Design and Performance of the FBCM23 ASIC for the CMS Luminosity Measurement

We present the design and evaluation of the FBCM23 ASIC designed for the Fast Beam Condition Monitoring (FBCM) system intended for the luminosity measurements in the upgraded CMS experiment at CERN. The ASIC is implemented in a CMOS 65 nm technology and consists of six front-end channels with a binary architecture optimized to work with $1.7\times 1.7$ mm² area and 290 or $150 \,\mu $ m thick silicon sensors. The presented ASIC will replace the existing system to comply with new, challenging specifications concerning the time resolution (1 ns rms) and noise, the latter related to the expected radiation damages of the sensors located at a radius close to 14.5 cm. The expected total ionizing dose (TID) and the fluence at the end of the experiment lifetime are 200 Mrad and $2.5\times 10^{15}~\text {n}/\text {cm}^{2}$ , 1 MeV equivalent, respectively. We present the design and a complete characterization of the ASIC, including TID irradiation, single-event upset (SEU) tests, thermal drifts, and performance of the ASIC connected to the sensor.