  This paper reports on the spatial and temporal resolutions of an RSD 450
microns pitch pixels array measured at the DESY test beam facility. RSDs,
Resistive Silicon Detectors, also known as AC-LGAD, achieve excellent position
and temporal resolution by exploiting charge sharing among neighboring
electrodes. The RSD matrix used in this study is part of the second FBK RSD
production, RSD2, and it is composed of 450 microns pitch pixel with
cross-shaped electrodes. A 7-pixel matrix was read out by the FAST2 ASIC, a
16-channel amplifier fully custom ASIC developed by INFN Torino using the 110
nm CMOS technology. The total area covered by the matrix is about 1.5 mm$^2$.
The position resolution reached in this test is 15 microns, about 4\% of the
pitch. The temporal resolution achieved in this work is 60 ps, dominated by the
FAST2 resolution. The work also demonstrates that RSD sensors with cross-shaped
electrodes achieve 100% fill factor and homogenous resolutions over the whole
matrix surface, making them a suitable choice for 4D tracking applications.
