A 16-CHANNEL CHARGE SENSITIVE AMPLIFIER IC FOR A PIN PHOTODIODE-ARRAY BASED PET DETECTOR MODULE

A 16-channel integrated circuit charge sensitive preamplifier has been developed for a PET detector module that uses an 8x8 array of PIN photodiodes to identify the crystal of interaction. The amplifier, which is made using 1.2 mum CMOS technology, produces an output of 100 mV per 1000 e- input, and its noise performance is optimized for 10 pF detector capacitance. The rise time, fall time, bias current through the first FET, and detector current compensation are each controlled by a dc current applied to the 2 mm square chip. The Johnson noise (e- fwhm at 1 mus peaking time) is 173 + 13C, where C is the input capacitance in pF, and the shot noise (e- fwhm) is 16.4 square-root IT, where I is the detector dark current in pA and T is the amplifier shaping time in mus. With this amplifier, the target noise of 300 e- fwhm can nearly be met with 300 mum depletion thickness photodiodes (3 pF, 200 pA per 3x3 mm element).