Design and Performance of the BCM1F Front End ASIC for the Beam Condition Monitoring System at the CMS Experiment

We present the design and the test results of the BCM1F front end ASIC designed for readout of diamond sensors used in the Beam Condition Monitoring system at the Compact Muon Solenoid (CMS) experiment built in the European Organization for Nuclear Research (CERN) in Geneva. The design comprises a fast transimpedance preamplifier with active feedback, a shaper stage and high-performance differential output buffer. The front end amplifier shows good linearity for input charges below 7 fC, signal gain of about 50 mV/fC, equivalent noise charge (ENC) around 400 e
^-
for 2 pF and less than 700 e
^-
for 5 pF input capacitance. The measured peaking time (T
_p
) is in the range from 6.6 to 9.4 ns depending on the applied bias conditions and the input capacitance. The full-width-at-half-maximum (FWHM) of the response is kept below 10 ns, which allows for efficient beam halo detection. The return time after the detector signal overdrive is maintained below 25 ns. These two latter parameters make the presented circuit compatible with high data rate applications.