Lawrence Berkeley National Laboratory

We present architecture, critical design issues and performance measurements of PETRIC, a 64-channel mixed signal front-end integrated circuit (IC) for reading out a photodiode (PD) array coupled with LSO scintillator crystals for a medical imaging application (PET). Each channel consists of a low noise charge sensitive pre-amplifier (CSA), an RC-CR pulse shaper and a winner-take-all (WTA) multiplexer that selects the channel with the largest input signal. Triggered by an external timing signal, a switch opens and a capacitor stores the peak voltage of the winner channel. The shaper rise and fall times are adjustable by means of external current inputs over a continuous range of 0.7 (mu)s to 9 (mu)s. Power consumption is 5.4 mW per channel, measured Equivalent Noise Charge (ENC) at 1 (mu)s peaking time. Zero leakage current is 33 rms electrons plus 7.3 rms electrons per pF of input capacitance. Design is fabricated in 0.5 (mu)m 3.3V CMOS technology.