PETRIC - A positron emission tomography readout integrated circuit

We present the architecture, critical design issues, and performance measurements of PETRIC, a 64-channel mixed signal front-end integrated circuit for reading out a photodiode array coupled with Lu(2)SiOr(5) [Ce] scintillator crystals for a medical imaging application: positron emission topography. Each channel consists of a low-noise charge-sensitive preamplifter, an RC-CR pulse shaper and a winner-take-all 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 peaking time is adjustable by means of external current inputs over a continuous range of 0.7 mus to 9 mus. Power consumption is 5.4 mW per channel, measured equivalent noise charge at 1-mus 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-mum 3.3-V complementary metal-oxide semiconductor technology.