Noise Performance of Readout Electronics for Photodetector

A 16 channel Integrated circuit charge sensitive preamplifier (CSA) has been developed for an X-ray detector module that uses a 16 linear arrays of photodetector. The photodiode is made of 280 um thickness, 30 MOmega shunt resistivity, the measured junction capacitance 200 pF. The main performances of the CSA for photodetector are the following: the input equivalent noise charge is 300 e^- rms at peaking time 200 ns, the highest gain is 10 mV/fC, the peaking time is adjustable between 50 ns and 300 us by external passive components. The noise simulation yield ENC values of 50 e^- and 250 e^- for thermal and 1/f noise, respectively. The design was fabricated in standard 0.35 um CMOS technology and the circuit occupies an area of 4times4 mm² and dissipates 2 mW per channel from a 3.3 V single power supply.