Charge Amplifier and Analog Memory for Silicon Drift Detectors in Alice

According to our simulations [1], a preamplifier-shaper has been designed. It has 8 channels. Each channel consists of a charge preamplifier and a CR-RC shaper to limit noise. Thermal and shot noise has been simulated as 300 e-. Since the foreseen leakage current is not more than 10 nA, the preamplifier has a sensitivity of 155 mV/MIP, in order to achieve the assigned 7 Mip range. The shaper has a gain of 1 V/V and a driving capability of 7 pF as required by the 256-cell Analog Memory. A 16 channels 256 cells analog memory has been realised as a switched capacitor array. It works as an analog delay line. The read frequency is 1 MHz driving 15 pF output load and the write frequency is 40 MHz. This device has to be tested. A previous prototype (64 cells 4 channels) working at the same write and read frequency showed during tests the expected performances. Dynamic Range 3.5 V Dc gain 0.9988.