HGCROC3: the front-end readout ASIC for the CMS High Granularity Calorimeter

<!--HTML-->For the CMS HGCAL, the final version of the 72-channel front-end ASIC (HGCROC3) was submitted in December 2020. HGCROC3 includes low-noise/high-gain preamplifier/shapers, and a 10-bit 40 MHz SAR-ADC, which provides the charge measurement over the linear range of the preamplifier. In the saturation range a discriminator and TDC provide the charge information from TOT (200ns dynamic range, 50ps binning). A fast discriminator and TDC provide timing information to 25ps accuracy. The chip embeds all necessary ancillary services: bandgap circuit, PLL, threshold DACs. We present the experimental results on the latest and final version HGCROC3 received in April 2021.