Multiplexing. In this paper we review the main design feature of the
pixels array and we report on the performance of the 18 channels, 2-5MHz
frequency domain multiplexer that will be used to characterised the detector
array.
