Fully integrated readout channel with amplitude and time measurement for AMS experiment on ISSA

AMS (Anti-Matter Spectrometer) is a high energy physics experiment to be installed on the International Space Station Alpha (ISSA). The goal of this experiment is to search for antimatter in space. In one section of this experiment an array of sensors is used to detect incoming particle trajectory. Each of these sensors, when it is hit by a particle, gives a charge pulse Qin, which is the input signal for one readout channel. The purpose of each readout channel is to collect the signal charge and to produce two voltage levels: one must be proportional to the amount of charge Q while the other is required to be proportional to the delay, with respect to the hit time, of a fixed instant To, common to all the channels in the system. The maximum charge amount which can be injected into the channel is 6 pC; for the amplitude measurement an 8 bit resolution is required. On the other hand, for the time measurement a 3 ns precision is required, with a 6 bit accuracy output signal. Due to the large number of these readout channels and to the reduced energy available in the space station, a low power consumption for each channel is allowed (<5.5 mW). The whole readout system has been designed in HF3CMOS, a BiCMOS technology with 1.2 μm minimum CMOS channel length. The system operates with a single 4 V supply consuming 4.8 mW