  We designed, produced, and tested RSD (Resistive AC-Coupled Silicon
Detectors) devices, an evolution of the standard LGAD (Low-Gain Avalanche
Diode) technology where a resistive n-type implant and a coupling dielectric
layer have been implemented. The first feature works as a resistive sheet,
freezing the multiplied charges, while the second one acts as a capacitive
coupling for readout pads. We succeeded in the challenging goal of obtaining
very fine pitch (50, 100, and 200 um) while maintaining the signal waveforms
suitable for high timing and 4D-tracking performances, as in the standard
LGAD-based devices.
