ANUINDRA: A wide dynamic range FEE ASIC for a silicon–tungsten electromagnetic calorimeter

A wide dynamic range (ratio of maximum detectable signal to noise floor) front end electronics (FEE) readout ASIC ANUINDRA has been developed in 0.35μm standard N-well CMOS technology for the prototype forward calorimeter (FOCAL), a silicon–tungsten (Si–W) electromagnetic (EM) calorimeter, proposed as part of the ALICE upgrade at CERN. It is a 16 channel pulse processing ASIC with a multiplexed serial output along with all the individual channel’s responses available as output pins. Each channel consists of a charge sensitive amplifier (CSA), semi-Gaussian pulse shaper, gain-stage, and Track & Hold stage. The ASIC has been designed with a linear operating range of 2.6 pC w.r.t the input charge and a measured charge gain of 1.34 mV/fC. ANUINDRA ASIC shows a noise level (ENC) of 820 e$^-$ with 0 pF of detector capacitance. A baseline recovery of better than 1% within 5μs can be attained by adjusting the pole–zero locations with the help of external voltage control. The fabricated and packaged ANUINDRA was successfully tested and characterized in the laboratory and with a high energy particle beam at the SPS beamline in CERN. The design details of ANUINDRA ASIC along with the test results are presented herewith in this paper.