TOT02, a time-over-threshold based readout chip in 180 nm CMOS process for long silicon strip detectors

We report on the design and measurements of multichannel ASIC named TOT02, dedicated for the readout of silicon long strip detectors of the Silicon Tracking System (STS) in the CBM experiment at FAIR, GSI. This Integrated Circuit adapts the time-over-threshold (ToT) method for detectors with large capacitance (30pF). The prototype chip has 16 channels comprising of a charge sensitive amplifier with a constant current discharge and a discriminator with 6-bit trimming DAC and it is supplied with digital back-end. The paper presents details of architecture, ENC estimation methodology for ToT systems and test setup together with measurement and simulation results.